Discussion:
Faulty consumer unit
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JNugent
2024-05-13 13:52:55 UTC
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When we moved into this house just over thirty years ago, in addition to
all the usual (new kitchen, double-glazing, new bathroom), we had a new
consumer unit fitted, located where the previous fusebox had been - out
in the garage.

The unit seems to be standard fare, with separate trips for ring main,
upstairs lighting, downstairs lighting and a 30 amp circuit for an
electric shower.

Some years ago, we started to get trouble from the Triton shower. When
set to its higher temperature, it would sometimes trip the consumer unit
off completely. Apart from the general inconvenience of that, in those
days, the garage was only accessible from outdoors and if home alone,
resetting the unit would involve wrapping a wet body in towels and going
out into the back garden and into the garage's back door. Annoying or what?

On the lower temperature setting, the problem did not occur. Until
recently, though with the difference that only the shower trip cuts out
(and we now have a door from the house direct into the garage!).

This is the second or third Triton shower unit we've had in that 30+
years with the same results from the last two at least. For that reason,
my suspicion is that this is a fault at the consumer unit, and with the
shower trip in particular.

Yes, I am aware that I should have done something about it a few years
ago, but I certainly want to do it now. From experience, does this sound
like an issue where the remedy is a whole new consumer unit, please?

I hope it is...
Jack Harry Teesdale
2024-05-13 14:03:44 UTC
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Post by JNugent
When we moved into this house just over thirty years ago, in addition to
all the usual (new kitchen, double-glazing, new bathroom), we had a new
consumer unit fitted, located where the previous fusebox had been - out
in the garage.
The unit seems to be standard fare, with separate trips for ring main,
upstairs lighting, downstairs lighting and a 30 amp circuit for an
electric shower.
Some years ago, we started to get trouble from the Triton shower. When
set to its higher temperature, it would sometimes trip the consumer unit
off completely. Apart from the general inconvenience of that, in those
days, the garage was only accessible from outdoors and if home alone,
resetting the unit would involve wrapping a wet body in towels and going
out into the back garden and into the garage's back door. Annoying or what?
On the lower temperature setting, the problem did not occur. Until
recently, though with the difference that only the shower trip cuts out
(and we now have a door from the house direct into the garage!).
This is the second or third Triton shower unit we've had in that 30+
years with the same results from the last two at least. For that reason,
my suspicion is that this is a fault at the consumer unit, and with the
shower trip in particular.
Yes, I am aware that I should have done something about it a few years
ago, but I certainly want to do it now. From experience, does this sound
like an issue where the remedy is a whole new consumer unit, please?
I hope it is...
A new consumer unit with RCBO's would be one answer. it would not
necessarily prevent nuisance tripping caused by faulty appliances
(including electric showers) but would be safer in that event.
JNugent
2024-05-13 14:27:46 UTC
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Post by Jack Harry Teesdale
Post by JNugent
When we moved into this house just over thirty years ago, in addition
to all the usual (new kitchen, double-glazing, new bathroom), we had a
new consumer unit fitted, located where the previous fusebox had been
- out in the garage.
The unit seems to be standard fare, with separate trips for ring main,
upstairs lighting, downstairs lighting and a 30 amp circuit for an
electric shower.
Some years ago, we started to get trouble from the Triton shower. When
set to its higher temperature, it would sometimes trip the consumer
unit off completely. Apart from the general inconvenience of that, in
those days, the garage was only accessible from outdoors and if home
alone, resetting the unit would involve wrapping a wet body in towels
and going out into the back garden and into the garage's back door.
Annoying or what?
On the lower temperature setting, the problem did not occur. Until
recently, though with the difference that only the shower trip cuts
out (and we now have a door from the house direct into the garage!).
This is the second or third Triton shower unit we've had in that 30+
years with the same results from the last two at least. For that
reason, my suspicion is that this is a fault at the consumer unit, and
with the shower trip in particular.
Yes, I am aware that I should have done something about it a few years
ago, but I certainly want to do it now. From experience, does this
sound like an issue where the remedy is a whole new consumer unit,
please?
I hope it is...
A new consumer unit with RCBO's would be one answer. it would not
necessarily prevent nuisance tripping caused by faulty appliances
(including electric showers) but would be safer in that event.
Thanks for that.

I have no reason to suspect that the shower is faulty. We have
occasionally had trouble with the ring main trip when toasters or
kettles have become U/S. A friend observed that it's always a kettle or
a toaster.
Tricky Dicky
2024-05-13 14:17:42 UTC
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Post by JNugent
When we moved into this house just over thirty years ago, in addition to
all the usual (new kitchen, double-glazing, new bathroom), we had a new
consumer unit fitted, located where the previous fusebox had been - out
in the garage.
The unit seems to be standard fare, with separate trips for ring main,
upstairs lighting, downstairs lighting and a 30 amp circuit for an
electric shower.
Some years ago, we started to get trouble from the Triton shower. When
set to its higher temperature, it would sometimes trip the consumer unit
off completely. Apart from the general inconvenience of that, in those
days, the garage was only accessible from outdoors and if home alone,
resetting the unit would involve wrapping a wet body in towels and going
out into the back garden and into the garage's back door. Annoying or what?
On the lower temperature setting, the problem did not occur. Until
recently, though with the difference that only the shower trip cuts out
(and we now have a door from the house direct into the garage!).
This is the second or third Triton shower unit we've had in that 30+
years with the same results from the last two at least. For that reason,
my suspicion is that this is a fault at the consumer unit, and with the
shower trip in particular.
Yes, I am aware that I should have done something about it a few years
ago, but I certainly want to do it now. From experience, does this sound
like an issue where the remedy is a whole new consumer unit, please?
I hope it is...
Is the cable to the shower correct in the days of 7Kw showers 6mm2 was the
usual connection. More modern showers of 10 - 11Kw really need 10mm2. This
aspect is often overlooked by DIYers when replacing electric showers. Also
is the MCB up to providing the current drawn something in the/region of
40-45A may be more appropriate.
JNugent
2024-05-13 14:24:49 UTC
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Post by Tricky Dicky
Post by JNugent
When we moved into this house just over thirty years ago, in addition to
all the usual (new kitchen, double-glazing, new bathroom), we had a new
consumer unit fitted, located where the previous fusebox had been - out
in the garage.
The unit seems to be standard fare, with separate trips for ring main,
upstairs lighting, downstairs lighting and a 30 amp circuit for an
electric shower.
Some years ago, we started to get trouble from the Triton shower. When
set to its higher temperature, it would sometimes trip the consumer unit
off completely. Apart from the general inconvenience of that, in those
days, the garage was only accessible from outdoors and if home alone,
resetting the unit would involve wrapping a wet body in towels and going
out into the back garden and into the garage's back door. Annoying or what?
On the lower temperature setting, the problem did not occur. Until
recently, though with the difference that only the shower trip cuts out
(and we now have a door from the house direct into the garage!).
This is the second or third Triton shower unit we've had in that 30+
years with the same results from the last two at least. For that reason,
my suspicion is that this is a fault at the consumer unit, and with the
shower trip in particular.
Yes, I am aware that I should have done something about it a few years
ago, but I certainly want to do it now. From experience, does this sound
like an issue where the remedy is a whole new consumer unit, please?
I hope it is...
Is the cable to the shower correct in the days of 7Kw showers 6mm2 was the
usual connection. More modern showers of 10 - 11Kw really need 10mm2. This
aspect is often overlooked by DIYers when replacing electric showers. Also
is the MCB up to providing the current drawn something in the/region of
40-45A may be more appropriate.
The wiring was all done professionally.

I served an apprenticeship in electrical engineering, but would always
stop at replacing sockets, switches, etc at home. Certainly no digging
out the plaster and re-wiring!

But still, I'll have that checked out too. Thanks.
Theo
2024-05-13 14:39:36 UTC
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Post by JNugent
Post by Tricky Dicky
Is the cable to the shower correct in the days of 7Kw showers 6mm2 was the
usual connection. More modern showers of 10 - 11Kw really need 10mm2. This
aspect is often overlooked by DIYers when replacing electric showers. Also
is the MCB up to providing the current drawn something in the/region of
40-45A may be more appropriate.
The wiring was all done professionally.
I served an apprenticeship in electrical engineering, but would always
stop at replacing sockets, switches, etc at home. Certainly no digging
out the plaster and re-wiring!
But still, I'll have that checked out too. Thanks.
If you can tell us:
1. The model of the shower and its kW rating
2. The rating of the MCB and its curve
(letter and number will be printed on the front like B40, C32)
3. The size of the cable (4/6/10mm2)

Then we can make guesses as to how marginal things are.

Most showers have four heat positions: 'off', 'cold', 'I' and 'II'
which correspond to inlet valve closed ('off') and open with 0, 1 and 2
heating coils in circuit. The knob for fine temperature control actually
controls the water flow rate.

When in 'I' it's only taking a fraction of the current that it does in 'II'
(not necessarily half, I think it might be more like 60% in some showers,
the coil resistance may be stated somewhere) so unsurprising it doesn't trip
in 'I'.

MCBs have trip curves which aren't perfectly specified - they're supposed to
trip at multiples of the fault current within a specified time. If you take
them a small amount over the rated current they may take hours to trip, but
that amount could change as they age.

The length of the shower could also affect things - eg if you take longer
than you once did, you'd only notice now. Maybe you had a 5 minute shower
before so you didn't notice it tripping after 10 mins.

It's no guarantee that just swapping the MCB will make it better (could make
it worse), but we can tell you if it's marginal and what upgrades might be
needed to fix it.

Theo
(whose 10.8kW shower failed EICR because it was on 6mm2 cable, now
thankfully gone)
Theo
2024-05-13 14:50:56 UTC
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Post by Theo
Post by JNugent
Post by Tricky Dicky
Is the cable to the shower correct in the days of 7Kw showers 6mm2 was the
usual connection. More modern showers of 10 - 11Kw really need 10mm2. This
aspect is often overlooked by DIYers when replacing electric showers. Also
is the MCB up to providing the current drawn something in the/region of
40-45A may be more appropriate.
The wiring was all done professionally.
I served an apprenticeship in electrical engineering, but would always
stop at replacing sockets, switches, etc at home. Certainly no digging
out the plaster and re-wiring!
But still, I'll have that checked out too. Thanks.
1. The model of the shower and its kW rating
2. The rating of the MCB and its curve
(letter and number will be printed on the front like B40, C32)
3. The size of the cable (4/6/10mm2)
Forgot to add:

4. Where the cable goes and roughly how long it is.

Specifically I'm interested in which 'reference methods' apply:
https://www.procertssoftware.com/blog/bs-7671-reference-methods/
If more than one, how long of each.

(these are used to calculate the thermal overload parameters for the cable.
Not strictly relevant for the trip, but will indicate whether the cable is
correctly specified for the shower you have)

Theo
Jeff Layman
2024-05-13 14:54:15 UTC
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Post by JNugent
Post by Tricky Dicky
Post by JNugent
When we moved into this house just over thirty years ago, in addition to
all the usual (new kitchen, double-glazing, new bathroom), we had a new
consumer unit fitted, located where the previous fusebox had been - out
in the garage.
The unit seems to be standard fare, with separate trips for ring main,
upstairs lighting, downstairs lighting and a 30 amp circuit for an
electric shower.
Some years ago, we started to get trouble from the Triton shower. When
set to its higher temperature, it would sometimes trip the consumer unit
off completely. Apart from the general inconvenience of that, in those
days, the garage was only accessible from outdoors and if home alone,
resetting the unit would involve wrapping a wet body in towels and going
out into the back garden and into the garage's back door. Annoying or what?
On the lower temperature setting, the problem did not occur. Until
recently, though with the difference that only the shower trip cuts out
(and we now have a door from the house direct into the garage!).
This is the second or third Triton shower unit we've had in that 30+
years with the same results from the last two at least. For that reason,
my suspicion is that this is a fault at the consumer unit, and with the
shower trip in particular.
Yes, I am aware that I should have done something about it a few years
ago, but I certainly want to do it now. From experience, does this sound
like an issue where the remedy is a whole new consumer unit, please?
I hope it is...
Is the cable to the shower correct in the days of 7Kw showers 6mm2 was the
usual connection. More modern showers of 10 - 11Kw really need 10mm2. This
aspect is often overlooked by DIYers when replacing electric showers. Also
is the MCB up to providing the current drawn something in the/region of
40-45A may be more appropriate.
The wiring was all done professionally.
I served an apprenticeship in electrical engineering, but would always
stop at replacing sockets, switches, etc at home. Certainly no digging
out the plaster and re-wiring!
But still, I'll have that checked out too. Thanks.
I can surmise a strange situation which /might/ result in what occurs,
and involves neither a fault in the shower nor the CU. I assume that
what you were originally referring to is the RCD tripping rather than
the MCB (all power lost), but the MCB only is tripping now (only power
to the shower is lost).

If TD is right, and the cabling is running near to its limit, consider a
mouse or rat chewing through the insulation of both live and earth.
Running at full power the cabling got hot, and expanded and/or sagged
enough to touch the earth, so tripping the RCD. However, if not running
at full power for several minutes the cabling never got that hot and did
not touch the earth, so no tripping occurred. Perhaps further insulation
has been removed in a slightly different place and live and neutral are
now touching rather than earth, so tripping the MCB rather than the RCD.

Crazy speculation I admit, but we've all heard of Sod's Law...
--
Jeff
Chris Green
2024-05-14 10:36:33 UTC
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Post by JNugent
Post by Tricky Dicky
Post by JNugent
When we moved into this house just over thirty years ago, in addition to
all the usual (new kitchen, double-glazing, new bathroom), we had a new
consumer unit fitted, located where the previous fusebox had been - out
in the garage.
The unit seems to be standard fare, with separate trips for ring main,
upstairs lighting, downstairs lighting and a 30 amp circuit for an
electric shower.
Some years ago, we started to get trouble from the Triton shower. When
set to its higher temperature, it would sometimes trip the consumer unit
off completely. Apart from the general inconvenience of that, in those
days, the garage was only accessible from outdoors and if home alone,
resetting the unit would involve wrapping a wet body in towels and going
out into the back garden and into the garage's back door. Annoying or what?
On the lower temperature setting, the problem did not occur. Until
recently, though with the difference that only the shower trip cuts out
(and we now have a door from the house direct into the garage!).
This is the second or third Triton shower unit we've had in that 30+
years with the same results from the last two at least. For that reason,
my suspicion is that this is a fault at the consumer unit, and with the
shower trip in particular.
Yes, I am aware that I should have done something about it a few years
ago, but I certainly want to do it now. From experience, does this sound
like an issue where the remedy is a whole new consumer unit, please?
I hope it is...
Is the cable to the shower correct in the days of 7Kw showers 6mm2 was the
usual connection. More modern showers of 10 - 11Kw really need 10mm2. This
aspect is often overlooked by DIYers when replacing electric showers. Also
is the MCB up to providing the current drawn something in the/region of
40-45A may be more appropriate.
The wiring was all done professionally.
I served an apprenticeship in electrical engineering, but would always
stop at replacing sockets, switches, etc at home. Certainly no digging
out the plaster and re-wiring!
But still, I'll have that checked out too. Thanks.
This does sound to me one of the most likely reasons for the fault. A
30 amp breaker is only *just* big enough to run a 7kW shower, even
then only if the voltage is really 240 volts. (30 * 240 / 1000 is
7.2kW). If the shower is *any* more than 7kW then it *should* trip
the MCB as it will be taking more than 30 amps. It will only trip
after quite a while though as MCBs don't trip instantly on small
overloads.
--
Chris Green
·
Alan Lee
2024-05-14 16:05:43 UTC
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If the shower is*any* more than 7kW then it*should* trip
the MCB as it will be taking more than 30 amps. It will only trip
after quite a while though as MCBs don't trip instantly on small
overloads.
No, it will run for a long time on a 10kw load, ~43 amps. Contrary to
popular belief, a 32 amp breaker does not trip at 33 amps, at 10kW/43
amps, it will run for roughly 10000 seconds+ (nearly 3 hours) , it will
be down to the thermal element inside the circuit breaker as to when it
trips, Manufacturers data will show that.
So, for a typical shower user, the overload of a 10kW shower on a 32 amp
circuit will never be noticed.
The OP said it took out the whole CU, which means it tripped the upfront
RCD. That is not an overload / circuit breaker issue, it is an earth
fault issue, which could be live to earth or neutral to earth, either of
which will trip the RCD.
Anyway, a 30/32A CB isnt going to trip with a 10kW shower.
RJH
2024-05-14 17:07:35 UTC
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Post by Alan Lee
If the shower is*any* more than 7kW then it*should* trip
the MCB as it will be taking more than 30 amps. It will only trip
after quite a while though as MCBs don't trip instantly on small
overloads.
No, it will run for a long time on a 10kw load, ~43 amps. Contrary to
popular belief, a 32 amp breaker does not trip at 33 amps, at 10kW/43
amps, it will run for roughly 10000 seconds+ (nearly 3 hours) , it will
be down to the thermal element inside the circuit breaker as to when it
trips, Manufacturers data will show that.
So, for a typical shower user, the overload of a 10kW shower on a 32 amp
circuit will never be noticed.
The OP said it took out the whole CU, which means it tripped the upfront
RCD. That is not an overload / circuit breaker issue, it is an earth
fault issue, which could be live to earth or neutral to earth, either of
which will trip the RCD.
Anyway, a 30/32A CB isnt going to trip with a 10kW shower.
I took '30 amp circuit' to mean 32A cable - I'd imagine the cable gets quite
toasty in places after a 10 minute shower.

Whether that'd trip anything, not sure - you seem to suggest not. Which
doesn't help with the cause of the fault, but does suggest the cable at least
needs sorting out. If indeed it is 6mm - perhaps the OP could confirm . . .
--
Cheers, Rob, Sheffield UK
Alan Lee
2024-05-15 07:04:06 UTC
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Post by RJH
Post by Alan Lee
Anyway, a 30/32A CB isnt going to trip with a 10kW shower.
I took '30 amp circuit' to mean 32A cable - I'd imagine the cable gets quite
toasty in places after a 10 minute shower.
Not really. The cable is rated to run at 70 deg C at full load. This
will take quite a long time to reach 70 deg, probably one hour+, as the
cables are generally rated higher than BS7671 allows.
In general, there is a 20% over-spec allowance built in, add in that a
6mm T+E cable, buried/plastered in a wall has a current carrying
capacity of 47 amps, then it will never get to full temperature with a
43 amp load, never mind going over 70 deg C.
If it was a 4mm cable (very very rare, would have to be from the early
70's) then that will have a current carrying capacity of 37 amps, which,
potentially, will go above 70 deg. C if used for a long time at 43 amps,
but for 10 minutes use, it will never get near to 70 deg C. It's a bad
design,that would not be passed in an Inspection, but in the real world
will work fine, with no imminent danger.
Post by RJH
Whether that'd trip anything, not sure - you seem to suggest not. Which
doesn't help with the cause of the fault, but does suggest the cable at least
needs sorting out. If indeed it is 6mm - perhaps the OP could confirm . . .
No, if in the plaster of the walls, or surface mounted, 6mm T+E will
carry 47 amps forever. If it is in any insulation, then the current
carrying capacity is reduced, as its thermal emitting properties are
reduced, so it can get hotter more quickly.
As for it tripping, if it was the RCD that tripped, it would not be an
overload problem, it will be an earth fault.
RJH
2024-05-15 10:20:55 UTC
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Post by Alan Lee
Post by RJH
Post by Alan Lee
Anyway, a 30/32A CB isnt going to trip with a 10kW shower.
I took '30 amp circuit' to mean 32A cable - I'd imagine the cable gets quite
toasty in places after a 10 minute shower.
Not really. The cable is rated to run at 70 deg C at full load. This
will take quite a long time to reach 70 deg, probably one hour+, as the
cables are generally rated higher than BS7671 allows.
In general, there is a 20% over-spec allowance built in, add in that a
6mm T+E cable, buried/plastered in a wall has a current carrying
capacity of 47 amps, then it will never get to full temperature with a
43 amp load, never mind going over 70 deg C.
If it was a 4mm cable (very very rare, would have to be from the early
70's) then that will have a current carrying capacity of 37 amps, which,
potentially, will go above 70 deg. C if used for a long time at 43 amps,
but for 10 minutes use, it will never get near to 70 deg C. It's a bad
design,that would not be passed in an Inspection, but in the real world
will work fine, with no imminent danger.
OK, thanks. Does make the 10mm cable an electrician asked me to install seem
like overkill for a 10kW shower then. Wonder why the shower manufacturer
recommended 10mm. Anyway. There, as they say, it is :-)
Post by Alan Lee
Post by RJH
Whether that'd trip anything, not sure - you seem to suggest not. Which
doesn't help with the cause of the fault, but does suggest the cable at least
needs sorting out. If indeed it is 6mm - perhaps the OP could confirm . . .
No, if in the plaster of the walls, or surface mounted, 6mm T+E will
carry 47 amps forever. If it is in any insulation, then the current
carrying capacity is reduced, as its thermal emitting properties are
reduced, so it can get hotter more quickly.
As for it tripping, if it was the RCD that tripped, it would not be an
overload problem, it will be an earth fault.
As I say - 10mm is only what the electrician recommended to me, although this
was partly for future proofing, as well as required for a 9.5kW shower.

As it happens, for other reasons, I'm not using him. Or installing an electric
shower - another story . . .
--
Cheers, Rob, Sheffield UK
The Natural Philosopher
2024-05-13 14:47:23 UTC
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Post by JNugent
This is the second or third Triton shower unit we've had in that 30+
years with the same results from the last two at least. For that reason,
my suspicion is that this is a fault at the consumer unit, and with the
shower trip in particular.
Yes, I am aware that I should have done something about it a few years
ago, but I certainly want to do it now. From experience, does this sound
like an issue where the remedy is a whole new consumer unit, please?
No. It sounds much more like you have an issue with the *wiring* on that
circuit.

Possibly an earth neutral leak if its happening to trip the earth
leakage, or if its tripping the overcurrent MCB, earth neutral.

I assume this is a spur, not on a ring main? In either case get a megger
on to the circuit when its isolated from the CU AND all loads

And have a good look at the wiring wherever you can to ensure that its
not your RCD (Rodent current detector ) refrying a rat...

Loading Image...
--
The biggest threat to humanity comes from socialism, which has utterly
diverted our attention away from what really matters to our existential
survival, to indulging in navel gazing and faux moral investigations
into what the world ought to be, whilst we fail utterly to deal with
what it actually is.
JNugent
2024-05-13 15:23:07 UTC
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Post by The Natural Philosopher
Post by JNugent
This is the second or third Triton shower unit we've had in that 30+
years with the same results from the last two at least. For that reason,
my suspicion is that this is a fault at the consumer unit, and with the
shower trip in particular.
Yes, I am aware that I should have done something about it a few years
ago, but I certainly want to do it now. From experience, does this sound
like an issue where the remedy is a whole new consumer unit, please?
No. It sounds much more like you have an issue with the *wiring* on that
circuit.
Possibly an earth neutral leak if its happening to trip the earth
leakage, or if its tripping the overcurrent MCB, earth neutral.
I assume this is a spur, not on a ring main? In either case get a megger
on to the circuit when its isolated from the CU AND all loads
And have a good look at the wiring wherever you can to ensure that its
not your RCD (Rodent current detector ) refrying a rat...
http://vps.templar.co.uk/AGA%20trip%20fault%20find/1002.png
Thanks for all the responses.

While I can easily quote the shower model (Triton Madrid II, about
10kW), the rest of it sounds like a job for a proper professional.

Many thanks to all who have offered advice here. I am grateful.
Chris Green
2024-05-14 10:38:36 UTC
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Post by JNugent
Post by The Natural Philosopher
Post by JNugent
This is the second or third Triton shower unit we've had in that 30+
years with the same results from the last two at least. For that reason,
my suspicion is that this is a fault at the consumer unit, and with the
shower trip in particular.
Yes, I am aware that I should have done something about it a few years
ago, but I certainly want to do it now. From experience, does this sound
like an issue where the remedy is a whole new consumer unit, please?
No. It sounds much more like you have an issue with the *wiring* on that
circuit.
Possibly an earth neutral leak if its happening to trip the earth
leakage, or if its tripping the overcurrent MCB, earth neutral.
I assume this is a spur, not on a ring main? In either case get a megger
on to the circuit when its isolated from the CU AND all loads
And have a good look at the wiring wherever you can to ensure that its
not your RCD (Rodent current detector ) refrying a rat...
http://vps.templar.co.uk/AGA%20trip%20fault%20find/1002.png
Thanks for all the responses.
While I can easily quote the shower model (Triton Madrid II, about
10kW), the rest of it sounds like a job for a proper professional.
Well that's the problem! A 10kW shower needs a 45A circuit breaker
and wiring.
--
Chris Green
·
Theo
2024-05-14 11:06:27 UTC
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Post by Chris Green
Post by JNugent
Thanks for all the responses.
While I can easily quote the shower model (Triton Madrid II, about
10kW), the rest of it sounds like a job for a proper professional.
Well that's the problem! A 10kW shower needs a 45A circuit breaker
and wiring.
The OP hasn't told as what circuit breaker or wiring they have, AFAICS.
That's why I asked. Otherwise we're just guessing.

(even just telling us the number written on the MCB would be enough to work
out if it's suitable or not)

Theo
RJH
2024-05-14 13:38:07 UTC
Reply
Permalink
Post by Theo
Post by Chris Green
Post by JNugent
Thanks for all the responses.
While I can easily quote the shower model (Triton Madrid II, about
10kW), the rest of it sounds like a job for a proper professional.
Well that's the problem! A 10kW shower needs a 45A circuit breaker
and wiring.
The OP hasn't told as what circuit breaker or wiring they have, AFAICS.
That's why I asked. Otherwise we're just guessing.
(even just telling us the number written on the MCB would be enough to work
out if it's suitable or not)
Theo
OP mentioned 30A for the shower.
--
Cheers, Rob, Sheffield UK
Theo
2024-05-14 13:48:22 UTC
Reply
Permalink
Post by RJH
Post by Theo
Post by Chris Green
Post by JNugent
Thanks for all the responses.
While I can easily quote the shower model (Triton Madrid II, about
10kW), the rest of it sounds like a job for a proper professional.
Well that's the problem! A 10kW shower needs a 45A circuit breaker
and wiring.
The OP hasn't told as what circuit breaker or wiring they have, AFAICS.
That's why I asked. Otherwise we're just guessing.
(even just telling us the number written on the MCB would be enough to work
out if it's suitable or not)
Theo
OP mentioned 30A for the shower.
Oh yes, I missed that in the OP. That will be the problem then. 30A is way
too low, only enough for a 7.2kW shower.

Theo
Andrew Gabriel
2024-05-13 15:35:56 UTC
Reply
Permalink
Post by JNugent
When we moved into this house just over thirty years ago, in addition to
all the usual (new kitchen, double-glazing, new bathroom), we had a new
consumer unit fitted, located where the previous fusebox had been - out
in the garage.
The unit seems to be standard fare, with separate trips for ring main,
upstairs lighting, downstairs lighting and a 30 amp circuit for an
electric shower.
Some years ago, we started to get trouble from the Triton shower. When
set to its higher temperature, it would sometimes trip the consumer unit
off completely. Apart from the general inconvenience of that, in those
days, the garage was only accessible from outdoors and if home alone,
resetting the unit would involve wrapping a wet body in towels and going
out into the back garden and into the garage's back door. Annoying or what?
On the lower temperature setting, the problem did not occur. Until
recently, though with the difference that only the shower trip cuts out
(and we now have a door from the house direct into the garage!).
This is the second or third Triton shower unit we've had in that 30+
years with the same results from the last two at least. For that reason,
my suspicion is that this is a fault at the consumer unit, and with the
shower trip in particular.
Yes, I am aware that I should have done something about it a few years
ago, but I certainly want to do it now. From experience, does this sound
like an issue where the remedy is a whole new consumer unit, please?
With high current circuits, it's worth checking the connections
periodically, as the thermal cycling tends to cause them to go bad
faster, which causes larger thermal cycling, heading in to burnout.
Depending what form they take, and slight slackening and retightening
would do this (with circuits isolated, obviously). In commercial
premises, they are sometimes inspected with infra-red cameras to check
for hot terminals.

Heating of the MCB terminals will cause the MCB to run hotter, and hence
trip at a lower current too. Heating of an adjacent MCB can have the
same effect, as can having two adjacent MCBs running near full load.
--
Andrew
SteveW
2024-05-13 23:03:32 UTC
Reply
Permalink
Post by JNugent
When we moved into this house just over thirty years ago, in addition to
all the usual (new kitchen, double-glazing, new bathroom), we had a new
consumer unit fitted, located where the previous fusebox had been - out
in the garage.
The unit seems to be standard fare, with separate trips for ring main,
upstairs lighting, downstairs lighting and a 30 amp circuit for an
electric shower.
Some years ago, we started to get trouble from the Triton shower. When
set to its higher temperature, it would sometimes trip the consumer unit
off completely.
That wording suggests to me that it was tripping out multiple circuits
and not just the shower one. If so, it suggests that there is a whole
house RCD and that the shower has developed an electrical leak to earth.
Possibly there are two heating elements (one for low and both for high)
and the high element is failing.

If that is the case then replacing the shower should solve the problem.
However, we kept having trips and figured that the total leakage of all
our (lots) of electronic devices, with filters that permanently leak to
earth, was too high. We removed the RCD and replaced all the MCBs with
RCBOs, thus splitting the leakage across multiple circuits ... none have
tripped since.
JNugent
2024-05-14 00:03:32 UTC
Reply
Permalink
Post by SteveW
Post by JNugent
When we moved into this house just over thirty years ago, in addition
to all the usual (new kitchen, double-glazing, new bathroom), we had a
new consumer unit fitted, located where the previous fusebox had been
- out in the garage.
The unit seems to be standard fare, with separate trips for ring main,
upstairs lighting, downstairs lighting and a 30 amp circuit for an
electric shower.
Some years ago, we started to get trouble from the Triton shower. When
set to its higher temperature, it would sometimes trip the consumer
unit off completely.
That wording suggests to me that it was tripping out multiple circuits
and not just the shower one.
If used on the higher heating selection, that is what happened.
Post by SteveW
If so, it suggests that there is a whole
house RCD and that the shower has developed an electrical leak to earth.
Possibly there are two heating elements (one for low and both for high)
and the high element is failing.
It happened on the previous unit too. It was not Triton branded, but
made by Triton under another name and the equivalent of the Madrid II
model. I remember ringing Triton to get that information when the
previous one failed.
Post by SteveW
If that is the case then replacing the shower should solve the problem.
However, we kept having trips and figured that the total leakage of all
our (lots) of electronic devices, with filters that permanently leak to
earth, was too high. We removed the RCD and replaced all the MCBs with
RCBOs, thus splitting the leakage across multiple circuits ... none have
tripped since.
That sounds like something else which needs to be explored - thanks.
JNugent
2024-05-14 00:09:21 UTC
Reply
Permalink
Post by JNugent
Post by SteveW
Post by JNugent
When we moved into this house just over thirty years ago, in addition
to all the usual (new kitchen, double-glazing, new bathroom), we had
a new consumer unit fitted, located where the previous fusebox had
been - out in the garage.
The unit seems to be standard fare, with separate trips for ring
main, upstairs lighting, downstairs lighting and a 30 amp circuit for
an electric shower.
Some years ago, we started to get trouble from the Triton shower.
When set to its higher temperature, it would sometimes trip the
consumer unit off completely.
That wording suggests to me that it was tripping out multiple circuits
and not just the shower one.
If used on the higher heating selection, that is what happened.
Post by SteveW
If so, it suggests that there is a whole house RCD and that the shower
has developed an electrical leak to earth. Possibly there are two
heating elements (one for low and both for high) and the high element
is failing.
It happened on the previous unit too. It was not Triton branded, but
made by Triton under another name and the equivalent of the Madrid II
model. I remember ringing Triton to get that information when the
previous one failed.
[Addendum: That was to make sure that the water inlet and the wiring
were in the same place.]
Post by JNugent
Post by SteveW
If that is the case then replacing the shower should solve the
problem. However, we kept having trips and figured that the total
leakage of all our (lots) of electronic devices, with filters that
permanently leak to earth, was too high. We removed the RCD and
replaced all the MCBs with RCBOs, thus splitting the leakage across
multiple circuits ... none have tripped since.
That sounds like something else which needs to be explored - thanks.
Andy Burns
2024-05-14 06:14:12 UTC
Reply
Permalink
it suggests that there is a whole house RCD and that the shower has
developed an electrical leak to earth. Possibly there are two heating
elements (one for low and both for high) and the high element is
failing.
That was how I read it, until the part where the fault had persisted
across several shower replacements.
Fredxx
2024-05-14 10:54:54 UTC
Reply
Permalink
Post by JNugent
When we moved into this house just over thirty years ago, in addition to
all the usual (new kitchen, double-glazing, new bathroom), we had a new
consumer unit fitted, located where the previous fusebox had been - out
in the garage.
The unit seems to be standard fare, with separate trips for ring main,
upstairs lighting, downstairs lighting and a 30 amp circuit for an
electric shower.
Some years ago, we started to get trouble from the Triton shower. When
set to its higher temperature, it would sometimes trip the consumer unit
off completely. Apart from the general inconvenience of that, in those
days, the garage was only accessible from outdoors and if home alone,
resetting the unit would involve wrapping a wet body in towels and going
out into the back garden and into the garage's back door. Annoying or what?
On the lower temperature setting, the problem did not occur. Until
recently, though with the difference that only the shower trip cuts out
(and we now have a door from the house direct into the garage!).
This is the second or third Triton shower unit we've had in that 30+
years with the same results from the last two at least. For that reason,
my suspicion is that this is a fault at the consumer unit, and with the
shower trip in particular.
Yes, I am aware that I should have done something about it a few years
ago, but I certainly want to do it now. From experience, does this sound
like an issue where the remedy is a whole new consumer unit, please?
I hope it is...
Can you confirm only the RCD is being tripped and not the MCB as well?

Some RCDs can be over sensitive. It might be worth testing tripping
current, or if you don't have access to making the measurement, simply
change the RCD.
Paul
2024-05-14 11:27:24 UTC
Reply
Permalink
When we moved into this house just over thirty years ago, in addition to all the usual (new kitchen, double-glazing, new bathroom), we had a new consumer unit fitted, located where the previous fusebox had been - out in the garage.
The unit seems to be standard fare, with separate trips for ring main, upstairs lighting, downstairs lighting and a 30 amp circuit for an electric shower.
Some years ago, we started to get trouble from the Triton shower. When set to its higher temperature, it would sometimes trip the consumer unit off completely. Apart from the general inconvenience of that, in those days, the garage was only accessible from outdoors and if home alone, resetting the unit would involve wrapping a wet body in towels and going out into the back garden and into the garage's back door. Annoying or what?
On the lower temperature setting, the problem did not occur. Until recently, though with the difference that only the shower trip cuts out (and we now have a door from the house direct into the garage!).
This is the second or third Triton shower unit we've had in that 30+ years with the same results from the last two at least. For that reason, my suspicion is that this is a fault at the consumer unit, and with the shower trip in particular.
Yes, I am aware that I should have done something about it a few years ago, but I certainly want to do it now. From experience, does this sound like an issue where the remedy is a whole new consumer unit, please?
I hope it is...
One thing you should be aware of, with giant resistive loads
on house wiring... is your *line voltage*.

Say a particular gadget you bought, lists "3kW" on the rating plate.
That's 3kW at "nominal line voltage". The voltage at my house,
is always too high. This increases the current flow through resistive
loads. Suddenly, it's not a 3kW load any more.

This prevents me from running electric fires on "high".

Resistive heater loads, when the element is cold, they draw
even more current. It could be the initial presentation of
an ice cold shower load, which instead of 3kW, draws 3.5kW until
it starts to heat up. If the house line voltage is too high, the
initial power draw is now 4kW, and it settles down to about 3.5kW.
It would not drop to 3kW, unless the line voltage dropped to the
specified nominal value.

The protection device, may just be too close for the size of load,
and there is not enough margin. Several decades ago, a standard
electric water heater here, would have used a 15 amp breaker.
Today, they use a 20 amp breaker (just to avoid nuisance trips),
and the wire from the panel is gauged for 20 amps).

While your consumer unit could be faulty, a confluence of factors
could also account for nuisance trips.

Paul
The Natural Philosopher
2024-05-14 12:44:48 UTC
Reply
Permalink
Post by Paul
When we moved into this house just over thirty years ago, in addition to all the usual (new kitchen, double-glazing, new bathroom), we had a new consumer unit fitted, located where the previous fusebox had been - out in the garage.
The unit seems to be standard fare, with separate trips for ring main, upstairs lighting, downstairs lighting and a 30 amp circuit for an electric shower.
Some years ago, we started to get trouble from the Triton shower. When set to its higher temperature, it would sometimes trip the consumer unit off completely. Apart from the general inconvenience of that, in those days, the garage was only accessible from outdoors and if home alone, resetting the unit would involve wrapping a wet body in towels and going out into the back garden and into the garage's back door. Annoying or what?
On the lower temperature setting, the problem did not occur. Until recently, though with the difference that only the shower trip cuts out (and we now have a door from the house direct into the garage!).
This is the second or third Triton shower unit we've had in that 30+ years with the same results from the last two at least. For that reason, my suspicion is that this is a fault at the consumer unit, and with the shower trip in particular.
Yes, I am aware that I should have done something about it a few years ago, but I certainly want to do it now. From experience, does this sound like an issue where the remedy is a whole new consumer unit, please?
I hope it is...
One thing you should be aware of, with giant resistive loads
on house wiring... is your *line voltage*.
<sjip good stuff>

And a sudden application of a load on a rather high impedance line can
cause a step in voltage, which, when applied to a live-to-earth RF
filter capacitor can cause a current spike to earth.

Goodnight earth leakage trip...

Also, as i know to my cost, earth neutral shorts don't cause trips when
no current flows through them: High current causes neutral voltage drops
and then some electrons choose the earth route, tripping the RCD.

If you can, test the wiring for shorts when *completely isolated*.
--
There is nothing a fleet of dispatchable nuclear power plants cannot do
that cannot be done worse and more expensively and with higher carbon
emissions and more adverse environmental impact by adding intermittent
renewable energy.
Theo
2024-05-14 13:07:54 UTC
Reply
Permalink
Post by Paul
One thing you should be aware of, with giant resistive loads
on house wiring... is your *line voltage*.
Say a particular gadget you bought, lists "3kW" on the rating plate.
That's 3kW at "nominal line voltage". The voltage at my house,
is always too high. This increases the current flow through resistive
loads. Suddenly, it's not a 3kW load any more.
This prevents me from running electric fires on "high".
This shower has its 10.5kW rating at 240V for that reason, rather than the
nominal 230V. At 230V it takes 9.6kW:
https://www.tritonshowers.co.uk/amfile/file/download/file/277/product/431/

If the supply is up at 250+V then it could take more current than rated.
Post by Paul
Resistive heater loads, when the element is cold, they draw
even more current. It could be the initial presentation of
an ice cold shower load, which instead of 3kW, draws 3.5kW until
it starts to heat up. If the house line voltage is too high, the
initial power draw is now 4kW, and it settles down to about 3.5kW.
It would not drop to 3kW, unless the line voltage dropped to the
specified nominal value.
With this kind of shower, the inlet water is more or less a constant
temperature, aside from a short leg of room temperature water at startup.
There's some seasonal variation but once the water is flowing the
temperature the element sees is roughly the same throughout a shower. The
output temperature can vary based on changes in water flow (either
deliberate via the dial, or other taps/toilets/appliances in the house).
Post by Paul
The protection device, may just be too close for the size of load,
and there is not enough margin. Several decades ago, a standard
electric water heater here, would have used a 15 amp breaker.
Today, they use a 20 amp breaker (just to avoid nuisance trips),
and the wire from the panel is gauged for 20 amps).
Agreed, that's my best guess of what's happening.

Theo
John Rumm
2024-05-14 23:06:13 UTC
Reply
Permalink
Post by JNugent
When we moved into this house just over thirty years ago, in addition to
all the usual (new kitchen, double-glazing, new bathroom), we had a new
consumer unit fitted, located where the previous fusebox had been - out
in the garage.
The unit seems to be standard fare, with separate trips for ring main,
upstairs lighting, downstairs lighting and a 30 amp circuit for an
electric shower.
I think to give a more reasoned answer we could do with a bit more
detail about what devices are actually fitted to the CU, since the term
"trip" is a bit unclear.
Post by JNugent
Some years ago, we started to get trouble from the Triton shower. When
set to its higher temperature, it would sometimes trip the consumer unit
off completely.
A standard CU would have a "main switch" as its master control - there
is no trip capability with these - it is just a manual switch. So it
sounds like you may have a RCD[1] in the main switch position.

There was a time fitting "whole house" RCDs like this was common - since
it gave significant extra protection from electric shock. However it
also proved to give a much larger risk of nuisance trips, and it is
particularly inconvenient since you lose all "discrimination" - any
earth fault on any circuit will trip all circuits, not just the one with
the fault.

[1] https://wiki.diyfaq.org.uk/index.php/RCD
Post by JNugent
Apart from the general inconvenience of that, in those
days, the garage was only accessible from outdoors and if home alone,
resetting the unit would involve wrapping a wet body in towels and going
out into the back garden and into the garage's back door. Annoying or what?
On the lower temperature setting, the problem did not occur. Until
recently, though with the difference that only the shower trip cuts out
(and we now have a door from the house direct into the garage!).
Now if just the shower trip cuts out, it is likely that it is protected
by a normal MCB[2], or a RCBO[3] (unlikely given the age).

[2] https://wiki.diyfaq.org.uk/index.php/MCB
[3] https://wiki.diyfaq.org.uk/index.php/MCB#RCBO

Does the trip happen immediately when you select high power, or does it
take a moment before it trips?

Assuming it is a normal MCB it is either seeing too much load, or
getting too hot. (modern MCBs have two separate trip mechanisms - one is
thermal using a bi-metal strip that will respond to a combination of
current and time - too much for too long will cause it to trip. The
other trip is magnetic and uses a solenoid rigs to snap open the switch
"instantly" when seeing a current surge above a certain threshold)

So either the shower is drawing too much current for the MCB, or there
is a loose connection near it that is getting hot and heating the whole
MCB - in effect sensitising it so that it trips at a lower current than
intended.

A 30A MCB would only support a 7kW shower. If the unit has been replaced
in the past, could it have been replaced with a more powerful model?

(In reality a 30A MCB would support a small overload for a fairly long
period of time)
Post by JNugent
This is the second or third Triton shower unit we've had in that 30+
years with the same results from the last two at least. For that reason,
my suspicion is that this is a fault at the consumer unit, and with the
shower trip in particular.
It is worth checking for signs of over heating, and also checking the
terminations on the shower circuit are still good and tight.

A photo of the CU so that we can see the devices fitted might help.
Post by JNugent
Yes, I am aware that I should have done something about it a few years
ago, but I certainly want to do it now. From experience, does this sound
like an issue where the remedy is a whole new consumer unit, please?
I hope it is...
It may not need a whole new CU (although there may be other reasons why
you might want one), but it sounds like some diagnosis and testing is in
order to find out what is actually happening.

See also:

https://wiki.diyfaq.org.uk/index.php/Changing_a_consumer_unit#Reasons_for_a_change


https://wiki.diyfaq.org.uk/index.php/Consumer_unit
https://wiki.diyfaq.org.uk/index.php/17th_Edition_Consumer_Units
--
Cheers,

John.

/=================================================================\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\=================================================================/
Smolley
2024-05-15 07:18:04 UTC
Reply
Permalink
Post by John Rumm
Post by JNugent
When we moved into this house just over thirty years ago, in addition
to all the usual (new kitchen, double-glazing, new bathroom), we had a
new consumer unit fitted, located where the previous fusebox had been -
out in the garage.
The unit seems to be standard fare, with separate trips for ring main,
upstairs lighting, downstairs lighting and a 30 amp circuit for an
electric shower.
I think to give a more reasoned answer we could do with a bit more
detail about what devices are actually fitted to the CU, since the term
"trip" is a bit unclear.
Post by JNugent
Some years ago, we started to get trouble from the Triton shower. When
set to its higher temperature, it would sometimes trip the consumer
unit off completely.
A standard CU would have a "main switch" as its master control - there
is no trip capability with these - it is just a manual switch. So it
sounds like you may have a RCD[1] in the main switch position.
There was a time fitting "whole house" RCDs like this was common - since
it gave significant extra protection from electric shock. However it
also proved to give a much larger risk of nuisance trips, and it is
particularly inconvenient since you lose all "discrimination" - any
earth fault on any circuit will trip all circuits, not just the one with
the fault.
[1] https://wiki.diyfaq.org.uk/index.php/RCD
Post by JNugent
Apart from the general inconvenience of that, in those days, the garage
was only accessible from outdoors and if home alone, resetting the unit
would involve wrapping a wet body in towels and going out into the back
garden and into the garage's back door. Annoying or what?
On the lower temperature setting, the problem did not occur. Until
recently, though with the difference that only the shower trip cuts out
(and we now have a door from the house direct into the garage!).
Now if just the shower trip cuts out, it is likely that it is protected
by a normal MCB[2], or a RCBO[3] (unlikely given the age).
[2] https://wiki.diyfaq.org.uk/index.php/MCB [3]
https://wiki.diyfaq.org.uk/index.php/MCB#RCBO
Does the trip happen immediately when you select high power, or does it
take a moment before it trips?
Assuming it is a normal MCB it is either seeing too much load, or
getting too hot. (modern MCBs have two separate trip mechanisms - one is
thermal using a bi-metal strip that will respond to a combination of
current and time - too much for too long will cause it to trip. The
other trip is magnetic and uses a solenoid rigs to snap open the switch
"instantly" when seeing a current surge above a certain threshold)
So either the shower is drawing too much current for the MCB, or there
is a loose connection near it that is getting hot and heating the whole
MCB - in effect sensitising it so that it trips at a lower current than
intended.
A 30A MCB would only support a 7kW shower. If the unit has been replaced
in the past, could it have been replaced with a more powerful model?
(In reality a 30A MCB would support a small overload for a fairly long
period of time)
Post by JNugent
This is the second or third Triton shower unit we've had in that 30+
years with the same results from the last two at least. For that
reason, my suspicion is that this is a fault at the consumer unit, and
with the shower trip in particular.
It is worth checking for signs of over heating, and also checking the
terminations on the shower circuit are still good and tight.
A photo of the CU so that we can see the devices fitted might help.
Post by JNugent
Yes, I am aware that I should have done something about it a few years
ago, but I certainly want to do it now. From experience, does this
sound like an issue where the remedy is a whole new consumer unit,
please?
I hope it is...
It may not need a whole new CU (although there may be other reasons why
you might want one), but it sounds like some diagnosis and testing is in
order to find out what is actually happening.
https://wiki.diyfaq.org.uk/index.php/
Changing_a_consumer_unit#Reasons_for_a_change
Post by John Rumm
https://wiki.diyfaq.org.uk/index.php/Consumer_unit
https://wiki.diyfaq.org.uk/index.php/17th_Edition_Consumer_Units
I have a 30ma 'trip' on the Consumer Unit main switch.
John Rumm
2024-05-15 12:26:44 UTC
Reply
Permalink
Post by Smolley
I have a 30ma 'trip' on the Consumer Unit main switch.
A so called "whole house" RCD - long since deprecated, but you are
certainly not alone in still having an installation like that.
--
Cheers,

John.

/=================================================================\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\=================================================================/
charles
2024-05-15 14:30:03 UTC
Reply
Permalink
Post by John Rumm
Post by Smolley
I have a 30ma 'trip' on the Consumer Unit main switch.
A so called "whole house" RCD - long since deprecated, but you are
certainly not alone in still having an installation like that.
I have one - quite normal in the late 1970s.
--
from KT24 in Surrey, England - sent from my RISC OS 4té²
"I'd rather die of exhaustion than die of boredom" Thomas Carlyle
JNugent
2024-05-15 14:55:46 UTC
Reply
Permalink
Even more thanks for all these helpful responses.

I'm going to have it all looked at by a professional!
Andy Burns
2024-05-15 15:22:29 UTC
Reply
Permalink
Post by charles
Post by John Rumm
A so called "whole house" RCD - long since deprecated, but you are
certainly not alone in still having an installation like that.
I have one - quite normal in the late 1970s.
In the '70s more likely to be a huge VOELCB, rather than an RCD
charles
2024-05-15 16:00:03 UTC
Reply
Permalink
Post by Andy Burns
Post by charles
Post by John Rumm
A so called "whole house" RCD - long since deprecated, but you are
certainly not alone in still having an installation like that.
I have one - quite normal in the late 1970s.
In the '70s more likely to be a huge VOELCB, rather than an RCD
No, it's an RCD - it says so on it. Made by MK.
--
from KT24 in Surrey, England - sent from my RISC OS 4té²
"I'd rather die of exhaustion than die of boredom" Thomas Carlyle
Smolley
2024-05-15 17:39:50 UTC
Reply
Permalink
Post by charles
Post by John Rumm
Post by Smolley
I have a 30ma 'trip' on the Consumer Unit main switch.
A so called "whole house" RCD - long since deprecated, but you are
certainly not alone in still having an installation like that.
I have one - quite normal in the late 1970s.
My house was built 1993.
David Wade
2024-05-15 16:13:43 UTC
Reply
Permalink
Post by John Rumm
Post by Smolley
I have a 30ma 'trip' on the Consumer Unit main switch.
A so called "whole house" RCD - long since deprecated, but you are
certainly not alone in still having an installation like that.
So showing the stupidity of the wiring regulations which permit old
installations to remain in place even though they have long been obsolete...

Dave
Alan Lee
2024-05-15 17:34:02 UTC
Reply
Permalink
Post by David Wade
Post by John Rumm
A so called "whole house" RCD - long since deprecated, but you are
certainly not alone in still having an installation like that.
So showing the stupidity of the wiring regulations which permit old
installations to remain in place even though they have long been obsolete...
Why's that then?
They havent been made obsolete, just that better ways are now available.
If it trips, its a nuisance as all power is lost, but it isnt unsafe.
David Wade
2024-05-15 17:58:17 UTC
Reply
Permalink
Post by Alan Lee
Post by David Wade
Post by John Rumm
A so called "whole house" RCD - long since deprecated, but you are
certainly not alone in still having an installation like that.
So showing the stupidity of the wiring regulations which permit old
installations to remain in place even though they have long been obsolete...
Why's that then?
They havent been made obsolete, just that better ways are now available.
If it trips, its a nuisance as all power is lost, but it isnt unsafe.
Depends on your definition of "safe". If it trips in the middle of the
night you are left with no power and no light. Of course you should have
a torch but have recently had a hard trip due to water ingress on my
split board which persisted even though the MCB was off, I would suggest
this could be very very inconvenient...

Dave
SteveW
2024-05-15 19:09:46 UTC
Reply
Permalink
Post by David Wade
Post by Alan Lee
Post by David Wade
Post by John Rumm
A so called "whole house" RCD - long since deprecated, but you are
certainly not alone in still having an installation like that.
So showing the stupidity of the wiring regulations which permit old
installations to remain in place even though they have long been obsolete...
Why's that then?
They havent been made obsolete, just that better ways are now available.
If it trips, its a nuisance as all power is lost, but it isnt unsafe.
Depends on your definition of "safe". If it trips in the middle of the
night you are left with no power and no light. Of course you should have
a torch but have recently had a hard trip due to water ingress on my
split board which persisted even though the MCB was off, I would suggest
this could be very very inconvenient...
In houses with a whole house RCD (except for TT systems), the lights
would not have been put under the RCD protection.

Later, dual-RCD, installations should have had the lights on the
opposite RCD to the sockets for each floor, so tripping of the lights on
one floor would still allow a table lamp, TV or suchlike to give some light.
charles
2024-05-15 19:45:02 UTC
Reply
Permalink
Post by SteveW
Post by David Wade
Post by David Wade
Post by John Rumm
A so called "whole house" RCD - long since deprecated, but you are
certainly not alone in still having an installation like that.
So showing the stupidity of the wiring regulations which permit old
installations to remain in place even though they have long been obsolete...
Why's that then? They havent been made obsolete, just that better ways
are now available. If it trips, its a nuisance as all power is lost,
but it isnt unsafe.
Depends on your definition of "safe". If it trips in the middle of the
night you are left with no power and no light. Of course you should
have a torch but have recently had a hard trip due to water ingress on
my split board which persisted even though the MCB was off, I would
suggest this could be very very inconvenient...
In houses with a whole house RCD (except for TT systems), the lights
would not have been put under the RCD protection.
No, with a whole house RCD, there is just the one master switch ie the RCD
- everything is on it,
Post by SteveW
Later, dual-RCD, installations should have had the lights on the
opposite RCD to the sockets for each floor, so tripping of the lights on
one floor would still allow a table lamp, TV or suchlike to give some light.
--
from KT24 in Surrey, England - sent from my RISC OS 4té²
"I'd rather die of exhaustion than die of boredom" Thomas Carlyle
SteveW
2024-05-16 08:40:12 UTC
Reply
Permalink
Post by charles
Post by SteveW
Post by David Wade
Post by David Wade
Post by John Rumm
A so called "whole house" RCD - long since deprecated, but you are
certainly not alone in still having an installation like that.
So showing the stupidity of the wiring regulations which permit old
installations to remain in place even though they have long been obsolete...
Why's that then? They havent been made obsolete, just that better ways
are now available. If it trips, its a nuisance as all power is lost,
but it isnt unsafe.
Depends on your definition of "safe". If it trips in the middle of the
night you are left with no power and no light. Of course you should
have a torch but have recently had a hard trip due to water ingress on
my split board which persisted even though the MCB was off, I would
suggest this could be very very inconvenient...
In houses with a whole house RCD (except for TT systems), the lights
would not have been put under the RCD protection.
No, with a whole house RCD, there is just the one master switch ie the RCD
- everything is on it,
Most only covered a subset of the MCBs, with lighting, house alarms and,
sometimes, dedicated freezer supplies not covered by the RCD.
The Natural Philosopher
2024-05-16 09:04:23 UTC
Reply
Permalink
Post by SteveW
Post by charles
Post by SteveW
Post by David Wade
Post by David Wade
Post by John Rumm
A so called "whole house" RCD - long since deprecated, but you are
certainly not alone in still having an installation like that.
So showing the stupidity of the wiring regulations which permit old
installations to remain in place even though they have long been obsolete...
Why's that then? They havent been made obsolete, just that better ways
are now available. If it trips, its a nuisance as all power is lost,
but it isnt unsafe.
Depends on your definition of "safe". If it trips in the middle of the
night you are left with no power and no light. Of course you should
have a torch but have recently had a hard trip due to water ingress on
my split board which persisted even though the MCB was off, I would
suggest this could be very very inconvenient...
In houses with a whole house RCD (except for TT systems), the lights
would not have been put under the RCD protection.
No, with a whole house RCD, there is just the one master switch ie the RCD
- everything is on it,
Most only covered a subset of the MCBs, with lighting, house alarms and,
sometimes, dedicated freezer supplies not covered by the RCD.
No. Always it was the main breaker for all the incoming electrons. By
the 80s anyway
--
Labour - a bunch of rich people convincing poor people to vote for rich
people by telling poor people that "other" rich people are the reason
they are poor.

Peter Thompson
SteveW
2024-05-16 09:24:22 UTC
Reply
Permalink
Post by SteveW
Post by charles
Post by SteveW
Post by David Wade
Post by David Wade
Post by John Rumm
A so called "whole house" RCD - long since deprecated, but you are
certainly not alone in still having an installation like that.
So showing the stupidity of the wiring regulations which permit old
installations to remain in place even though they have long been obsolete...
Why's that then? They havent been made obsolete, just that better ways
are now available. If it trips, its a nuisance as all power is lost,
but it isnt unsafe.
Depends on your definition of "safe". If it trips in the middle of the
night you are left with no power and no light. Of course you should
have a torch but have recently had a hard trip due to water ingress on
my split board which persisted even though the MCB was off, I would
suggest this could be very very inconvenient...
In houses with a whole house RCD (except for TT systems), the lights
would not have been put under the RCD protection.
No, with a whole house RCD, there is just the one master switch ie the RCD
- everything is on it,
Most only covered a subset of the MCBs, with lighting, house alarms
and, sometimes, dedicated freezer supplies not covered by the RCD.
No. Always it was the main breaker for all the incoming  electrons. By
the 80s anyway
Surely in the '80s and '90s, the norm was for the supply to go straight
from the meter to the CU main switch and to have a split load busbar,
with RCD protection for part of it? Using an RCD instead of a main
switch only came in later? Likely with dual RCB CUs.
Alan Lee
2024-05-16 14:59:33 UTC
Reply
Permalink
Post by SteveW
Most only covered a subset of the MCBs, with lighting, house alarms
and, sometimes, dedicated freezer supplies not covered by the RCD.
No. Always it was the main breaker for all the incoming  electrons. By
the 80s anyway
Only if it was a TT supply. RCDs were rare in the 80's, it was the early
90's before they became commercially available at a reasonable price
here, when the 16th (1991) was introduced, was the first time they were
generally used.

For TN-S/TN-C-S supplies, it would have the main switch, with ,
generally, socket/shower circuits on the RCD, with lighting and others
on the non-RCD side. It was called a 16th edition board then (1991 onward).
17th Edition,2008, pretty much put all circuits on RCDs, but on split
RCDs, so 2 RCDs in the consumer unit.

Before the 16th Edition, there could have been a VOELCB device upfront,
which measures the voltage to earth. These are superceded, and should be
replaced now, as they are nowhere near as safe as RCDs, and give a false
sense of security, as they will not trip if a fault goes to earth via
any other path other than the earth connection to the VOELCB.
Andrew
2024-05-15 19:50:53 UTC
Reply
Permalink
Post by SteveW
Post by David Wade
Post by Alan Lee
Post by David Wade
Post by John Rumm
A so called "whole house" RCD - long since deprecated, but you are
certainly not alone in still having an installation like that.
So showing the stupidity of the wiring regulations which permit old
installations to remain in place even though they have long been obsolete...
Why's that then?
They havent been made obsolete, just that better ways are now available.
If it trips, its a nuisance as all power is lost, but it isnt unsafe.
Depends on your definition of "safe". If it trips in the middle of the
night you are left with no power and no light. Of course you should
have a torch but have recently had a hard trip due to water ingress on
my split board which persisted even though the MCB was off, I would
suggest this could be very very inconvenient...
In houses with a whole house RCD (except for TT systems), the lights
would not have been put under the RCD protection.
Err, not necessarily. Parents house was built in 1956 on land
to the side of the bungalow where we lived.

Lighting circuits had no cpc, so when my step mother decided that
the original 'Shell' wall lights 'had' to be replaced with horrid
metal replacements the electrician correctly added a whole house
RCD to the existing old-fashioned fuse board. This was not a
problem until they started using Tesco bulbs instead of decent
quality Osram or whatever and were occasionally plunged into
darkness when a bulb blew.
The Natural Philosopher
2024-05-15 19:53:38 UTC
Reply
Permalink
Post by SteveW
In houses with a whole house RCD (except for TT systems), the lights
would not have been put under the RCD protection.
They were.
It was whole house.

Mine still is, though it has a 100mA trip in it. I must put RCBOs in
before I die.
Post by SteveW
Later, dual-RCD, installations should have had the lights on the
opposite RCD to the sockets for each floor, so tripping of the lights on
one floor would still allow a table lamp, TV or suchlike to give some light.
--
Microsoft : the best reason to go to Linux that ever existed.
SteveW
2024-05-16 09:08:35 UTC
Reply
Permalink
Post by The Natural Philosopher
Post by SteveW
In houses with a whole house RCD (except for TT systems), the lights
would not have been put under the RCD protection.
They were.
It was whole house.
Mine still is, though it has a 100mA trip in it. I must put RCBOs in
before I die.
What system are you on? 100mA RCD for TT systems are normal. They may
also be fitted for Non-TT system, but are usually not and not normally a
requirement.

In either case, when 30mA RCDs began to be used as well, for protection
of life, they usually only covered circuits other than lighting (hence
the use of split-load consumer units, with a single RCD), until dual RCD
boards became the norm.

IIRC the 16th edition regulations required a single RCD, covering
sockets likely to be used for powering equipment outside, which was
gradually considered to be most sockets. Often, everything but the
lights (certainly all the sockets) was covered by the RCD and it was
considered a whole house RCD. Mine had lights and alarm unprotected.

17th required twin RCDs, with everything split between them and lighting
on the opposite RCD to the sockets in that area.

18th edition hasn't really changed that although there has been more
emphasis in guidance on not tripping multiple circuits and so a general
move towards RCBOs.

I suppose as prices come down, there will be a shift from RCBOs to AFDDs
- which are already required in some circumatances.
The Natural Philosopher
2024-05-16 09:53:35 UTC
Reply
Permalink
Post by SteveW
Post by The Natural Philosopher
Post by SteveW
In houses with a whole house RCD (except for TT systems), the lights
would not have been put under the RCD protection.
They were.
It was whole house.
Mine still is, though it has a 100mA trip in it. I must put RCBOs in
before I die.
What system are you on? 100mA RCD for TT systems are normal. They may
also be fitted for Non-TT system, but are usually not and not normally a
requirement.
Fuck knows. They ran a coax cable from the big transformer in the garden
and said use that as earth, but I already had a big copper stake so I
used that as well
Post by SteveW
In either case, when 30mA RCDs began to be used as well, for protection
of life, they usually only covered circuits other than lighting (hence
the use of split-load consumer units, with a single RCD), until dual RCD
boards became the norm.
IIRC the 16th edition regulations required a single RCD, covering
sockets likely to be used for powering equipment outside, which was
gradually considered to be most sockets. Often, everything but the
lights (certainly all the sockets) was covered by the RCD and it was
considered a whole house RCD. Mine had lights and alarm unprotected.
17th required twin RCDs, with everything split between them and lighting
on the opposite RCD to the sockets in that area.
18th edition hasn't really changed that although there has been more
emphasis in guidance on not tripping multiple circuits and so a general
move towards RCBOs.
I suppose as prices come down, there will be a shift from RCBOs to AFDDs
- which are already required in some circumatances.
Id go full RCBO if money and space permitted
--
In todays liberal progressive conflict-free education system, everyone
gets full Marx.
Chris Hogg
2024-05-16 16:05:35 UTC
Reply
Permalink
On Thu, 16 May 2024 10:53:35 +0100, The Natural Philosopher
Post by The Natural Philosopher
Id go full RCBO if money and space permitted
When this bungalow was being modernised six years ago, including
re-wiring and a new CU, I specified RCBO's on all the circuits. I have
seven: two B6's for two lighting circuits, a B16 for the immersion
heater, a B20 for the gas boiler and C/H, two B32's (sockets, kitchen
and garage, and sockets rest of the bungalow) and a B40 for the
cooker.
--
Chris
The Natural Philosopher
2024-05-16 17:11:08 UTC
Reply
Permalink
Post by Chris Hogg
On Thu, 16 May 2024 10:53:35 +0100, The Natural Philosopher
Post by The Natural Philosopher
Id go full RCBO if money and space permitted
When this bungalow was being modernised six years ago, including
re-wiring and a new CU, I specified RCBO's on all the circuits. I have
seven: two B6's for two lighting circuits, a B16 for the immersion
heater, a B20 for the gas boiler and C/H, two B32's (sockets, kitchen
and garage, and sockets rest of the bungalow) and a B40 for the
cooker.
I think I have around 16 breakers in my CU :-(
--
"And if the blind lead the blind, both shall fall into the ditch".

Gospel of St. Mathew 15:14
Andrew
2024-05-19 13:54:40 UTC
Reply
Permalink
Post by Chris Hogg
On Thu, 16 May 2024 10:53:35 +0100, The Natural Philosopher
Post by The Natural Philosopher
Id go full RCBO if money and space permitted
When this bungalow was being modernised six years ago, including
re-wiring and a new CU, I specified RCBO's on all the circuits. I have
seven: two B6's for two lighting circuits, a B16 for the immersion
heater, a B20 for the gas boiler and C/H, two B32's (sockets, kitchen
and garage, and sockets rest of the bungalow) and a B40 for the
cooker.
Oh dear. Type AC RCD's and ?RCBO's are now banned.

watch out for a sparky telling you that they are illegal and must be
replaced by type A devices (which are said to be resistant to locking
up due to DC saturating the iron core, or something like that).

If you ever get an EV then I think it will need to have its own
RCD protected feed and this will have to be a type A device, but I'm
not sure if all the others would need changing. Someone with knowledge
of rev 18 will be along shortly to explain.
SteveW
2024-05-19 14:12:19 UTC
Reply
Permalink
Post by Andrew
Post by Chris Hogg
On Thu, 16 May 2024 10:53:35 +0100, The Natural Philosopher
Post by The Natural Philosopher
Id go full RCBO if money and space permitted
When this bungalow was being modernised six years ago, including
re-wiring and a new CU, I specified RCBO's on all the circuits. I have
seven: two B6's for two lighting circuits, a B16 for the immersion
heater, a B20 for the gas boiler and C/H, two B32's (sockets, kitchen
and garage, and sockets rest of the bungalow) and a B40 for the
cooker.
Oh dear. Type AC RCD's and ?RCBO's are now banned.
watch out for a sparky telling you that they are illegal and must be
replaced by type A devices (which are said to be resistant to locking
up due to DC saturating the iron core, or something like that).
If you ever get an EV then I think it will need to have its own
RCD protected feed and this will have to be a type A device.
Not necessarily.

We had an EV charger installed last year. The charger manufacturer's
normal requirement is just an isolator and a double-pole MCB in its own
enclosure, with no need for an RCD or RCBO external to the charger
itself; the cable was run inside the electricity box and then through
the wall to the back of the charger, therefore there was no wiring
regulations requirement for an RCD on that; if an external run or a
shallow internal channel was required, the installer would have used
cable with built-in mechanical protection, so again, no need for an RCD.

However, I did not want the extra enclosure, plus Henley blocks and
extra tails and preferred the cable straight into our existing CU. By
using an RCBO rather than a double-pole MCB, I obtained the required
overcurrent protection and double-pole isolation, while using only a
single slot - the RCD part of the RCBO is not actually required at all.
Post by Andrew
but I'm
not sure if all the others would need changing. Someone with knowledge
of rev 18 will be along shortly to explain.
Wiring Regulations are not retrospective - there's no need to have any
RCDs or RCBOs on an older installation. Changes to that installation may
require upgrades at the CU though.
Andrew
2024-05-19 14:17:53 UTC
Reply
Permalink
Post by SteveW
Post by Andrew
Post by Chris Hogg
On Thu, 16 May 2024 10:53:35 +0100, The Natural Philosopher
Post by The Natural Philosopher
Id go full RCBO if money and space permitted
When this bungalow was being modernised six years ago, including
re-wiring and a new CU, I specified RCBO's on all the circuits. I have
seven: two B6's for two lighting circuits, a B16 for the immersion
heater, a B20 for the gas boiler and C/H, two B32's (sockets, kitchen
and garage, and sockets rest of the bungalow) and a B40 for the
cooker.
Oh dear. Type AC RCD's and ?RCBO's are now banned.
watch out for a sparky telling you that they are illegal and must be
replaced by type A devices (which are said to be resistant to locking
up due to DC saturating the iron core, or something like that).
If you ever get an EV then I think it will need to have its own
RCD protected feed and this will have to be a type A device.
Not necessarily.
We had an EV charger installed last year. The charger manufacturer's
normal requirement is just an isolator and a double-pole MCB in its own
enclosure, with no need for an RCD or RCBO external to the charger
itself; the cable was run inside the electricity box and then through
the wall to the back of the charger, therefore there was no wiring
regulations requirement for an RCD on that; if an external run or a
shallow internal channel was required, the installer would have used
cable with built-in mechanical protection, so again, no need for an RCD.
However, I did not want the extra enclosure, plus Henley blocks and
extra tails and preferred the cable straight into our existing CU. By
using an RCBO rather than a double-pole MCB, I obtained the required
overcurrent protection and double-pole isolation, while using only a
single slot - the RCD part of the RCBO is not actually required at all.
Post by Andrew
but I'm
not sure if all the others would need changing. Someone with knowledge
of rev 18 will be along shortly to explain.
Wiring Regulations are not retrospective - there's no need to have any
RCDs or RCBOs on an older installation. Changes to that installation may
require upgrades at the CU though.
https://www.doepke.co.uk/downloads/Techpubs/Techpub-06.pdf
Theo
2024-05-19 17:29:38 UTC
Reply
Permalink
Post by Andrew
Post by SteveW
Post by Andrew
but I'm
not sure if all the others would need changing. Someone with knowledge
of rev 18 will be along shortly to explain.
Wiring Regulations are not retrospective - there's no need to have any
RCDs or RCBOs on an older installation. Changes to that installation may
require upgrades at the CU though.
https://www.doepke.co.uk/downloads/Techpubs/Techpub-06.pdf
Type B RCDs are still ridiculously expensive (for reasons I don't really
understand), so most EVSEs go for a Type A plus a current transformer around
the car tails. Any imbalance and the EVSE cuts the power. They also
monitor the line-neutral voltage and cut it if out of range, which would
suggest a PEN fault.

This is a DIY EVSE from the Netherlands, but gives the general wiring idea:
Loading Image...
There are relays on the mainboard that cut the power if anything is unhappy.

Theo
Andrew
2024-05-20 08:24:50 UTC
Reply
Permalink
Post by Theo
Post by Andrew
Post by SteveW
Post by Andrew
but I'm
not sure if all the others would need changing. Someone with knowledge
of rev 18 will be along shortly to explain.
Wiring Regulations are not retrospective - there's no need to have any
RCDs or RCBOs on an older installation. Changes to that installation may
require upgrades at the CU though.
https://www.doepke.co.uk/downloads/Techpubs/Techpub-06.pdf
Type B RCDs are still ridiculously expensive (for reasons I don't really
understand), so most EVSEs go for a Type A plus a current transformer around
the car tails. Any imbalance and the EVSE cuts the power. They also
monitor the line-neutral voltage and cut it if out of range, which would
suggest a PEN fault.
https://github.com/edge-tech-eu/SmartEVSE/blob/main/installation/aansluiten-dubbele-laadmodule.png
There are relays on the mainboard that cut the power if anything is unhappy.
Theo
According to that picture, the Netherlands has not adopted
harmonised colours for 3-phase, which is strange.
Andy Burns
2024-05-20 08:53:30 UTC
Reply
Permalink
Post by Andrew
According to that picture, the Netherlands has not adopted
harmonised colours for 3-phase, which is strange.
looks like (slightly off hue shades of) brown, black, grey and blue to
me ...
SteveW
2024-05-20 09:11:14 UTC
Reply
Permalink
Post by Andrew
Post by SteveW
Post by Andrew
Post by Chris Hogg
On Thu, 16 May 2024 10:53:35 +0100, The Natural Philosopher
Post by The Natural Philosopher
Id go full RCBO if money and space permitted
When this bungalow was being modernised six years ago, including
re-wiring and a new CU, I specified RCBO's on all the circuits. I have
seven: two B6's for two lighting circuits, a B16 for the immersion
heater, a B20 for the gas boiler and C/H, two B32's (sockets, kitchen
and garage, and sockets rest of the bungalow) and a B40 for the
cooker.
Oh dear. Type AC RCD's and ?RCBO's are now banned.
watch out for a sparky telling you that they are illegal and must be
replaced by type A devices (which are said to be resistant to locking
up due to DC saturating the iron core, or something like that).
If you ever get an EV then I think it will need to have its own
RCD protected feed and this will have to be a type A device.
Not necessarily.
We had an EV charger installed last year. The charger manufacturer's
normal requirement is just an isolator and a double-pole MCB in its
own enclosure, with no need for an RCD or RCBO external to the charger
itself; the cable was run inside the electricity box and then through
the wall to the back of the charger, therefore there was no wiring
regulations requirement for an RCD on that; if an external run or a
shallow internal channel was required, the installer would have used
cable with built-in mechanical protection, so again, no need for an RCD.
However, I did not want the extra enclosure, plus Henley blocks and
extra tails and preferred the cable straight into our existing CU. By
using an RCBO rather than a double-pole MCB, I obtained the required
overcurrent protection and double-pole isolation, while using only a
single slot - the RCD part of the RCBO is not actually required at all.
Post by Andrew
but I'm
not sure if all the others would need changing. Someone with knowledge
of rev 18 will be along shortly to explain.
Wiring Regulations are not retrospective - there's no need to have any
RCDs or RCBOs on an older installation. Changes to that installation
may require upgrades at the CU though.
https://www.doepke.co.uk/downloads/Techpubs/Techpub-06.pdf
Many EV chargers now incorporate the required protection within the
charger, removing the need for feeding it from an external RCD.
Andrew
2024-05-20 09:21:34 UTC
Reply
Permalink
Post by SteveW
Post by Andrew
Post by SteveW
Post by Andrew
Post by Chris Hogg
On Thu, 16 May 2024 10:53:35 +0100, The Natural Philosopher
Post by The Natural Philosopher
Id go full RCBO if money and space permitted
When this bungalow was being modernised six years ago, including
re-wiring and a new CU, I specified RCBO's on all the circuits. I have
seven: two B6's for two lighting circuits, a B16 for the immersion
heater, a B20 for the gas boiler and C/H, two B32's (sockets, kitchen
and garage, and sockets rest of the bungalow) and a B40 for the
cooker.
Oh dear. Type AC RCD's and ?RCBO's are now banned.
watch out for a sparky telling you that they are illegal and must be
replaced by type A devices (which are said to be resistant to locking
up due to DC saturating the iron core, or something like that).
If you ever get an EV then I think it will need to have its own
RCD protected feed and this will have to be a type A device.
Not necessarily.
We had an EV charger installed last year. The charger manufacturer's
normal requirement is just an isolator and a double-pole MCB in its
own enclosure, with no need for an RCD or RCBO external to the
charger itself; the cable was run inside the electricity box and then
through the wall to the back of the charger, therefore there was no
wiring regulations requirement for an RCD on that; if an external run
or a shallow internal channel was required, the installer would have
used cable with built-in mechanical protection, so again, no need for
an RCD.
However, I did not want the extra enclosure, plus Henley blocks and
extra tails and preferred the cable straight into our existing CU. By
using an RCBO rather than a double-pole MCB, I obtained the required
overcurrent protection and double-pole isolation, while using only a
single slot - the RCD part of the RCBO is not actually required at all.
Post by Andrew
but I'm
not sure if all the others would need changing. Someone with knowledge
of rev 18 will be along shortly to explain.
Wiring Regulations are not retrospective - there's no need to have
any RCDs or RCBOs on an older installation. Changes to that
installation may require upgrades at the CU though.
https://www.doepke.co.uk/downloads/Techpubs/Techpub-06.pdf
Many EV chargers now incorporate the required protection within the
charger, removing the need for feeding it from an external RCD.
It's not just EV's though. Houses are full of modern stuff
like PC's and LED bulbs etc. which are claimed to have the
capability of imposing DC on the AC mains.
Theo
2024-05-20 11:06:35 UTC
Reply
Permalink
Post by Andrew
Post by SteveW
Post by Andrew
https://www.doepke.co.uk/downloads/Techpubs/Techpub-06.pdf
Many EV chargers now incorporate the required protection within the
charger, removing the need for feeding it from an external RCD.
It's not just EV's though. Houses are full of modern stuff
like PC's and LED bulbs etc. which are claimed to have the
capability of imposing DC on the AC mains.
Yes, Doepke (who make RCDs) marketing are very keen to point out that fact,
placing 'advertorials' in trade publications as why you need to fit fancy
RCDs/RCBOs everywhere:

https://essmag.co.uk/ev-charging-selectivity-between-rcds/
https://electricalcontractingnews.com/news/heat-pumps-type-f-or-type-b-rcds/

Now if they would make their Type B RCBOs £20 not £200 then they might be an
option. Meanwhile the EV charger vendors go for the Type A+monitoring
because it's a lot cheaper than a Type B.

(To add to the confusion, many sellers of RCBOs list them as 'Type B' when
they actually mean 'B-curve', the trip current curve for the MCB side of
things. That has nothing to do with DC rejection - those usually contain
Type AC RCDs)

Theo
SteveW
2024-05-20 12:09:43 UTC
Reply
Permalink
Post by Andrew
Post by SteveW
Post by Andrew
Post by SteveW
Post by Andrew
Post by Chris Hogg
On Thu, 16 May 2024 10:53:35 +0100, The Natural Philosopher
Post by The Natural Philosopher
Id go full RCBO if money and space permitted
When this bungalow was being modernised six years ago, including
re-wiring and a new CU, I specified RCBO's on all the circuits. I have
seven: two B6's for two lighting circuits, a B16 for the immersion
heater, a B20 for the gas boiler and C/H, two B32's (sockets, kitchen
and garage, and sockets rest of the bungalow) and a B40 for the
cooker.
Oh dear. Type AC RCD's and ?RCBO's are now banned.
watch out for a sparky telling you that they are illegal and must be
replaced by type A devices (which are said to be resistant to locking
up due to DC saturating the iron core, or something like that).
If you ever get an EV then I think it will need to have its own
RCD protected feed and this will have to be a type A device.
Not necessarily.
We had an EV charger installed last year. The charger manufacturer's
normal requirement is just an isolator and a double-pole MCB in its
own enclosure, with no need for an RCD or RCBO external to the
charger itself; the cable was run inside the electricity box and
then through the wall to the back of the charger, therefore there
was no wiring regulations requirement for an RCD on that; if an
external run or a shallow internal channel was required, the
installer would have used cable with built-in mechanical protection,
so again, no need for an RCD.
However, I did not want the extra enclosure, plus Henley blocks and
extra tails and preferred the cable straight into our existing CU.
By using an RCBO rather than a double-pole MCB, I obtained the
required overcurrent protection and double-pole isolation, while
using only a single slot - the RCD part of the RCBO is not actually
required at all.
Post by Andrew
but I'm
not sure if all the others would need changing. Someone with knowledge
of rev 18 will be along shortly to explain.
Wiring Regulations are not retrospective - there's no need to have
any RCDs or RCBOs on an older installation. Changes to that
installation may require upgrades at the CU though.
https://www.doepke.co.uk/downloads/Techpubs/Techpub-06.pdf
Many EV chargers now incorporate the required protection within the
charger, removing the need for feeding it from an external RCD.
It's not just EV's though. Houses are full of modern stuff
like PC's and LED bulbs etc. which are claimed to have the
capability of imposing DC on the AC mains.
As all my circuits are on RCBOs of Type A, I don't need to worry about that.
Joe
2024-05-20 12:52:10 UTC
Reply
Permalink
On Mon, 20 May 2024 10:21:34 +0100
Post by Andrew
It's not just EV's though. Houses are full of modern stuff
like PC's and LED bulbs etc. which are claimed to have the
capability of imposing DC on the AC mains.
And not so modern. Pretty much all TVs were once live chassis, using
half-wave rectification of the mains. Many sets were AC/DC in the early
years, so there wasn't really much choice. OK when there was only a
million or so, but eventually it became a problem.
--
Joe
Andy Burns
2024-05-20 11:23:28 UTC
Reply
Permalink
Post by SteveW
Many EV chargers now incorporate the required protection within the
charger, removing the need for feeding it from an external RCD.
And the more sophisticated ones can even disconnect the earth along with
live/neutral in the case of a PEN fault.
Andrew
2024-05-19 14:24:30 UTC
Reply
Permalink
Post by SteveW
Post by Andrew
Post by Chris Hogg
On Thu, 16 May 2024 10:53:35 +0100, The Natural Philosopher
Post by The Natural Philosopher
Id go full RCBO if money and space permitted
When this bungalow was being modernised six years ago, including
re-wiring and a new CU, I specified RCBO's on all the circuits. I have
seven: two B6's for two lighting circuits, a B16 for the immersion
heater, a B20 for the gas boiler and C/H, two B32's (sockets, kitchen
and garage, and sockets rest of the bungalow) and a B40 for the
cooker.
Oh dear. Type AC RCD's and ?RCBO's are now banned.
watch out for a sparky telling you that they are illegal and must be
replaced by type A devices (which are said to be resistant to locking
up due to DC saturating the iron core, or something like that).
If you ever get an EV then I think it will need to have its own
RCD protected feed and this will have to be a type A device.
Not necessarily.
We had an EV charger installed last year. The charger manufacturer's
normal requirement is just an isolator and a double-pole MCB in its own
enclosure, with no need for an RCD or RCBO external to the charger
itself; the cable was run inside the electricity box and then through
the wall to the back of the charger, therefore there was no wiring
regulations requirement for an RCD on that; if an external run or a
shallow internal channel was required, the installer would have used
cable with built-in mechanical protection, so again, no need for an RCD.
However, I did not want the extra enclosure, plus Henley blocks and
extra tails and preferred the cable straight into our existing CU. By
using an RCBO rather than a double-pole MCB, I obtained the required
overcurrent protection and double-pole isolation, while using only a
single slot - the RCD part of the RCBO is not actually required at all.
Post by Andrew
but I'm
not sure if all the others would need changing. Someone with knowledge
of rev 18 will be along shortly to explain.
Wiring Regulations are not retrospective - there's no need to have any
RCDs or RCBOs on an older installation. Changes to that installation may
require upgrades at the CU though.
Also some suggestion that an excess DC superimposed in the
mains could affect an neighbour, if this blog is believable

https://www.cef.co.uk/blog/2850-what-changed-with-rcds-in-amendment-2
Tim+
2024-05-19 16:16:41 UTC
Reply
Permalink
Post by SteveW
Post by Andrew
Post by Chris Hogg
On Thu, 16 May 2024 10:53:35 +0100, The Natural Philosopher
Post by The Natural Philosopher
Id go full RCBO if money and space permitted
When this bungalow was being modernised six years ago, including
re-wiring and a new CU, I specified RCBO's on all the circuits. I have
seven: two B6's for two lighting circuits, a B16 for the immersion
heater, a B20 for the gas boiler and C/H, two B32's (sockets, kitchen
and garage, and sockets rest of the bungalow) and a B40 for the
cooker.
Oh dear. Type AC RCD's and ?RCBO's are now banned.
watch out for a sparky telling you that they are illegal and must be
replaced by type A devices (which are said to be resistant to locking
up due to DC saturating the iron core, or something like that).
If you ever get an EV then I think it will need to have its own
RCD protected feed and this will have to be a type A device.
Not necessarily.
We had an EV charger installed last year. The charger manufacturer's
normal requirement is just an isolator and a double-pole MCB in its own
enclosure, with no need for an RCD or RCBO external to the charger
itself; the cable was run inside the electricity box and then through
the wall to the back of the charger, therefore there was no wiring
regulations requirement for an RCD on that; if an external run or a
shallow internal channel was required, the installer would have used
cable with built-in mechanical protection, so again, no need for an RCD.
However, I did not want the extra enclosure, plus Henley blocks and
extra tails and preferred the cable straight into our existing CU. By
using an RCBO rather than a double-pole MCB, I obtained the required
overcurrent protection and double-pole isolation, while using only a
single slot - the RCD part of the RCBO is not actually required at all.
Whilst “untidier”, having a separate enclosure and Henley blocks make it
far easier to isolate vehicle charging power from a solar
panel/battery/inverter set up.

It’s all too easy to end up draining your house battery into your car
otherwise.

Tim
--
Please don't feed the trolls
SteveW
2024-05-20 09:14:00 UTC
Reply
Permalink
Post by Tim+
Post by SteveW
Post by Andrew
Post by Chris Hogg
On Thu, 16 May 2024 10:53:35 +0100, The Natural Philosopher
Post by The Natural Philosopher
Id go full RCBO if money and space permitted
When this bungalow was being modernised six years ago, including
re-wiring and a new CU, I specified RCBO's on all the circuits. I have
seven: two B6's for two lighting circuits, a B16 for the immersion
heater, a B20 for the gas boiler and C/H, two B32's (sockets, kitchen
and garage, and sockets rest of the bungalow) and a B40 for the
cooker.
Oh dear. Type AC RCD's and ?RCBO's are now banned.
watch out for a sparky telling you that they are illegal and must be
replaced by type A devices (which are said to be resistant to locking
up due to DC saturating the iron core, or something like that).
If you ever get an EV then I think it will need to have its own
RCD protected feed and this will have to be a type A device.
Not necessarily.
We had an EV charger installed last year. The charger manufacturer's
normal requirement is just an isolator and a double-pole MCB in its own
enclosure, with no need for an RCD or RCBO external to the charger
itself; the cable was run inside the electricity box and then through
the wall to the back of the charger, therefore there was no wiring
regulations requirement for an RCD on that; if an external run or a
shallow internal channel was required, the installer would have used
cable with built-in mechanical protection, so again, no need for an RCD.
However, I did not want the extra enclosure, plus Henley blocks and
extra tails and preferred the cable straight into our existing CU. By
using an RCBO rather than a double-pole MCB, I obtained the required
overcurrent protection and double-pole isolation, while using only a
single slot - the RCD part of the RCBO is not actually required at all.
Whilst “untidier”, having a separate enclosure and Henley blocks make it
far easier to isolate vehicle charging power from a solar
panel/battery/inverter set up.
It’s all too easy to end up draining your house battery into your car
otherwise.
The separate enclosure and Henley blocks would have taken up the space
required for any future changes, such as a solar system.
charles
2024-05-20 12:08:02 UTC
Reply
Permalink
Post by SteveW
Post by SteveW
Post by Andrew
Post by Chris Hogg
On Thu, 16 May 2024 10:53:35 +0100, The Natural Philosopher
Post by The Natural Philosopher
Id go full RCBO if money and space permitted
When this bungalow was being modernised six years ago, including
re-wiring and a new CU, I specified RCBO's on all the circuits. I
have seven: two B6's for two lighting circuits, a B16 for the
immersion heater, a B20 for the gas boiler and C/H, two B32's
(sockets, kitchen and garage, and sockets rest of the bungalow) and
a B40 for the cooker.
Oh dear. Type AC RCD's and ?RCBO's are now banned.
watch out for a sparky telling you that they are illegal and must be
replaced by type A devices (which are said to be resistant to locking
up due to DC saturating the iron core, or something like that).
If you ever get an EV then I think it will need to have its own RCD
protected feed and this will have to be a type A device.
Not necessarily.
We had an EV charger installed last year. The charger manufacturer's
normal requirement is just an isolator and a double-pole MCB in its
own enclosure, with no need for an RCD or RCBO external to the charger
itself; the cable was run inside the electricity box and then through
the wall to the back of the charger, therefore there was no wiring
regulations requirement for an RCD on that; if an external run or a
shallow internal channel was required, the installer would have used
cable with built-in mechanical protection, so again, no need for an RCD.
However, I did not want the extra enclosure, plus Henley blocks and
extra tails and preferred the cable straight into our existing CU. By
using an RCBO rather than a double-pole MCB, I obtained the required
overcurrent protection and double-pole isolation, while using only a
single slot - the RCD part of the RCBO is not actually required at all.
Whilst ”untidier•, having a separate enclosure and Henley blocks make
it far easier to isolate vehicle charging power from a solar
panel/battery/inverter set up.
It‘s all too easy to end up draining your house battery into your car
otherwise.
The separate enclosure and Henley blocks would have taken up the space
required for any future changes, such as a solar system.
I had room for both. The EV supply has a C32 RCD
--
from KT24 in Surrey, England - sent from my RISC OS 4té²
"I'd rather die of exhaustion than die of boredom" Thomas Carlyle
SteveW
2024-05-20 12:14:02 UTC
Reply
Permalink
Post by charles
Post by SteveW
Post by SteveW
Post by Andrew
Post by Chris Hogg
On Thu, 16 May 2024 10:53:35 +0100, The Natural Philosopher
Post by The Natural Philosopher
Id go full RCBO if money and space permitted
When this bungalow was being modernised six years ago, including
re-wiring and a new CU, I specified RCBO's on all the circuits. I
have seven: two B6's for two lighting circuits, a B16 for the
immersion heater, a B20 for the gas boiler and C/H, two B32's
(sockets, kitchen and garage, and sockets rest of the bungalow) and
a B40 for the cooker.
Oh dear. Type AC RCD's and ?RCBO's are now banned.
watch out for a sparky telling you that they are illegal and must be
replaced by type A devices (which are said to be resistant to locking
up due to DC saturating the iron core, or something like that).
If you ever get an EV then I think it will need to have its own RCD
protected feed and this will have to be a type A device.
Not necessarily.
We had an EV charger installed last year. The charger manufacturer's
normal requirement is just an isolator and a double-pole MCB in its
own enclosure, with no need for an RCD or RCBO external to the charger
itself; the cable was run inside the electricity box and then through
the wall to the back of the charger, therefore there was no wiring
regulations requirement for an RCD on that; if an external run or a
shallow internal channel was required, the installer would have used
cable with built-in mechanical protection, so again, no need for an RCD.
However, I did not want the extra enclosure, plus Henley blocks and
extra tails and preferred the cable straight into our existing CU. By
using an RCBO rather than a double-pole MCB, I obtained the required
overcurrent protection and double-pole isolation, while using only a
single slot - the RCD part of the RCBO is not actually required at all.
Whilst ”untidier•, having a separate enclosure and Henley blocks make
it far easier to isolate vehicle charging power from a solar
panel/battery/inverter set up.
It‘s all too easy to end up draining your house battery into your car
otherwise.
The separate enclosure and Henley blocks would have taken up the space
required for any future changes, such as a solar system.
I had room for both. The EV supply has a C32 RCD
Unfortunately, out electricity cupboard is in the hallway and is quite
cramped. I can't really extend it, as it is recessed into the wall (the
wall is single skin brick where the cupboard is and cavity on the rest
of the wall). There is the front door to one side, the corner of the
house to the other, the bottom platform of the stairs below and a window
directly above. I'm stuck with the space that I've got or a complete
re-wire to another location.
Theo
2024-05-20 12:39:48 UTC
Reply
Permalink
Post by SteveW
Unfortunately, out electricity cupboard is in the hallway and is quite
cramped. I can't really extend it, as it is recessed into the wall (the
wall is single skin brick where the cupboard is and cavity on the rest
of the wall). There is the front door to one side, the corner of the
house to the other, the bottom platform of the stairs below and a window
directly above. I'm stuck with the space that I've got or a complete
re-wire to another location.
It isn't so complicated to relocate the consumer unit if you had to - there
are products like this that simplify it:

https://www.wiska.co.uk/en/30/pov/1506/818-consumer-unit-relocation-kit.html

- you basically just install that where the old CU was, push in the circuits
to one side of the Wagos, and then run new wiring off to wherever the new CU
wants to be.

About £70, so not super expensive, and it reduces the labour costs.

Theo
Andy Burns
2024-05-20 13:11:42 UTC
Reply
Permalink
Post by Theo
It isn't so complicated to relocate the consumer unit if you had to - there
https://www.wiska.co.uk/en/30/pov/1506/818-consumer-unit-relocation-kit.html
Odd that a new CU (modulo the ifs and buts) has to be metal, but that
kit is plastic.

John Rumm
2024-05-16 00:32:48 UTC
Reply
Permalink
Post by SteveW
Post by David Wade
Post by Alan Lee
Post by David Wade
Post by John Rumm
A so called "whole house" RCD - long since deprecated, but you are
certainly not alone in still having an installation like that.
So showing the stupidity of the wiring regulations which permit old
installations to remain in place even though they have long been obsolete...
Why's that then?
They havent been made obsolete, just that better ways are now available.
If it trips, its a nuisance as all power is lost, but it isnt unsafe.
Depends on your definition of "safe". If it trips in the middle of the
night you are left with no power and no light. Of course you should
have a torch but have recently had a hard trip due to water ingress on
my split board which persisted even though the MCB was off, I would
suggest this could be very very inconvenient...
In houses with a whole house RCD (except for TT systems), the lights
would not have been put under the RCD protection.
They commonly were... there was a time when adding a new enclosure
containing a RCD before the existing CU was quite a common practice.
Post by SteveW
Later, dual-RCD, installations should have had the lights on the
opposite RCD to the sockets for each floor, so tripping of the lights on
one floor would still allow a table lamp, TV or suchlike to give some light.
--
Cheers,

John.

/=================================================================\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\=================================================================/
SteveW
2024-05-16 09:11:35 UTC
Reply
Permalink
Post by John Rumm
Post by SteveW
Post by David Wade
Post by Alan Lee
Post by David Wade
Post by John Rumm
A so called "whole house" RCD - long since deprecated, but you are
certainly not alone in still having an installation like that.
So showing the stupidity of the wiring regulations which permit old
installations to remain in place even though they have long been obsolete...
Why's that then?
They havent been made obsolete, just that better ways are now available.
If it trips, its a nuisance as all power is lost, but it isnt unsafe.
Depends on your definition of "safe". If it trips in the middle of
the night you are left with no power and no light. Of course you
should have a torch but have recently had a hard trip due to water
ingress on my split board which persisted even though the MCB was
off, I would suggest this could be very very inconvenient...
In houses with a whole house RCD (except for TT systems), the lights
would not have been put under the RCD protection.
They commonly were... there was a time when adding a new enclosure
containing a RCD before the existing CU was quite a common practice.
Extra protection could be provided, but for 16th edition installations,
the norm was a consumer unit with a single RCD, required only to cover
sockets likely to be used to supply equipment outdoors - although it
often covered all sockets. The CUs were generally split-load, with
lighting on the non-RCD side. Even new installations were generally like
that.
John Rumm
2024-05-16 11:00:47 UTC
Reply
Permalink
Post by SteveW
Post by John Rumm
Post by SteveW
Post by David Wade
Post by Alan Lee
Post by David Wade
Post by John Rumm
A so called "whole house" RCD - long since deprecated, but you
are certainly not alone in still having an installation like that.
So showing the stupidity of the wiring regulations which permit
old installations to remain in place even though they have long
been obsolete...
Why's that then?
They havent been made obsolete, just that better ways are now available.
If it trips, its a nuisance as all power is lost, but it isnt unsafe.
Depends on your definition of "safe". If it trips in the middle of
the night you are left with no power and no light. Of course you
should have a torch but have recently had a hard trip due to water
ingress on my split board which persisted even though the MCB was
off, I would suggest this could be very very inconvenient...
In houses with a whole house RCD (except for TT systems), the lights
would not have been put under the RCD protection.
They commonly were... there was a time when adding a new enclosure
containing a RCD before the existing CU was quite a common practice.
Extra protection could be provided, but for 16th edition installations,
the norm was a consumer unit with a single RCD, required only to cover
sockets likely to be used to supply equipment outdoors - although it
often covered all sockets. The CUs were generally split-load, with
lighting on the non-RCD side. Even new installations were generally like
that.
You are right, a typical 16th edition "split load" CU would have one RCD
protecting some or all of the socket circuits, and typically anything
else not on the protected side. These are not what most would understand
as a "whole house" RCD install though.

IME many of the "converted" whole house RCD installs are pre 16th
edition (quite often long before 16th edition!). Often Wylex a BS 3036
re-wireable fuse boards, where they were upgraded with a front end RCD
to feed the whole CU.
--
Cheers,

John.

/=================================================================\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\=================================================================/
charles
2024-05-16 16:15:02 UTC
Reply
Permalink
Post by John Rumm
Post by SteveW
Post by John Rumm
Post by SteveW
Post by David Wade
Post by David Wade
Post by John Rumm
A so called "whole house" RCD - long since deprecated, but you
are certainly not alone in still having an installation like that.
So showing the stupidity of the wiring regulations which permit
old installations to remain in place even though they have long
been obsolete...
Why's that then? They havent been made obsolete, just that better
ways are now available. If it trips, its a nuisance as all power
is lost, but it isnt unsafe.
Depends on your definition of "safe". If it trips in the middle of
the night you are left with no power and no light. Of course you
should have a torch but have recently had a hard trip due to water
ingress on my split board which persisted even though the MCB was
off, I would suggest this could be very very inconvenient...
In houses with a whole house RCD (except for TT systems), the lights
would not have been put under the RCD protection.
They commonly were... there was a time when adding a new enclosure
containing a RCD before the existing CU was quite a common practice.
Extra protection could be provided, but for 16th edition installations,
the norm was a consumer unit with a single RCD, required only to cover
sockets likely to be used to supply equipment outdoors - although it
often covered all sockets. The CUs were generally split-load, with
lighting on the non-RCD side. Even new installations were generally
like that.
You are right, a typical 16th edition "split load" CU would have one RCD
protecting some or all of the socket circuits, and typically anything
else not on the protected side. These are not what most would understand
as a "whole house" RCD install though.
IME many of the "converted" whole house RCD installs are pre 16th
edition (quite often long before 16th edition!). Often Wylex a BS 3036
re-wireable fuse boards, where they were upgraded with a front end RCD
to feed the whole CU.
My workshop had a Wylex fuse board - I changed the fuses for MCBs.

I've still got my copy of the 15th Edition, perhaps I should re-read it.
--
from KT24 in Surrey, England - sent from my RISC OS 4té²
"I'd rather die of exhaustion than die of boredom" Thomas Carlyle
Theo
2024-05-16 21:23:52 UTC
Reply
Permalink
Post by charles
I've still got my copy of the 15th Edition, perhaps I should re-read it.
If you want to be up to date:
https://www.scribd.com/document/568048110/BS7671-2018-Amd-2

Various websites will download from Scribd without logging in, eg
https://scribd.downloader.tips/document/568048110/BS7671-2018-Amd-2

Theo
Andrew
2024-05-19 13:56:16 UTC
Reply
Permalink
Post by John Rumm
Post by SteveW
Post by John Rumm
Post by SteveW
Post by David Wade
Post by Alan Lee
Post by David Wade
Post by John Rumm
A so called "whole house" RCD - long since deprecated, but you
are certainly not alone in still having an installation like that.
So showing the stupidity of the wiring regulations which permit
old installations to remain in place even though they have long
been obsolete...
Why's that then?
They havent been made obsolete, just that better ways are now available.
If it trips, its a nuisance as all power is lost, but it isnt unsafe.
Depends on your definition of "safe". If it trips in the middle of
the night you are left with no power and no light. Of course you
should have a torch but have recently had a hard trip due to water
ingress on my split board which persisted even though the MCB was
off, I would suggest this could be very very inconvenient...
In houses with a whole house RCD (except for TT systems), the lights
would not have been put under the RCD protection.
They commonly were... there was a time when adding a new enclosure
containing a RCD before the existing CU was quite a common practice.
Extra protection could be provided, but for 16th edition
installations, the norm was a consumer unit with a single RCD,
required only to cover sockets likely to be used to supply equipment
outdoors - although it often covered all sockets. The CUs were
generally split-load, with lighting on the non-RCD side. Even new
installations were generally like that.
You are right, a typical 16th edition "split load" CU would have one RCD
protecting some or all of the socket circuits, and typically anything
else not on the protected side. These are not what most would understand
as a "whole house" RCD install though.
IME many of the "converted" whole house RCD installs are pre 16th
edition (quite often long before 16th edition!). Often Wylex a BS 3036
re-wireable fuse boards, where they were upgraded with a front end RCD
to feed the whole CU.
Parents 1956-built house (no cpc in lighting circuits) was
upgraded like this).
The Natural Philosopher
2024-05-15 19:51:45 UTC
Reply
Permalink
Post by David Wade
Post by John Rumm
Post by Smolley
I have a 30ma 'trip' on the Consumer Unit main switch.
A so called "whole house" RCD - long since deprecated, but you are
certainly not alone in still having an installation like that.
So showing the stupidity of the wiring regulations which permit old
installations to remain in place even though they have long been obsolete...
Nothing wrong with whole house RCD - better than no RCD.

Obviously the bastards trip too often and RCBOs are better.
Post by David Wade
Dave
--
Microsoft : the best reason to go to Linux that ever existed.
John Rumm
2024-05-16 00:30:25 UTC
Reply
Permalink
Post by David Wade
Post by John Rumm
Post by Smolley
I have a 30ma 'trip' on the Consumer Unit main switch.
A so called "whole house" RCD - long since deprecated, but you are
certainly not alone in still having an installation like that.
So showing the stupidity of the wiring regulations which permit old
installations to remain in place even though they have long been obsolete...
What would be the alternative?

Can you imagine the outcry if every time a new revision of the wiring
regs (or a new amendment to the current one) was released, every
property owner was supposed to bring their properties up to the new
standard?

The current scheme for requiring new work to be done to current
standards is a much more workable policy, and with time achieves much
the same result.
--
Cheers,

John.

/=================================================================\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\=================================================================/
David Wade
2024-05-16 09:40:41 UTC
Reply
Permalink
Post by John Rumm
Post by David Wade
Post by John Rumm
Post by Smolley
I have a 30ma 'trip' on the Consumer Unit main switch.
A so called "whole house" RCD - long since deprecated, but you are
certainly not alone in still having an installation like that.
So showing the stupidity of the wiring regulations which permit old
installations to remain in place even though they have long been obsolete...
What would be the alternative?
Can you imagine the outcry if every time a new revision of the wiring
regs (or a new amendment to the current one) was released, every
property owner was supposed to bring their properties up to the new
standard?
The current scheme for requiring new work to be done to current
standards is a much more workable policy, and with time achieves much
the same result.
In time yes, but possibly killing several people on the way.themselves
on the way. Having watch two friends with mild dementia attempt recently
attempt to electrocute themselves, on different occasions and in
different ways, which was possible because they still had systems with
no RCD and conventional fuses.

My next door neighbour attempted to clean a plugged in hair dryer with a
nail file. Not sure how she escaped electrocution, perhaps she shorted
live to earth or neutral and it took the fuse out, but she was shaking
and admitted she had had a nasty belt.

Another put a 13am plug rotated 180 degrees and was then about to poke
things into the now open slots when I stopped him....

The current policy and part-P both discourage upgrades. Many people
don't upgrade because you either stay on the old system, or you move to
the latest level. There is no in-between. In both the above cases the
people were elderly and stuck with their old systems because they didn't
want the disruption a proper upgrade would cause.

Part-P again discourages upgrades because it then becomes notifiable and
folks don't want the hassle of that....



Dave
Andrew
2024-05-16 10:19:09 UTC
Reply
Permalink
Post by David Wade
Post by John Rumm
Post by David Wade
Post by John Rumm
Post by Smolley
I have a 30ma 'trip' on the Consumer Unit main switch.
A so called "whole house" RCD - long since deprecated, but you are
certainly not alone in still having an installation like that.
So showing the stupidity of the wiring regulations which permit old
installations to remain in place even though they have long been obsolete...
What would be the alternative?
Can you imagine the outcry if every time a new revision of the wiring
regs (or a new amendment to the current one) was released, every
property owner was supposed to bring their properties up to the new
standard?
The current scheme for requiring new work to be done to current
standards is a much more workable policy, and with time achieves much
the same result.
In time yes, but possibly killing several people on the way.themselves
on the way. Having watch two friends with mild dementia attempt recently
attempt to electrocute themselves, on different occasions and in
different ways, which was possible  because they still had systems with
no RCD and conventional fuses.
So what ?. There are plenty of other ways that they will find to
kill or hurt themselves.
Post by David Wade
My next door neighbour attempted to clean a plugged in hair dryer with a
nail file. Not sure how she escaped electrocution, perhaps she shorted
live to earth or neutral and it took the fuse out, but she was shaking
and admitted she had had a nasty belt.
Darwinism.
Post by David Wade
Another put a 13am plug rotated 180 degrees and was then about to poke
things into the now open slots when I stopped him....
Not possible with flush mounted socket outlets
Post by David Wade
The current policy and part-P both discourage upgrades. Many people
don't upgrade because you either stay on the old system, or you move to
the latest level. There is no in-between. In both the above cases the
people were elderly and stuck with their old systems because they didn't
want the disruption a proper upgrade would cause.
Part-P again discourages upgrades because it then becomes notifiable and
folks don't want the hassle of that....
Dave
SteveW
2024-05-16 14:37:52 UTC
Reply
Permalink
Post by David Wade
Post by John Rumm
Post by David Wade
Post by John Rumm
Post by Smolley
I have a 30ma 'trip' on the Consumer Unit main switch.
A so called "whole house" RCD - long since deprecated, but you are
certainly not alone in still having an installation like that.
So showing the stupidity of the wiring regulations which permit old
installations to remain in place even though they have long been obsolete...
What would be the alternative?
Can you imagine the outcry if every time a new revision of the wiring
regs (or a new amendment to the current one) was released, every
property owner was supposed to bring their properties up to the new
standard?
The current scheme for requiring new work to be done to current
standards is a much more workable policy, and with time achieves much
the same result.
In time yes, but possibly killing several people on the way.themselves
on the way.
The alternative is spending huge amounts of money, with lots of
disruption, disproportionate to the number of lives saved.

<SNIP>
Post by David Wade
The current policy and part-P both discourage upgrades. Many people
don't upgrade because you either stay on the old system, or you move to
the latest level. There is no in-between. In both the above cases the
people were elderly and stuck with their old systems because they didn't
want the disruption a proper upgrade would cause.
Part-P again discourages upgrades because it then becomes notifiable and
folks don't want the hassle of that....
Yes, Part P simply causes bodges - such as my conservatory electrics
being an extension of the existing ring, with an FCU for the lighting
... when I have spare ways in the CU and a direct, underfloor route for
cabling.
Fredxx
2024-05-16 21:36:44 UTC
Reply
Permalink
Post by David Wade
Post by John Rumm
Post by David Wade
Post by John Rumm
Post by Smolley
I have a 30ma 'trip' on the Consumer Unit main switch.
A so called "whole house" RCD - long since deprecated, but you are
certainly not alone in still having an installation like that.
So showing the stupidity of the wiring regulations which permit old
installations to remain in place even though they have long been obsolete...
What would be the alternative?
Can you imagine the outcry if every time a new revision of the wiring
regs (or a new amendment to the current one) was released, every
property owner was supposed to bring their properties up to the new
standard?
The current scheme for requiring new work to be done to current
standards is a much more workable policy, and with time achieves much
the same result.
In time yes, but possibly killing several people on the way.themselves
on the way. Having watch two friends with mild dementia attempt recently
attempt to electrocute themselves, on different occasions and in
different ways, which was possible  because they still had systems with
no RCD and conventional fuses.
My next door neighbour attempted to clean a plugged in hair dryer with a
nail file. Not sure how she escaped electrocution, perhaps she shorted
live to earth or neutral and it took the fuse out, but she was shaking
and admitted she had had a nasty belt.
Why do you think an RCD would save the day? All the hair driers I've
seen are double insulated with no visible earth.
Post by David Wade
Another put a 13am plug rotated 180 degrees and was then about to poke
things into the now open slots when I stopped him....
We're now getting into the stage where all sockets should be replaced
with fused outlets.
Post by David Wade
The current policy and part-P both discourage upgrades.
Now that I agree with you.
Theo
2024-05-16 21:50:12 UTC
Reply
Permalink
Post by Fredxx
Post by David Wade
My next door neighbour attempted to clean a plugged in hair dryer with a
nail file. Not sure how she escaped electrocution, perhaps she shorted
live to earth or neutral and it took the fuse out, but she was shaking
and admitted she had had a nasty belt.
Why do you think an RCD would save the day? All the hair driers I've
seen are double insulated with no visible earth.
Presumably a current flowing from the exposed live heating element through
the nail file and the lady to earth would trip the RCD?

Without an RCD it would require enough live-side current to blow the fuse or
trip the MCB, which is a lot less than a 30mA RCD earth fault. Perhaps
shorting element windings would do it, whereas leakage from the live
conductor might trip before the file had been inserted far enough to short
anything.

Theo
Fredxx
2024-05-16 23:45:26 UTC
Reply
Permalink
Post by Theo
Post by Fredxx
Post by David Wade
My next door neighbour attempted to clean a plugged in hair dryer with a
nail file. Not sure how she escaped electrocution, perhaps she shorted
live to earth or neutral and it took the fuse out, but she was shaking
and admitted she had had a nasty belt.
Why do you think an RCD would save the day? All the hair driers I've
seen are double insulated with no visible earth.
Presumably a current flowing from the exposed live heating element through
the nail file and the lady to earth would trip the RCD?
Without an RCD it would require enough live-side current to blow the fuse or
trip the MCB, which is a lot less than a 30mA RCD earth fault. Perhaps
shorting element windings would do it, whereas leakage from the live
conductor might trip before the file had been inserted far enough to short
anything.
We are told that a fuse had blown. And that it was a 'nasty belt'.

https://en.wikipedia.org/wiki/Electrical_injury

The let go threshold is around 10mA. A 30mA RCD should not trip unless
over 15mA and below 30mA.

I would also wager that the lady was on an insulating surface such that
the current to ground could have been well below 30mA and likely below 15mA.

I would say that the only advantage of a more modern system would have
been a faster reacting MCB. Either way the likelihood of a "shorted
live to earth" in a double insulated hair drier is remote.
David Wade
2024-05-17 09:42:28 UTC
Reply
Permalink
Post by Fredxx
Post by Theo
Post by Fredxx
Post by David Wade
My next door neighbour attempted to clean a plugged in hair dryer with a
nail file. Not sure how she escaped electrocution, perhaps she shorted
live to earth or neutral and it took the fuse out, but she was shaking
and admitted she had had a nasty belt.
Why do you think an RCD would save the day? All the hair driers I've
seen are double insulated with no visible earth.
Presumably a current flowing from the exposed live heating element through
the nail file and the lady to earth would trip the RCD?
Without an RCD it would require enough live-side current to blow the fuse or
trip the MCB, which is a lot less than a 30mA RCD earth fault.  Perhaps
shorting element windings would do it, whereas leakage from the live
conductor might trip before the file had been inserted far enough to short
anything.
We are told that a fuse had blown. And that it was a 'nasty belt'.
https://en.wikipedia.org/wiki/Electrical_injury
The let go threshold is around 10mA. A 30mA RCD should not trip unless
over 15mA and below 30mA.
I would also wager that the lady was on an insulating surface such that
the current to ground could have been well below 30mA and likely below 15mA.
I would say that the only advantage of a more modern system would have
been a faster reacting MCB. Either way the likelihood of a "shorted
live to earth" in a double insulated hair drier is remote.
I wondered about that. I should have examined the dryer more closely.
She admitted trying to clean it with a nail file .....

Dave
David Wade
2024-05-17 09:40:09 UTC
Reply
Permalink
Post by Fredxx
Post by David Wade
Post by John Rumm
Post by David Wade
Post by John Rumm
Post by Smolley
I have a 30ma 'trip' on the Consumer Unit main switch.
A so called "whole house" RCD - long since deprecated, but you are
certainly not alone in still having an installation like that.
So showing the stupidity of the wiring regulations which permit old
installations to remain in place even though they have long been obsolete...
What would be the alternative?
Can you imagine the outcry if every time a new revision of the wiring
regs (or a new amendment to the current one) was released, every
property owner was supposed to bring their properties up to the new
standard?
The current scheme for requiring new work to be done to current
standards is a much more workable policy, and with time achieves much
the same result.
In time yes, but possibly killing several people on the way.themselves
on the way. Having watch two friends with mild dementia attempt
recently attempt to electrocute themselves, on different occasions and
in different ways, which was possible  because they still had systems
with no RCD and conventional fuses.
My next door neighbour attempted to clean a plugged in hair dryer with
a nail file. Not sure how she escaped electrocution, perhaps she
shorted live to earth or neutral and it took the fuse out, but she was
shaking and admitted she had had a nasty belt.
Why do you think an RCD would save the day? All the hair driers I've
seen are double insulated with no visible earth.
Do hair dryers really count as double insulated? Whatever she did took
the fuse out.
Post by Fredxx
Post by David Wade
Another put a 13am plug rotated 180 degrees and was then about to poke
things into the now open slots when I stopped him....
We're now getting into the stage where all sockets should be replaced
with fused outlets.
So you are implying a re-wire? Really extension bars should not get
approval for sale if the distance from the earth pin to the closest side
is less than the gap between the earth and live/neutral pins as this
allows a plug to be inserted in a way which opens the shutters...
Post by Fredxx
Post by David Wade
The current policy and part-P both discourage upgrades.
Now that I agree with you.
alan_m
2024-05-19 16:23:57 UTC
Reply
Permalink
Post by David Wade
Post by John Rumm
Post by Smolley
I have a 30ma 'trip' on the Consumer Unit main switch.
A so called "whole house" RCD - long since deprecated, but you are
certainly not alone in still having an installation like that.
So showing the stupidity of the wiring regulations which permit old
installations to remain in place even though they have long been obsolete...
Yep, every time the regulations change 30 million houses would have to
be upgraded. How many times have you had your consumer unit upgraded in
the past few years because of changes to the regulations?
--
mailto : news {at} admac {dot} myzen {dot} co {dot} uk
Vir Campestris
2024-05-19 19:50:27 UTC
Reply
Permalink
Post by alan_m
Yep, every time the regulations change 30 million houses would have to
be upgraded. How many times have you had your consumer unit upgraded in
the past few years because of changes to the regulations?
When we bought our house the surveyor said the wiring was in urgent need
of attention. This turned out to be because there was rubber insulated
wiring running through the thatch! Only 10 years ago.

But that isn't illegal. (just unwise, and I'm surprised it was insurable)

It would be illegal to install it, but not to keep using it.

Andy
Andrew
2024-05-20 08:12:31 UTC
Reply
Permalink
Post by Vir Campestris
Post by alan_m
Yep, every time the regulations change 30 million houses would have to
be upgraded. How many times have you had your consumer unit upgraded
in the past few years because of changes to the regulations?
When we bought our house the surveyor said the wiring was in urgent need
of attention. This turned out to be because there was rubber insulated
wiring running through the thatch! Only 10 years ago.
But that isn't illegal. (just unwise, and I'm surprised it was insurable)
It would be illegal to install it, but not to keep using it.
Andy
Only a few metres then ?, that's nothing to what was heaved out of
Buck Palace, although the video shows cable that differs from the
pure rubber insulated wiring that was in my grandparents house up
to the the late 1970's, which literally turned to dust behind every
lightswitch.

https://www.royal.uk/rewiring-buckingham-palace-0?page=11

For Brian (in or out of bed??), it's a video taken inside
the palace. The sparkies aren't wearing full morning dress
though, pity.
David Wade
2024-05-20 08:23:53 UTC
Reply
Permalink
Post by alan_m
Post by David Wade
Post by John Rumm
Post by Smolley
I have a 30ma 'trip' on the Consumer Unit main switch.
A so called "whole house" RCD - long since deprecated, but you are
certainly not alone in still having an installation like that.
So showing the stupidity of the wiring regulations which permit old
installations to remain in place even though they have long been obsolete...
Yep, every time the regulations change 30 million houses would have to
be upgraded. How many times have you had your consumer unit upgraded in
the past few years because of changes to the regulations?
Then updating the regulations is pointless. I know of several houses
with no RCD and wire fuses...
... if the regulations truly make things safer then there should be some
push to get people to update after a major change.

Dave
Andrew
2024-05-20 08:31:43 UTC
Reply
Permalink
Post by David Wade
Post by alan_m
Post by David Wade
Post by John Rumm
Post by Smolley
I have a 30ma 'trip' on the Consumer Unit main switch.
A so called "whole house" RCD - long since deprecated, but you are
certainly not alone in still having an installation like that.
So showing the stupidity of the wiring regulations which permit old
installations to remain in place even though they have long been obsolete...
Yep, every time the regulations change 30 million houses would have to
be upgraded. How many times have you had your consumer unit upgraded
in the past few years because of changes to the regulations?
Then updating the regulations is pointless. I know of several houses
with no RCD and wire fuses...
... if the regulations truly make things safer then there should be some
push to get people to update after a major change.
Dave
Try telling the occupants (probably elderly) that they *must* spend
up to £4,000 (or more) having their entire property ripped apart
just to make it 'safe'. Then the replastering, redecorating, etc
is on top of that.

Not going to happen.

Of course the regulations have a valid point. All new builds and
extensions plus other electrical changes require adherence to the
new standards. Nothing to stop these people downsizing to a nice
modern, thermally efficient apartment with a lift.
Andy Burns
2024-05-20 08:50:54 UTC
Reply
Permalink
updating the regulations is pointless. I know of several houses with no
RCD and wire fuses...
My parents' house is one such, it hasn't burned down, I presume when the
buyer moves in they will at least have a new CU fitted ... they may
decide they need more than the two sockets per most rooms.
Max Demian
2024-05-15 16:46:17 UTC
Reply
Permalink
Post by John Rumm
Post by Smolley
I have a 30ma 'trip' on the Consumer Unit main switch.
A so called "whole house" RCD - long since deprecated, but you are
certainly not alone in still having an installation like that.
How many RCDs should one have, and what should they control?

(I have one for the cooker circuit and the gas boiler, and one for
everything else.)
--
Max Demian
David Wade
2024-05-15 17:39:20 UTC
Reply
Permalink
Post by Max Demian
Post by John Rumm
Post by Smolley
I have a 30ma 'trip' on the Consumer Unit main switch.
A so called "whole house" RCD - long since deprecated, but you are
certainly not alone in still having an installation like that.
How many RCDs should one have, and what should they control?
(I have one for the cooker circuit and the gas boiler, and one for
everything else.)
I would say latest best practice is to have no RCDs, but instead to have
one RCBO, so a combined RCD and MCB, per circuit. That way any tripping
only affects a small part of the system .

Dave
The Natural Philosopher
2024-05-15 19:55:54 UTC
Reply
Permalink
Post by David Wade
Post by Max Demian
Post by John Rumm
Post by Smolley
I have a 30ma 'trip' on the Consumer Unit main switch.
A so called "whole house" RCD - long since deprecated, but you are
certainly not alone in still having an installation like that.
How many RCDs should one have, and what should they control?
(I have one for the cooker circuit and the gas boiler, and one for
everything else.)
I would say latest best practice is to have no RCDs, but instead to have
one RCBO, so a combined RCD and MCB, per circuit. That way any tripping
only affects a small part of the system .
In an ideal world yes.
Post by David Wade
Dave
--
Climate Change: Socialism wearing a lab coat.
SteveW
2024-05-16 09:19:13 UTC
Reply
Permalink
Post by The Natural Philosopher
Post by David Wade
Post by Max Demian
Post by John Rumm
Post by Smolley
I have a 30ma 'trip' on the Consumer Unit main switch.
A so called "whole house" RCD - long since deprecated, but you are
certainly not alone in still having an installation like that.
How many RCDs should one have, and what should they control?
(I have one for the cooker circuit and the gas boiler, and one for
everything else.)
I would say latest best practice is to have no RCDs, but instead to
have one RCBO, so a combined RCD and MCB, per circuit. That way any
tripping only affects a small part of the system .
In an ideal world yes.
I have gone that route, but only after a) Crabtree introduced miniature
RCBOs that are exactly the same dimensions as their MCBs (previously
they were the same width, but much taller and my box would not fit the
old ones) and b) the price dropped to a sensible level.

I had to change the busbar to a non-split load one. The extra space from
ditching the RCD allowed me to add an SPD and added a couple of spare
spaces for future use (one now used for an EV charger).

It has solved the random trips that were due to too much leakage from
numerous filters on devices around the house.
Max Demian
2024-05-16 11:17:21 UTC
Reply
Permalink
Post by David Wade
Post by Max Demian
Post by John Rumm
Post by Smolley
I have a 30ma 'trip' on the Consumer Unit main switch.
A so called "whole house" RCD - long since deprecated, but you are
certainly not alone in still having an installation like that.
How many RCDs should one have, and what should they control?
(I have one for the cooker circuit and the gas boiler, and one for
everything else.)
I would say latest best practice is to have no RCDs, but instead to have
one RCBO, so a combined RCD and MCB, per circuit. That way any tripping
only affects a small part of the system .
If an RCBO trips, does it tell you whether it's due to a leakage current
or an overload?
--
Max Demian
Theo
2024-05-16 11:22:50 UTC
Reply
Permalink
Post by Max Demian
If an RCBO trips, does it tell you whether it's due to a leakage current
or an overload?
There is often a window which shows a different colour if there's been an
earth fault. eg the part marked (6) on this one turns blue:
https://library.e.abb.com/public/a98d6db97b0e47ee8cdb776c6bc006d7/DS301-online-data-sheet-LR.pdf

Theo
The Natural Philosopher
2024-05-15 19:55:23 UTC
Reply
Permalink
Post by Max Demian
Post by John Rumm
Post by Smolley
I have a 30ma 'trip' on the Consumer Unit main switch.
A so called "whole house" RCD - long since deprecated, but you are
certainly not alone in still having an installation like that.
How many RCDs should one have, and what should they control?
(I have one for the cooker circuit and the gas boiler, and one for
everything else.)
Its a matter of choice. Certainly modern practice is one for every
outside socket.
Personally if they fitted the CU and I had the time and the money it
would be one per ring or spur for me.
--
Microsoft : the best reason to go to Linux that ever existed.
John Rumm
2024-05-16 00:43:07 UTC
Reply
Permalink
Post by Max Demian
Post by John Rumm
Post by Smolley
I have a 30ma 'trip' on the Consumer Unit main switch.
A so called "whole house" RCD - long since deprecated, but you are
certainly not alone in still having an installation like that.
How many RCDs should one have, and what should they control?
For 17th edition installs on, the minimum would be two - with all
circuits spread between them.

However the price of RCBOs has come down dramatically, so it is entirely
reasonable to using one on most circuits, and largely do away with
"shared" RCDs.
Post by Max Demian
(I have one for the cooker circuit and the gas boiler, and one for
everything else.)
Some division on the "everything else" would probably be sensible - so
lights and sockets on one floor are powered from different RCDs. That
way you always have the option of light on each floor (even if it has to
be via a plug in lamp)
--
Cheers,

John.

/=================================================================\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\=================================================================/
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