Hall of shame

[Scott]

It looks like I am in the hall of shame. To change a lightswitch, I
switched off the downstairs RCBO forgetting that the switch at the
bottom of the stairs was connected to a light fed from the upstairs
circuit. I touched one of the conductor wires and got a shock, nothing
more than a mild tingle. Is the RCBO able to prevent a significant
electric shock? I will *not* be recommending or repeating this.

[Jeff Gaines]

Post by Scott
It looks like I am in the hall of shame. To change a lightswitch, I
switched off the downstairs RCBO forgetting that the switch at the
bottom of the stairs was connected to a light fed from the upstairs
circuit. I touched one of the conductor wires and got a shock, nothing
more than a mild tingle. Is the RCBO able to prevent a significant
electric shock? I will not be recommending or repeating this.

I have been in this property for three years now and only recently
discovered that the downstairs study/dining room is connected to the
upstairs ring while all the other rooms are on the downstairs circuit.

[Tricky Dicky]

Post by Jeff Gaines

Post by Scott
It looks like I am in the hall of shame. To change a lightswitch, I
switched off the downstairs RCBO forgetting that the switch at the
bottom of the stairs was connected to a light fed from the upstairs
circuit. I touched one of the conductor wires and got a shock, nothing
more than a mild tingle. Is the RCBO able to prevent a significant
electric shock? I will not be recommending or repeating this.

I have been in this property for three years now and only recently
discovered that the downstairs study/dining room is connected to the
upstairs ring while all the other rooms are on the downstairs circuit.

I tend to find extensions are often wired in peculiar ways. Our
conservatory lighting is wired off the main ring main which was extended
into the conservatory, at least there they used a FSU for the lights but
left a 13A fuse in which I replaced with a 5A. Our last house which had a
kitchen extension also had some peculiar wiring which was in keeping with
the total mess the rest of the house was in when we moved in.

[Andrew]

Post by Tricky Dicky

Post by Jeff Gaines

Post by Scott
It looks like I am in the hall of shame. To change a lightswitch, I
switched off the downstairs RCBO forgetting that the switch at the
bottom of the stairs was connected to a light fed from the upstairs
circuit. I touched one of the conductor wires and got a shock, nothing
more than a mild tingle. Is the RCBO able to prevent a significant
electric shock? I will not be recommending or repeating this.

I have been in this property for three years now and only recently
discovered that the downstairs study/dining room is connected to the
upstairs ring while all the other rooms are on the downstairs circuit.

I tend to find extensions are often wired in peculiar ways. Our
conservatory lighting is wired off the main ring main which was extended
into the conservatory, at least there they used a FSU for the lights but
left a 13A fuse in which I replaced with a 5A. Our last house which had a
kitchen extension also had some peculiar wiring which was in keeping with
the total mess the rest of the house was in when we moved in.

I was in B&Q on Saturday and noticed they still had loads of
packs of rewireable fuse wires plus boxes of 3,5 and 13 amp
cartridge fuses but none for 10 amps. Has this rating gone
out of favour ?.

Also noticed that they are selling MK double switched sockets
with 'wago' connectors on the back. £6.50 each though and they
looked rather bulky. I don't think you could retrofit them into
a 25mm backbox.

I have added a double socket downstairs next to the BT master
socket where the builder never put a power socket. I fed it
from the upstairs ring but via a fusible spur. The cable is
fixed to the surface of the wall which is then covered with
80mm of celotex which means that it should not be rated at
30A with the ring hence the fused spur with a 10A fuse.

[Joe]

On Tue, 18 Feb 2025 15:21:36 +0000

Post by Andrew
I have added a double socket downstairs next to the BT master
socket where the builder never put a power socket. I fed it
from the upstairs ring but via a fusible spur. The cable is
fixed to the surface of the wall which is then covered with
80mm of celotex which means that it should not be rated at
30A with the ring hence the fused spur with a 10A fuse.

From what I remember, 2.5mm T&E is rated at 23A in conduit, I think it
is about 18A fully enclosed e.g. in insulation or thin plaster.

The ring is only rated at 30/32A as there are two paths anywhere, it's
still 23A cable.

[Andrew]

Post by Joe
On Tue, 18 Feb 2025 15:21:36 +0000

Post by Andrew
I have added a double socket downstairs next to the BT master
socket where the builder never put a power socket. I fed it
from the upstairs ring but via a fusible spur. The cable is
fixed to the surface of the wall which is then covered with
80mm of celotex which means that it should not be rated at
30A with the ring hence the fused spur with a 10A fuse.

From what I remember, 2.5mm T&E is rated at 23A in conduit, I think it
is about 18A fully enclosed e.g. in insulation or thin plaster.
The ring is only rated at 30/32A as there are two paths anywhere, it's
still 23A cable.

Ok, thanks for that. I only added it to power an ONT, router, DECT
phone or similar but the next owner might plug two fan heaters into
it so its an arse-covering exercise hebce rating it at 10 amps (Red and
Black cable, I did it before Part P guv, honest).

[Scott]

Post by Jeff Gaines

Post by Scott
It looks like I am in the hall of shame. To change a lightswitch, I
switched off the downstairs RCBO forgetting that the switch at the
bottom of the stairs was connected to a light fed from the upstairs
circuit. I touched one of the conductor wires and got a shock, nothing
more than a mild tingle. Is the RCBO able to prevent a significant
electric shock? I will not be recommending or repeating this.

I have been in this property for three years now and only recently
discovered that the downstairs study/dining room is connected to the
upstairs ring while all the other rooms are on the downstairs circuit.

As someone on the group to which I posted by mistake commented,
turning off the main switch is probably best practice (even if it does
mean resetting clocks afterwards).

[Joe]

On Tue, 18 Feb 2025 13:42:20 +0000

Post by Scott

On 18/02/2025 in message

Post by Scott
It looks like I am in the hall of shame. To change a lightswitch, I
switched off the downstairs RCBO forgetting that the switch at the
bottom of the stairs was connected to a light fed from the upstairs
circuit. I touched one of the conductor wires and got a shock,
nothing more than a mild tingle. Is the RCBO able to prevent a
significant electric shock? I will not be recommending or repeating
this.

I have been in this property for three years now and only recently
discovered that the downstairs study/dining room is connected to the
upstairs ring while all the other rooms are on the downstairs
circuit.

As someone on the group to which I posted by mistake commented,
turning off the main switch is probably best practice (even if it does
mean resetting clocks afterwards).

Whatever kind of circuit you're going to work on, turn something on,
ideally the light or socket you'll be touching. Pull the fuse/breaker
and go straight back to confirm what you turned on is now dead.
Sometimes you will be surprised.

In the old days, you could carry the fuse in your pocket to ensure
nobody else plugged it back in, and the early circuit breakers plugged
into the same fuseholders for compatibility, and could also be removed.

I'd have thought that with a leakage detection breaker, you shouldn't
feel anything. I sometimes worked on an oscilloscope that had the
(unshielded) mains fuse sitting on top of the chassis at the rear.
Occasionally the workshop radio would go off, and I'd look up to see
who had turned it off, finding that it had been me. Never felt a thing.

[Scott]

Post by Joe
On Tue, 18 Feb 2025 13:42:20 +0000

Post by Scott

On 18/02/2025 in message

Post by Scott
It looks like I am in the hall of shame. To change a lightswitch, I
switched off the downstairs RCBO forgetting that the switch at the
bottom of the stairs was connected to a light fed from the upstairs
circuit. I touched one of the conductor wires and got a shock,
nothing more than a mild tingle. Is the RCBO able to prevent a
significant electric shock? I will not be recommending or repeating
this.

I have been in this property for three years now and only recently
discovered that the downstairs study/dining room is connected to the
upstairs ring while all the other rooms are on the downstairs circuit.

As someone on the group to which I posted by mistake commented,
turning off the main switch is probably best practice (even if it does
mean resetting clocks afterwards).

Whatever kind of circuit you're going to work on, turn something on,
ideally the light or socket you'll be touching. Pull the fuse/breaker
and go straight back to confirm what you turned on is now dead.
Sometimes you will be surprised.
In the old days, you could carry the fuse in your pocket to ensure
nobody else plugged it back in, and the early circuit breakers plugged
into the same fuseholders for compatibility, and could also be removed.
I'd have thought that with a leakage detection breaker, you shouldn't
feel anything. I sometimes worked on an oscilloscope that had the
(unshielded) mains fuse sitting on top of the chassis at the rear.
Occasionally the workshop radio would go off, and I'd look up to see
who had turned it off, finding that it had been me. Never felt a thing.

As the saying goes, I couldn't agree more (hence the subject line).

[John R Walliker]

Post by Joe
On Tue, 18 Feb 2025 13:42:20 +0000

Post by Scott

On 18/02/2025 in message

Post by Scott
It looks like I am in the hall of shame. To change a lightswitch, I
switched off the downstairs RCBO forgetting that the switch at the
bottom of the stairs was connected to a light fed from the upstairs
circuit. I touched one of the conductor wires and got a shock,
nothing more than a mild tingle. Is the RCBO able to prevent a
significant electric shock? I will not be recommending or repeating
this.

I have been in this property for three years now and only recently
discovered that the downstairs study/dining room is connected to the
upstairs ring while all the other rooms are on the downstairs circuit.

As someone on the group to which I posted by mistake commented,
turning off the main switch is probably best practice (even if it does
mean resetting clocks afterwards).

Whatever kind of circuit you're going to work on, turn something on,
ideally the light or socket you'll be touching. Pull the fuse/breaker
and go straight back to confirm what you turned on is now dead.
Sometimes you will be surprised.
In the old days, you could carry the fuse in your pocket to ensure
nobody else plugged it back in, and the early circuit breakers plugged
into the same fuseholders for compatibility, and could also be removed.
I'd have thought that with a leakage detection breaker, you shouldn't
feel anything.

Unfortunately, they don't work that way. They do not limit the current
that can flow through your body at all. They just limit how long it
lasts for.
John

Post by Joe
I sometimes worked on an oscilloscope that had the
(unshielded) mains fuse sitting on top of the chassis at the rear.
Occasionally the workshop radio would go off, and I'd look up to see
who had turned it off, finding that it had been me. Never felt a thing.

[SteveW]

Post by Joe
On Tue, 18 Feb 2025 13:42:20 +0000

Post by Scott

On 18/02/2025 in message

Post by Scott
It looks like I am in the hall of shame. To change a lightswitch, I
switched off the downstairs RCBO forgetting that the switch at the
bottom of the stairs was connected to a light fed from the upstairs
circuit. I touched one of the conductor wires and got a shock,
nothing more than a mild tingle. Is the RCBO able to prevent a
significant electric shock? I will not be recommending or repeating
this.

I have been in this property for three years now and only recently
discovered that the downstairs study/dining room is connected to the
upstairs ring while all the other rooms are on the downstairs circuit.

As someone on the group to which I posted by mistake commented,
turning off the main switch is probably best practice (even if it does
mean resetting clocks afterwards).

Whatever kind of circuit you're going to work on, turn something on,
ideally the light or socket you'll be touching. Pull the fuse/breaker
and go straight back to confirm what you turned on is now dead.
Sometimes you will be surprised.

With an old enough installation, you could still be surprised. There was
a bang and a flash when my uncle cut a "dead" cable in the house he'd
moved into - he hadn't realised that it had fuses on both live and
neutral and he'd "isolated" the circuit by pulling the wrong one!

[Marland]

Post by SteveW
With an old enough installation, you could still be surprised. There was
a bang and a flash when my uncle cut a "dead" cable in the house he'd
moved into - he hadn't realised that it had fuses on both live and
neutral and he'd "isolated" the circuit by pulling the wrong one!

Was it a remnant of former DC supply that had been converted?


GH

[Scott]

Post by Marland

Post by SteveW
With an old enough installation, you could still be surprised. There was
a bang and a flash when my uncle cut a "dead" cable in the house he'd
moved into - he hadn't realised that it had fuses on both live and
neutral and he'd "isolated" the circuit by pulling the wrong one!

Was it a remnant of former DC supply that had been converted?

I have never understood neutral fusing though I had an idea it was a
DC feature. Was the black wire not referenced to earth then? Could
you get an electric shock from the black wire? Were three pin plugs
with an earth used in DC supplies? Would the whole house need to be
rewired for conversion from DC to AC?

[crn]

Post by Marland

Post by SteveW
With an old enough installation, you could still be surprised. There
was a bang and a flash when my uncle cut a "dead" cable in the house
he'd moved into - he hadn't realised that it had fuses on both live
and neutral and he'd "isolated" the circuit by pulling the wrong one!

Was it a remnant of former DC supply that had been converted?

I have never understood neutral fusing though I had an idea it was a DC
feature. Was the black wire not referenced to earth then? Could you get
an electric shock from the black wire? Were three pin plugs with an
earth used in DC supplies? Would the whole house need to be rewired for
conversion from DC to AC?

There has never been DC supplies to UK homes.
Some off-grid rural places used farm systems which were on site 32 volt DC
gererators with batteries. Now very rare.

[Bob Eager]

Post by crn
There has never been DC supplies to UK homes.

Wrong.


I grew up in Brighton and the whole town was DC until the late 1950s.

We had sockets with socking great switches that opened fast to minimise
the arc. And my model train set ran off 12v from a small rotary converter.

[Joe]

On 19 Feb 2025 11:13:47 GMT

Post by Bob Eager

Post by crn
There has never been DC supplies to UK homes.

Wrong.
I grew up in Brighton and the whole town was DC until the late 1950s.
We had sockets with socking great switches that opened fast to
minimise the arc. And my model train set ran off 12v from a small
rotary converter.

It was common for Sixties TVs and mains valve radios to be AC/DC, there
must have been a need. The Radiospares (not RS) catalogue in the late
Sixties contained many common mains dropper resistor banks, along with
wirewound sections to make your own if you had an unusual one.

[Andy Burns]

Post by Joe
The Radiospares (not RS) catalogue

I thought RS *is* the evolution of Radiospares?

[Joe]

On Wed, 19 Feb 2025 11:50:49 +0000

Post by Andy Burns

Post by Joe
The Radiospares (not RS) catalogue

I thought RS *is* the evolution of Radiospares?

Yes, I was just pointing out that it really was a supplier of radio and
TV spares then, the catalogue was stapled, and about 8mm thick.

[tony sayer]

Post by Joe
On Wed, 19 Feb 2025 11:50:49 +0000

Post by Andy Burns

Post by Joe
The Radiospares (not RS) catalogue

I thought RS *is* the evolution of Radiospares?

Yes, I was just pointing out that it really was a supplier of radio and
TV spares then, the catalogue was stapled, and about 8mm thick.

I remember a time when it was close to the thickness of the Beano!...

[Max Demian]

Post by Bob Eager

Post by crn
There has never been DC supplies to UK homes.

Wrong.
I grew up in Brighton and the whole town was DC until the late 1950s.
We had sockets with socking great switches that opened fast to minimise
the arc. And my model train set ran off 12v from a small rotary converter.

I thought that originally they were connected to 100 VDC via a bulb that
dropped the voltage. Until the train derailed and the middle rail went
up to 100V.

(Good job kids were tough in those days.)

[Graeme]

Post by Max Demian

Post by Bob Eager
my model train set ran off 12v from a small rotary converter.

I thought that originally they were connected to 100 VDC via a bulb
that dropped the voltage. Until the train derailed and the middle rail
went up to 100V.

That was the earlier (1930s) Hornby, and others. The Hornby 0 gauge
Metropolitan loco was issued as High Voltage then 6v, then the more
usual 20v.

Bob's, in the 50s, was probably Hornby Dublo. Possibly Trix or even
early Tri-ang.

[Bob Eager]

Post by Graeme

Post by Max Demian

Post by Bob Eager
my model train set ran off 12v from a small rotary converter.

I thought that originally they were connected to 100 VDC via a bulb that
dropped the voltage. Until the train derailed and the middle rail went
up to 100V.

That was the earlier (1930s) Hornby, and others. The Hornby 0 gauge
Metropolitan loco was issued as High Voltage then 6v, then the more
usual 20v.
Bob's, in the 50s, was probably Hornby Dublo. Possibly Trix or even
early Tri-ang.

It was definitely Tri-Ang. My father made a massive layout on a board, for
a Christmas present for my brother and me. It was on rollers and the
signals folded down so it fitted under our bunk beds.

[Max Demian]

Post by Bob Eager

Post by Graeme

Post by Max Demian

Post by Bob Eager
my model train set ran off 12v from a small rotary converter.

I thought that originally they were connected to 100 VDC via a bulb that
dropped the voltage. Until the train derailed and the middle rail went
up to 100V.

That was the earlier (1930s) Hornby, and others. The Hornby 0 gauge
Metropolitan loco was issued as High Voltage then 6v, then the more
usual 20v.
Bob's, in the 50s, was probably Hornby Dublo. Possibly Trix or even
early Tri-ang.

It was definitely Tri-Ang. My father made a massive layout on a board, for
a Christmas present for my brother and me. It was on rollers and the
signals folded down so it fitted under our bunk beds.

Did he play with it more than you did?

[Marland]

Post by Max Demian

Post by Bob Eager

Post by crn
There has never been DC supplies to UK homes.

Wrong.
I grew up in Brighton and the whole town was DC until the late 1950s.
We had sockets with socking great switches that opened fast to minimise
the arc. And my model train set ran off 12v from a small rotary converter.

I thought that originally they were connected to 100 VDC via a bulb that
dropped the voltage. Until the train derailed and the middle rail went
up to 100V.
(Good job kids were tough in those days.)

the original Hornby electric used 100 volts anyway. I think they were only
in production for a short period.

<https://collection.powerhouse.com.au/object/44567>

GH

[SteveW]

Post by Max Demian

Post by Bob Eager

Post by crn
There has never been DC supplies to UK homes.

Wrong.
I grew up in Brighton and the whole town was DC until the late 1950s.
We had sockets with socking great switches that opened fast to minimise
the arc. And my model train set ran off 12v from a small rotary converter.

I thought that originally they were connected to 100 VDC via a bulb that
dropped the voltage. Until the train derailed and the middle rail went
up to 100V.

I've certainly seen one like that in a toy museum.

[Scott]

Post by SteveW

Post by Max Demian

Post by Bob Eager

Post by crn
There has never been DC supplies to UK homes.

Wrong.
I grew up in Brighton and the whole town was DC until the late 1950s.
We had sockets with socking great switches that opened fast to minimise
the arc. And my model train set ran off 12v from a small rotary converter.

I thought that originally they were connected to 100 VDC via a bulb that
dropped the voltage. Until the train derailed and the middle rail went
up to 100V.

I've certainly seen one like that in a toy museum.

Where did the 100 Volts DC come from?

[SteveW]

Post by Scott

Post by SteveW

Post by Max Demian

Post by Bob Eager

Post by crn
There has never been DC supplies to UK homes.

Wrong.
I grew up in Brighton and the whole town was DC until the late 1950s.
We had sockets with socking great switches that opened fast to minimise
the arc. And my model train set ran off 12v from a small rotary converter.

I thought that originally they were connected to 100 VDC via a bulb that
dropped the voltage. Until the train derailed and the middle rail went
up to 100V.

I've certainly seen one like that in a toy museum.

Where did the 100 Volts DC come from?

When houses were supplied with DC, by unplugging the light bulb,
plugging in the railway controller and plugging the light bulb into the
top of the controller as a dropper resistor.

[Scott]

Post by SteveW

Post by Scott

Post by SteveW

Post by Max Demian

Post by Bob Eager

Post by crn
There has never been DC supplies to UK homes.

Wrong.
I grew up in Brighton and the whole town was DC until the late 1950s.
We had sockets with socking great switches that opened fast to minimise
the arc. And my model train set ran off 12v from a small rotary converter.

I thought that originally they were connected to 100 VDC via a bulb that
dropped the voltage. Until the train derailed and the middle rail went
up to 100V.

I've certainly seen one like that in a toy museum.

Where did the 100 Volts DC come from?

When houses were supplied with DC, by unplugging the light bulb,
plugging in the railway controller and plugging the light bulb into the
top of the controller as a dropper resistor.

I still don't follow this. Are you saying the supply voltage was 100
Volts (which would surprise me greatly) or that the supply voltage was
something like 200 Volts dropped to 100 Volts by the light bulb. What
is the relevance of the train being derailed? Surely this would not
affect the voltage of the live rail?

[Max Demian]

Post by Scott

Post by SteveW

Post by Scott

Post by SteveW

Post by Max Demian

Post by Bob Eager

Post by crn
There has never been DC supplies to UK homes.

Wrong.
I grew up in Brighton and the whole town was DC until the late 1950s.
We had sockets with socking great switches that opened fast to minimise
the arc. And my model train set ran off 12v from a small rotary converter.

I thought that originally they were connected to 100 VDC via a bulb that
dropped the voltage. Until the train derailed and the middle rail went
up to 100V.

I've certainly seen one like that in a toy museum.

Where did the 100 Volts DC come from?

When houses were supplied with DC, by unplugging the light bulb,
plugging in the railway controller and plugging the light bulb into the
top of the controller as a dropper resistor.

I still don't follow this. Are you saying the supply voltage was 100
Volts (which would surprise me greatly) or that the supply voltage was
something like 200 Volts dropped to 100 Volts by the light bulb. What
is the relevance of the train being derailed? Surely this would not
affect the voltage of the live rail?

I don't know what the voltages were before and after dropping, but
clearly if the train isn't taking any current the voltage will rise to
the supply voltage.

[Marland]

Post by Scott

Post by SteveW

Post by Scott

Post by SteveW

Post by Max Demian

Post by Bob Eager
We had sockets with socking great switches that opened fast to minimise
the arc. And my model train set ran off 12v from a small rotary converter.

I thought that originally they were connected to 100 VDC via a bulb that
dropped the voltage. Until the train derailed and the middle rail went
up to 100V.

I've certainly seen one like that in a toy museum.

Where did the 100 Volts DC come from?

When houses were supplied with DC, by unplugging the light bulb,
plugging in the railway controller and plugging the light bulb into the
top of the controller as a dropper resistor.

I still don't follow this. Are you saying the supply voltage was 100
Volts (which would surprise me greatly) or that the supply voltage was
something like 200 Volts dropped to 100 Volts by the light bulb. What
is the relevance of the train being derailed? Surely this would not
affect the voltage of the live rail?

Hornby basically copied the method already used by the German toy makers of
the early 20th century who were no longer popular in Britain after WW1.
Ironically just as the Germans were deciding that it was too dangerous.
Have a read of this which may answer your questions

<
https://marklinstop.com/2015/07/220-volts-to-the-present-from-life-threatening-danger-to-safety/>

GH

[SteveW]

Post by Marland

Post by Scott

Post by SteveW

Post by Scott

Post by SteveW

Post by Max Demian

Post by Bob Eager
We had sockets with socking great switches that opened fast to minimise
the arc. And my model train set ran off 12v from a small rotary converter.

I thought that originally they were connected to 100 VDC via a bulb that
dropped the voltage. Until the train derailed and the middle rail went
up to 100V.

I've certainly seen one like that in a toy museum.

Where did the 100 Volts DC come from?

When houses were supplied with DC, by unplugging the light bulb,
plugging in the railway controller and plugging the light bulb into the
top of the controller as a dropper resistor.

I still don't follow this. Are you saying the supply voltage was 100
Volts (which would surprise me greatly) or that the supply voltage was
something like 200 Volts dropped to 100 Volts by the light bulb. What
is the relevance of the train being derailed? Surely this would not
affect the voltage of the live rail?

Hornby basically copied the method already used by the German toy makers of
the early 20th century who were no longer popular in Britain after WW1.
Ironically just as the Germans were deciding that it was too dangerous.
Have a read of this which may answer your questions
<
https://marklinstop.com/2015/07/220-volts-to-the-present-from-life-threatening-danger-to-safety/>

Thanks for the link.

[Scott]

On Wed, 19 Feb 2025 12:35:24 +0000, Max Demian

Post by Max Demian

Post by Bob Eager

Post by crn
There has never been DC supplies to UK homes.

Wrong.
I grew up in Brighton and the whole town was DC until the late 1950s.
We had sockets with socking great switches that opened fast to minimise
the arc. And my model train set ran off 12v from a small rotary converter.

I thought that originally they were connected to 100 VDC via a bulb that
dropped the voltage. Until the train derailed and the middle rail went
up to 100V.
(Good job kids were tough in those days.)

I remember vague warnings about getting an electric shock from the
train set, which I thought were far-fetched at the time as the voltage
was 12V DC (or I think 15V AC for points motors?).

However, when I used the transformer to electrolyse salt water then
collected the chlorine in a jar then sniffed it, I did get a different
type of shock to the system.

[Andrew]

Post by Bob Eager

Post by crn
There has never been DC supplies to UK homes.

Wrong.
I grew up in Brighton and the whole town was DC until the late 1950s.

Volks railway still is :-)

Post by Bob Eager
We had sockets with socking great switches that opened fast to minimise
the arc. And my model train set ran off 12v from a small rotary converter.

[Bob Eager]

Post by Andrew

Post by Bob Eager

Post by crn
There has never been DC supplies to UK homes.

Wrong.
I grew up in Brighton and the whole town was DC until the late 1950s.

Volks railway still is :-)

Indeed it is! Still fun to have a ride on it.

They had the power plant in the arches near Duke's Mound, and I think they
still do.

[Andy Burns]

Post by crn
There has never been DC supplies to UK homes.

Oh?

<https://www.vintage-radio.net/forum/showthread.php?t=149636>

I think residential areas of north Nottingham were late to be converted
to AC.

[Scott]

Post by crn

Post by Marland

Post by SteveW
With an old enough installation, you could still be surprised. There
was a bang and a flash when my uncle cut a "dead" cable in the house
he'd moved into - he hadn't realised that it had fuses on both live
and neutral and he'd "isolated" the circuit by pulling the wrong one!

Was it a remnant of former DC supply that had been converted?

I have never understood neutral fusing though I had an idea it was a DC
feature. Was the black wire not referenced to earth then? Could you get
an electric shock from the black wire? Were three pin plugs with an
earth used in DC supplies? Would the whole house need to be rewired for
conversion from DC to AC?

There has never been DC supplies to UK homes.
Some off-grid rural places used farm systems which were on site 32 volt DC
gererators with batteries. Now very rare.

https://www.vintage-radio.net/forum/showthread.php?t=41380

(eg) A quick scan of the Electricity Supply handbook for 1965, shows a
number of London districts, e.g. Acton South, Battersea, Hounslow, and
others being supplied with 230/415V 3 wire DC. Other examples are
Middlesborough and York, 230V 2 wire, and Nottingham, 200/400V 3 wire.

[Marland]

Post by crn
There has never been DC supplies to UK homes.

Don’t talk bollocks .

Many places once had DC supplies at various voltages in the early days of
electric supply when power came from smaller local power stations.

The final pockets lasted until the 1970’s. One was part of Exeter around
the City Basin area
another was Reading which had some DC areas into the 1960’s.

GH

[tony sayer]

Post by Marland

Post by crn
There has never been DC supplies to UK homes.

Don’t talk bollocks .
Many places once had DC supplies at various voltages in the early days of
electric supply when power came from smaller local power stations.
The final pockets lasted until the 1970’s. One was part of Exeter around
the City Basin area
another was Reading which had some DC areas into the 1960’s.
GH

This is from Cambridge in 1891. Then we had Thompson's lane next the
river( Very useful for the coal supplied by barge) come online at 200
volts AC!. I think one of the early gennies is in the science museum!..



1891 The building where the first electricity for lighting in Cambridge
was generated is now on the market. The property, No.2 Market Passage,
was the premises of Bailey, Grundy and Barrett, electrical contractors.

In 1891 the firm produced the first electricity for lighting in the city
with a gas engine and a dynamo installed in the basement. In those early
days private electrical generating plants were supplied by the company
to several of the Cambridge colleges. Until after the 1914-18 war such
plants continued to be installed in country houses in outlying
districts. As this business declined, the company moved into wireless,
the design and making of temperature control equipment for laboratories
and other specialised apparatus.

[charles]

Post by tony sayer

Post by crn
There has never been DC supplies to UK homes.

Don‘t talk bollocks .
Many places once had DC supplies at various voltages in the early days of
electric supply when power came from smaller local power stations.
The final pockets lasted until the 1970‘s. One was part of Exeter around
the City Basin area
another was Reading which had some DC areas into the 1960‘s.
GH

This is from Cambridge in 1891. Then we had Thompson's lane next the
river( Very useful for the coal supplied by barge) come online at 200
volts AC!. I think one of the early gennies is in the science museum!..

In the early 1960s it was still 200v ac.

Post by tony sayer
1891 The building where the first electricity for lighting in Cambridge
was generated is now on the market. The property, No.2 Market Passage,
was the premises of Bailey, Grundy and Barrett, electrical contractors.
In 1891 the firm produced the first electricity for lighting in the city
with a gas engine and a dynamo installed in the basement. In those early
days private electrical generating plants were supplied by the company
to several of the Cambridge colleges. Until after the 1914-18 war such
plants continued to be installed in country houses in outlying
districts. As this business declined, the company moved into wireless,
the design and making of temperature control equipment for laboratories
and other specialised apparatus.
--
To

[John R Walliker]

Post by charles

Post by tony sayer

Post by crn
There has never been DC supplies to UK homes.

Don‘t talk bollocks .
Many places once had DC supplies at various voltages in the early days of
electric supply when power came from smaller local power stations.
The final pockets lasted until the 1970‘s. One was part of Exeter around
the City Basin area
another was Reading which had some DC areas into the 1960‘s.
GH

This is from Cambridge in 1891. Then we had Thompson's lane next the
river( Very useful for the coal supplied by barge) come online at 200
volts AC!. I think one of the early gennies is in the science museum!..

The London science museum had a large dc supply provided by a
three-phase mercury arc rectifier which was itself on display
in a large glass cabinet.

John

Post by charles
In the early 1960s it was still 200v ac.

Post by tony sayer
1891 The building where the first electricity for lighting in Cambridge
was generated is now on the market. The property, No.2 Market Passage,
was the premises of Bailey, Grundy and Barrett, electrical contractors.
In 1891 the firm produced the first electricity for lighting in the city
with a gas engine and a dynamo installed in the basement. In those early
days private electrical generating plants were supplied by the company
to several of the Cambridge colleges. Until after the 1914-18 war such
plants continued to be installed in country houses in outlying
districts. As this business declined, the company moved into wireless,
the design and making of temperature control equipment for laboratories
and other specialised apparatus.
--
To

[Jeff Layman]

Post by John R Walliker

Post by tony sayer

Post by crn
There has never been DC supplies to UK homes.

Don‘t talk bollocks .
Many places once had DC supplies at various voltages in the early days of
electric supply when power came from smaller local power stations.
The final pockets lasted until the 1970‘s. One was part of Exeter around
the City Basin area
another was Reading which had some DC areas into the 1960‘s.
GH

This is from Cambridge in 1891. Then we had Thompson's lane next the
river( Very useful for the coal supplied by barge) come online at 200
volts AC!. I think one of the early gennies is in the science museum!..

The London science museum had a large dc supply provided by a
three-phase mercury arc rectifier which was itself on display
in a large glass cabinet.

Indeed. Every time I visited the museum as a child I used to find it
fascinating to watch the arc. It wasn't until much later that I wondered
about the extreme amount of UV light being being generated and whether
or not it was screened off
(<https://en.wikipedia.org/wiki/Mercury-vapor_lamp#Ultraviolet_hazards>)!

[The Nomad]

Post by Jeff Layman

Post by John R Walliker

Post by tony sayer

Post by crn
There has never been DC supplies to UK homes.

Don‘t talk bollocks .
Many places once had DC supplies at various voltages in the early
days of electric supply when power came from smaller local power
stations.
The final pockets lasted until the 1970‘s. One was part of Exeter
around the City Basin area another was Reading which had some DC
areas into the 1960‘s.
GH

This is from Cambridge in 1891. Then we had Thompson's lane next the
river( Very useful for the coal supplied by barge) come online at
200 volts AC!. I think one of the early gennies is in the science
museum!..

The London science museum had a large dc supply provided by a
three-phase mercury arc rectifier which was itself on display in a
large glass cabinet.

Indeed. Every time I visited the museum as a child I used to find it
fascinating to watch the arc. It wasn't until much later that I wondered
about the extreme amount of UV light being being generated and whether
or not it was screened off
(<https://en.wikipedia.org/wiki/Mercury-

vapor_lamp#Ultraviolet_hazards>)!

I'd love to see/hear this IRL

Avpx

[Max Demian]

Post by John R Walliker

Post by tony sayer

Post by crn
There has never been DC supplies to UK homes.

Don‘t talk bollocks .
Many places once had DC supplies at various voltages in the early days of
electric supply when power came from smaller local power stations.
The final pockets lasted until the 1970‘s. One was part of Exeter around
the City Basin area
another was Reading which had some DC areas into the 1960‘s.

This is from Cambridge in 1891. Then we had Thompson's lane next the
river( Very useful for the coal supplied by barge)  come online at 200
volts AC!. I think one of the early gennies is in the science museum!..

The London science museum had a large dc supply provided by a
three-phase mercury arc rectifier which was itself on display
in a large glass cabinet.

Up until the major refurbishment around the Millennium, the stage
machinery for the Royal Opera House, Covent Garden, was driven by WW1
submarine motors supplied with DC through mercury arc rectifiers. (Of
course the motors would be DC as the submarines were powered by lead
acid batteries.)

I went on tours of the ROH before and after the refurbishment. I should
have asked to see the rectifiers if possible.

[tony sayer]

Post by charles

Post by tony sayer

Post by crn
There has never been DC supplies to UK homes.

Don‘t talk bollocks .
Many places once had DC supplies at various voltages in the early days of
electric supply when power came from smaller local power stations.
The final pockets lasted until the 1970‘s. One was part of Exeter around
the City Basin area
another was Reading which had some DC areas into the 1960‘s.
GH

This is from Cambridge in 1891. Then we had Thompson's lane next the
river( Very useful for the coal supplied by barge) come online at 200
volts AC!. I think one of the early gennies is in the science museum!..

In the early 1960s it was still 200v ac.

It was still 200 volts into the 1970's as i had to bridge out dropper
resistors in TV's to make then work properly!. The Thompsons lane
station had shut but there were local transformers supplying the 200
volts still..
Ah! we've had this argument before Charles, the Thompsons lane was AC
but the 1891 Baily Grundy and Barrett was DC there was an article on
that somewhere but sodded if i can find it now.

Seems that the Thompsons lane sets were supplied by none other than
Charges Algernon Parsons he of the Turbina ship fame educated at St
Johns here it appears!..


https://collection.sciencemuseumgroup.org.uk/people/ap26725/parsons-
charles-algernon

https://collection.sciencemuseumgroup.org.uk/objects/co8625819/100-k-w-
parsons-radial-flow-steam-turbine-alternator-with-generator-partly-
sectioned-engine-turbine

Post by charles

Post by tony sayer
1891 The building where the first electricity for lighting in Cambridge
was generated is now on the market. The property, No.2 Market Passage,
was the premises of Bailey, Grundy and Barrett, electrical contractors.
In 1891 the firm produced the first electricity for lighting in the city
with a gas engine and a dynamo installed in the basement. In those early
days private electrical generating plants were supplied by the company
to several of the Cambridge colleges. Until after the 1914-18 war such
plants continued to be installed in country houses in outlying
districts. As this business declined, the company moved into wireless,
the design and making of temperature control equipment for laboratories
and other specialised apparatus.
--
To

[SteveW]

Post by crn

Post by Marland

Post by SteveW
With an old enough installation, you could still be surprised. There
was a bang and a flash when my uncle cut a "dead" cable in the house
he'd moved into - he hadn't realised that it had fuses on both live
and neutral and he'd "isolated" the circuit by pulling the wrong one!

Was it a remnant of former DC supply that had been converted?

I have never understood neutral fusing though I had an idea it was a DC
feature. Was the black wire not referenced to earth then? Could you get
an electric shock from the black wire? Were three pin plugs with an
earth used in DC supplies? Would the whole house need to be rewired for
conversion from DC to AC?

There has never been DC supplies to UK homes.
Some off-grid rural places used farm systems which were on site 32 volt DC
gererators with batteries. Now very rare.

DC supplies to home were common, as were different voltages, until
standardisation on AC and the construction of the grid.

[SteveW]

Post by Marland

Post by SteveW
With an old enough installation, you could still be surprised. There was
a bang and a flash when my uncle cut a "dead" cable in the house he'd
moved into - he hadn't realised that it had fuses on both live and
neutral and he'd "isolated" the circuit by pulling the wrong one!

Was it a remnant of former DC supply that had been converted?

Maybe just about possible with the age.

[Andrew]

Post by Scott

Post by Jeff Gaines

Post by Scott
It looks like I am in the hall of shame. To change a lightswitch, I
switched off the downstairs RCBO forgetting that the switch at the
bottom of the stairs was connected to a light fed from the upstairs
circuit. I touched one of the conductor wires and got a shock, nothing
more than a mild tingle. Is the RCBO able to prevent a significant
electric shock? I will not be recommending or repeating this.

I have been in this property for three years now and only recently
discovered that the downstairs study/dining room is connected to the
upstairs ring while all the other rooms are on the downstairs circuit.

As someone on the group to which I posted by mistake commented,
turning off the main switch is probably best practice (even if it does
mean resetting clocks afterwards).

People on ADSL might find that their download speeds suffer while
the line 're-learns' the correct speed though. Happened to me.

[SteveW]

Post by Andrew

Post by Scott

Post by Jeff Gaines

Post by Scott
It looks like I am in the hall of shame. To change a lightswitch, I
switched off the downstairs RCBO forgetting that the switch at the
bottom of the stairs was connected to a light fed from the upstairs
circuit. I touched one of the conductor wires and got a shock, nothing
more than a mild tingle. Is the RCBO able to prevent a significant
electric shock? I will not be recommending or repeating this.

I have been in this property for three years now and only recently
discovered that the downstairs study/dining room is connected to the
upstairs ring while all the other rooms are on the downstairs circuit.

As someone on the group to which I posted by mistake commented,
turning off the main switch is probably best practice (even if it does
mean resetting clocks afterwards).

People on ADSL might find that their download speeds suffer while
the line 're-learns' the correct speed though. Happened to me.

For us, we don't want to shutdown our home server, network switch and
router - as that kills email for all our phones, including two of our
sons away at university and stops their access to our network, where
they store their university work. It also disables the "landline" and
often the server does not reboot first time (a race condition between
devices starting) and as it has no monitor connected, it's a pain to see
what's happened.

[charles]

Post by SteveW

Post by Andrew

Post by Scott

Post by Jeff Gaines

Post by Scott
It looks like I am in the hall of shame. To change a lightswitch, I
switched off the downstairs RCBO forgetting that the switch at the
bottom of the stairs was connected to a light fed from the upstairs
circuit. I touched one of the conductor wires and got a shock, nothing
more than a mild tingle. Is the RCBO able to prevent a significant
electric shock? I will not be recommending or repeating this.

I have been in this property for three years now and only recently
discovered that the downstairs study/dining room is connected to the
upstairs ring while all the other rooms are on the downstairs circuit.

As someone on the group to which I posted by mistake commented,
turning off the main switch is probably best practice (even if it does
mean resetting clocks afterwards).

People on ADSL might find that their download speeds suffer while
the line 're-learns' the correct speed though. Happened to me.

For us, we don't want to shutdown our home server, network switch and
router - as that kills email for all our phones, including two of our
sons away at university and stops their access to our network, where
they store their university work. It also disables the "landline" and
often the server does not reboot first time (a race condition between
devices starting) and as it has no monitor connected, it's a pain to see
what's happened.

If it's that important, you should have a UPS - in case of mains failure.

[SteveW]

Post by charles

Post by SteveW

Post by Andrew

Post by Scott

Post by Jeff Gaines

Post by Scott
It looks like I am in the hall of shame. To change a lightswitch, I
switched off the downstairs RCBO forgetting that the switch at the
bottom of the stairs was connected to a light fed from the upstairs
circuit. I touched one of the conductor wires and got a shock, nothing
more than a mild tingle. Is the RCBO able to prevent a significant
electric shock? I will not be recommending or repeating this.

I have been in this property for three years now and only recently
discovered that the downstairs study/dining room is connected to the
upstairs ring while all the other rooms are on the downstairs circuit.

As someone on the group to which I posted by mistake commented,
turning off the main switch is probably best practice (even if it does
mean resetting clocks afterwards).

People on ADSL might find that their download speeds suffer while
the line 're-learns' the correct speed though. Happened to me.

For us, we don't want to shutdown our home server, network switch and
router - as that kills email for all our phones, including two of our
sons away at university and stops their access to our network, where
they store their university work. It also disables the "landline" and
often the server does not reboot first time (a race condition between
devices starting) and as it has no monitor connected, it's a pain to see
what's happened.

If it's that important, you should have a UPS - in case of mains failure.

We do, but it is intended to ride out short interruptions or provide for
graceful shutdown on longer ones, not to keep everything running for an
extended period.

[charles]

Post by Jeff Gaines

Post by Scott
It looks like I am in the hall of shame. To change a lightswitch, I
switched off the downstairs RCBO forgetting that the switch at the
bottom of the stairs was connected to a light fed from the upstairs
circuit. I touched one of the conductor wires and got a shock, nothing
more than a mild tingle. Is the RCBO able to prevent a significant
electric shock? I will not be recommending or repeating this.

I have been in this property for three years now and only recently
discovered that the downstairs study/dining room is connected to the
upstairs ring while all the other rooms are on the downstairs circuit.

I have a couple of sockets downstairs which are fed from the "upstairs
ring". I have labelled them to this effect for someone in the future.

[SteveW]

Post by charles

Post by Jeff Gaines

Post by Scott
It looks like I am in the hall of shame. To change a lightswitch, I
switched off the downstairs RCBO forgetting that the switch at the
bottom of the stairs was connected to a light fed from the upstairs
circuit. I touched one of the conductor wires and got a shock, nothing
more than a mild tingle. Is the RCBO able to prevent a significant
electric shock? I will not be recommending or repeating this.

I have been in this property for three years now and only recently
discovered that the downstairs study/dining room is connected to the
upstairs ring while all the other rooms are on the downstairs circuit.

I have a couple of sockets downstairs which are fed from the "upstairs
ring". I have labelled them to this effect for someone in the future.

Hall light fed from upstairs lights (as it is double switched);
conservatory lights fed (via an FCU) from the downstairs ring (as that
could be extended into it easily); downstairs heating valves and
underfloor heating pump fed from upstairs (as that it where most of the
valves and the main pump are) and cables down to the wall-hung boiler.
No other oddities. All down on drawings for the future.

I can highly recommend having the hall/landing lights fed from upstairs
rather than downstairs. When I came in during the early hours of the
morning, the hall light blew as I turned it on and tripped the breaker.
Opening the kitchen door and putting that light on meant that I could
see to disable the alarm before it went off and woke all the neighbours!

[Andy Burns]

Post by Jeff Gaines
I have been in this property for three years now and only recently
discovered that the downstairs study/dining room is connected to the
upstairs ring while all the other rooms are on the downstairs circuit.

Contact or non-contact probes aren't expensive ...
<https://www.screwfix.com/c/tools/voltage-testers/cat7910007>

[Andrew]

Post by Jeff Gaines

Post by Scott
It looks like I am in the hall of shame. To change a lightswitch, I
switched off the downstairs RCBO forgetting that the switch at the
bottom of the stairs was connected to a light fed from the upstairs
circuit. I touched one of the conductor wires and got a shock, nothing
more than a mild tingle. Is the RCBO able to prevent a significant
electric shock? I will not be recommending or repeating this.

I have been in this property for three years now and only recently
discovered that the downstairs study/dining room is connected to the
upstairs ring while all the other rooms are on the downstairs circuit.

Is it a bungalow ? :-)

[Jeff Gaines]

Post by Andrew

Post by Jeff Gaines

Post by Scott
It looks like I am in the hall of shame. To change a lightswitch, I
switched off the downstairs RCBO forgetting that the switch at the
bottom of the stairs was connected to a light fed from the upstairs
circuit. I touched one of the conductor wires and got a shock, nothing
more than a mild tingle. Is the RCBO able to prevent a significant
electric shock? I will not be recommending or repeating this.

I have been in this property for three years now and only recently
discovered that the downstairs study/dining room is connected to the
upstairs ring while all the other rooms are on the downstairs circuit.

Is it a bungalow ? :-)

Chalet bungalow :-)

[Andrew]

Post by Jeff Gaines

Post by Andrew

Post by Jeff Gaines

Post by Scott
It looks like I am in the hall of shame. To change a lightswitch, I
switched off the downstairs RCBO forgetting that the switch at the
bottom of the stairs was connected to a light fed from the upstairs
circuit. I touched one of the conductor wires and got a shock, nothing
more than a mild tingle. Is the RCBO able to prevent a significant
electric shock? I will not be recommending or repeating this.

I have been in this property for three years now and only recently
discovered that the downstairs study/dining room is connected to the
upstairs ring while all the other rooms are on the downstairs circuit.

Is it a bungalow ? :-)

Chalet bungalow :-)

BRRR. Little or no insulation inside those sloping upstairs
'walls', especially if it was built in the 50's or 60's (or
70's, or ...)

I heard a tale that many were built during periods when bricks
were expensive

[Jeff Gaines]

Post by Andrew

Post by Jeff Gaines

Post by Andrew

Post by Jeff Gaines

Post by Scott
It looks like I am in the hall of shame. To change a lightswitch, I
switched off the downstairs RCBO forgetting that the switch at the
bottom of the stairs was connected to a light fed from the upstairs
circuit. I touched one of the conductor wires and got a shock, nothing
more than a mild tingle. Is the RCBO able to prevent a significant
electric shock? I will not be recommending or repeating this.

I have been in this property for three years now and only recently
discovered that the downstairs study/dining room is connected to the
upstairs ring while all the other rooms are on the downstairs circuit.

Is it a bungalow ? :-)

Chalet bungalow :-)

BRRR. Little or no insulation inside those sloping upstairs
'walls', especially if it was built in the 50's or 60's (or
70's, or ...)
I heard a tale that many were built during periods when bricks
were expensive

Built 1983. Very solid, cavity insulation, dormer walls have 6" rock wool,
loft has about 12" except it's about 4' where they stacked up what was
left over. Under floor allegedly insulated and if you want to fix anything
to the outside walls you put the plugs in the mortar unless you have a
diamond drill!

Avocado suites and Artex ceilings, absolutely pristine. Have to be careful
about the Artex in case it was old stock.

Gas CH, just had new boiler fitted, will see me out!

[Andrew]

Post by Jeff Gaines

Post by Andrew

Post by Jeff Gaines

Post by Andrew

On 18/02/2025 in message

Post by Scott
It looks like I am in the hall of shame. To change a lightswitch, I
switched off the downstairs RCBO forgetting that the switch at the
bottom of the stairs was connected to a light fed from the upstairs
circuit. I touched one of the conductor wires and got a shock, nothing
more than a mild tingle. Is the RCBO able to prevent a significant
electric shock? I will not be recommending or repeating this.

I have been in this property for three years now and only recently
discovered that the downstairs study/dining room is connected to
the upstairs ring while all the other rooms are on the downstairs
circuit.

Is it a bungalow ? :-)

Chalet bungalow :-)

BRRR. Little or no insulation inside those sloping upstairs
'walls', especially if it was built in the 50's or 60's (or
70's, or ...)
I heard a tale that many were built during periods when bricks
were expensive

Built 1983. Very solid, cavity insulation, dormer walls have 6" rock
wool, loft has about 12" except it's about 4' where they stacked up what
was left over. Under floor allegedly insulated and if you want to fix
anything to the outside walls you put the plugs in the mortar unless you
have a diamond drill!
Avocado suites and Artex ceilings, absolutely pristine. Have to be
careful about the Artex in case it was old stock.

One man's Avocado is another man's Pampas Green (which is much
lighter in colour).

PS what is the modern era equivalent of planting a Pampas grass
in the middle of the front lawn ?. (wife swapping).

[Andy Burns]

Post by Scott
It looks like I am in the hall of shame. To change a lightswitch, I
switched off the downstairs RCBO forgetting that the switch at the
bottom of the stairs was connected to a light fed from the upstairs
circuit. I touched one of the conductor wires and got a shock, nothing
more than a mild tingle. Is the RCBO able to prevent a significant
electric shock?

Disconnect time for 30µA RCD/RCBO should be under 300ms, often they're
faster than that ...

[SH]

Post by Andy Burns

Post by Scott
It looks like I am in the hall of shame. To change a lightswitch, I
switched off the downstairs RCBO forgetting that the switch at the
bottom of the stairs was connected to a light fed from the upstairs
circuit. I touched one of the conductor wires and got a shock, nothing
more than a mild tingle. Is the RCBO able to prevent a significant
electric shock?

Disconnect time for 30µA RCD/RCBO should be under 300ms, often they're
faster than that ...

since when did 30µA RCD/RCBOs exist?

The lowest I can find is 30 mA.....

[Andy Burns]

Post by SH

Post by Andy Burns
Disconnect time for 30µA RCD/RCBO should be under 300ms, often they're
faster than that ...

since when did 30µA RCD/RCBOs exist?

My brain thought two "milli" prefixes looked wrong :-P

[Chris Green]

Post by Andy Burns

Post by Scott
It looks like I am in the hall of shame. To change a lightswitch, I
switched off the downstairs RCBO forgetting that the switch at the
bottom of the stairs was connected to a light fed from the upstairs
circuit. I touched one of the conductor wires and got a shock, nothing
more than a mild tingle. Is the RCBO able to prevent a significant
electric shock?

Disconnect time for 30µA RCD/RCBO should be under 300ms, often they're
faster than that ...

30mA surely.

[No mail]

Post by Scott
It looks like I am in the hall of shame. To change a lightswitch, I
switched off the downstairs RCBO forgetting that the switch at the
bottom of the stairs was connected to a light fed from the upstairs
circuit. I touched one of the conductor wires and got a shock, nothing
more than a mild tingle. Is the RCBO able to prevent a significant
electric shock? I will *not* be recommending or repeating this.

Always confirm a circuit is dead. Easiest way is with a non-contact
sensor. First check the sensor is working using a known live
somethingorother, then check your circuit is dead, then re-check your
sensor is still working on a live wire.

[tony sayer]

Post by No mail

Post by Scott
It looks like I am in the hall of shame. To change a lightswitch, I
switched off the downstairs RCBO forgetting that the switch at the
bottom of the stairs was connected to a light fed from the upstairs
circuit. I touched one of the conductor wires and got a shock, nothing
more than a mild tingle. Is the RCBO able to prevent a significant
electric shock? I will *not* be recommending or repeating this.

Always confirm a circuit is dead. Easiest way is with a non-contact
sensor. First check the sensor is working using a known live
somethingorother, then check your circuit is dead, then re-check your
sensor is still working on a live wire.

When i used to work at Pye Television transmitters we had a three phase
transformer that used to wind up the 415 volt AC mains to around 15 kV
for the high voltage Klystron supplies we were supplying these units to
Korea IIRC.

Anyway one of the Korean men showed us how to check the 15 kV supply was
off, he just banged the earthing stick across the incoming mains on the
transformer.

Bloody great bang and flash and the whole factory went out, he was shall
we say shaken and stirred!...

[No mail]

Post by tony sayer

Post by No mail

Post by Scott
It looks like I am in the hall of shame. To change a lightswitch, I
switched off the downstairs RCBO forgetting that the switch at the
bottom of the stairs was connected to a light fed from the upstairs
circuit. I touched one of the conductor wires and got a shock, nothing
more than a mild tingle. Is the RCBO able to prevent a significant
electric shock? I will *not* be recommending or repeating this.

Always confirm a circuit is dead. Easiest way is with a non-contact
sensor. First check the sensor is working using a known live
somethingorother, then check your circuit is dead, then re-check your
sensor is still working on a live wire.

When i used to work at Pye Television transmitters we had a three phase
transformer that used to wind up the 415 volt AC mains to around 15 kV
for the high voltage Klystron supplies we were supplying these units to
Korea IIRC.
Anyway one of the Korean men showed us how to check the 15 kV supply was
off, he just banged the earthing stick across the incoming mains on the
transformer.
Bloody great bang and flash and the whole factory went out, he was shall
we say shaken and stirred!...

Many years ago, when I was naive and developing CRT-based PC display
systems, I was trying to solve a jitter problem. To rule out anything
from the supply side I built a huge capacitor bank so I could run the
display from DC for a while. I knew the caps should have bleed resistors
but I didn't have anything suitable, and time was short, so didn't
bother with them. I finished the test and left the kit for a few hours.
When I returned to dismantle everything I decided to check it was safe
by shorting with a screwdriver. The resulting bang affected my hearing
for a looong time (and may still be doing so), people came running down
the corridor (I was in a separate office, with the door shut, for
safety) because they thought there had been an explosion, and most of
the screwdriver had disappeared. I knew about the need for bleeds, and
about the dangers of dielectric absorption, from Uni and earlier work
but was overconfident. Hubris lead to (near) nemesis.
I was shaken, stirred, ... and deaf!

[SteveW]

Post by tony sayer

Post by No mail

Post by Scott
It looks like I am in the hall of shame. To change a lightswitch, I
switched off the downstairs RCBO forgetting that the switch at the
bottom of the stairs was connected to a light fed from the upstairs
circuit. I touched one of the conductor wires and got a shock, nothing
more than a mild tingle. Is the RCBO able to prevent a significant
electric shock? I will *not* be recommending or repeating this.

Always confirm a circuit is dead. Easiest way is with a non-contact
sensor. First check the sensor is working using a known live
somethingorother, then check your circuit is dead, then re-check your
sensor is still working on a live wire.

When i used to work at Pye Television transmitters we had a three phase
transformer that used to wind up the 415 volt AC mains to around 15 kV
for the high voltage Klystron supplies we were supplying these units to
Korea IIRC.
Anyway one of the Korean men showed us how to check the 15 kV supply was
off, he just banged the earthing stick across the incoming mains on the
transformer.
Bloody great bang and flash and the whole factory went out, he was shall
we say shaken and stirred!...

When I worked at a supplier of large, industrial compressors, we had one
on the test stand, with a 3.5MW, 11kV, 3-phase motor. The Electrical
Engineer in charge of test supplies fired in the local breaker -
unfortunately, he'd not told anyone else and people were working on the
unit. Luckily no-one was hurt, but as the motor still had a set of
earthing bars across its inputs, there was a large bang, a flash, smoke
and the local breaker fired straight back out ... as did the one in the
distribution room; the one in the electricity board's end of the
distribution room; the one in the sub-station; the one feeding that
substation; and, IIRC, the one feeding the supplies further up the
chain. The factory, offices, dozens of other businesses and the local
council estate (around 14,000 homes) were blacked out and it took 3
hours before supplies were restored.

[Brian]

Post by Scott
It looks like I am in the hall of shame. To change a lightswitch, I
switched off the downstairs RCBO forgetting that the switch at the
bottom of the stairs was connected to a light fed from the upstairs
circuit. I touched one of the conductor wires and got a shock, nothing
more than a mild tingle. Is the RCBO able to prevent a significant
electric shock? I will *not* be recommending or repeating this.

No.

The trip current is way above that which can be fatal.

It is worth investing in a voltage detector of some kind- a meter or one of
those non-contact detectors you hold next to the cable.

[Max Demian]

Post by Scott
It looks like I am in the hall of shame. To change a lightswitch, I
switched off the downstairs RCBO forgetting that the switch at the
bottom of the stairs was connected to a light fed from the upstairs
circuit. I touched one of the conductor wires and got a shock, nothing
more than a mild tingle. Is the RCBO able to prevent a significant
electric shock? I will *not* be recommending or repeating this.

You need a neon screwdriver (if they are still available).

[SH]

Post by Max Demian

Post by Scott
It looks like I am in the hall of shame. To change a lightswitch, I
switched off the downstairs RCBO forgetting that the switch at the
bottom of the stairs was connected to a light fed from the upstairs
circuit. I touched one of the conductor wires and got a shock, nothing
more than a mild tingle. Is the RCBO able to prevent a significant
electric shock? I will *not* be recommending or repeating this.

You need a neon screwdriver (if they are still available).

https://worldpopulationreview.com/country-rankings/neon-production-by-country

[Andy Burns]

Post by SH

Post by Max Demian
You need a neon screwdriver (if they are still available).

https://worldpopulationreview.com/country-rankings/neon-production-by-
country

Ah, that little snag had passed me by ... Clive will be upset.

[Jeff Layman]

Post by Andy Burns

Post by SH

Post by Max Demian
You need a neon screwdriver (if they are still available).

https://worldpopulationreview.com/country-rankings/neon-production-by-
country

Ah, that little snag had passed me by ... Clive will be upset.

<https://www.toolstation.com/search?q=mains+tester+screwdriver&brand=Roughneck>
20+ available for delivery.

[brian]

Post by Scott
It looks like I am in the hall of shame. To change a lightswitch, I
switched off the downstairs RCBO forgetting that the switch at the
bottom of the stairs was connected to a light fed from the upstairs
circuit. I touched one of the conductor wires and got a shock, nothing
more than a mild tingle. Is the RCBO able to prevent a significant
electric shock? I will *not* be recommending or repeating this.

Not if you put your fingers across live and neutral like what I did
recently.

They only trip if you go between live and earth, or short neutral and
earth.

Brian

[The Natural Philosopher]

Post by brian

Post by Scott
It looks like I am in the hall of shame. To change a lightswitch, I
switched off the downstairs RCBO forgetting that the switch at the
bottom of the stairs was connected to a light fed from the upstairs
circuit. I touched one of the conductor wires and got a shock, nothing
more than a mild tingle. Is the RCBO able to prevent a significant
electric shock? I will *not* be recommending or repeating this.

Not if you put your fingers across live and neutral like what I did
recently.
They only trip if you go between live and earth,

Yes. T shirts are available :-)

Post by brian
or short neutral and
earth.

Sometimes...

BUT the key is that you are mostly earthed anyway and an RCD should trip
even if you are touching neutral as well.

Post by brian
Brian

--
“it should be clear by now to everyone that activist environmentalism
(or environmental activism) is becoming a general ideology about humans,
about their freedom, about the relationship between the individual and
the state, and about the manipulation of people under the guise of a
'noble' idea. It is not an honest pursuit of 'sustainable development,'
a matter of elementary environmental protection, or a search for
rational mechanisms designed to achieve a healthy environment. Yet
things do occur that make you shake your head and remind yourself that
you live neither in Joseph Stalin’s Communist era, nor in the Orwellian
utopia of 1984.”

Vaclav Klaus