From Newsgroup: uk.d-i-y

I went to turn my garage lights on and found that the power to the
garage had gone.

Checked the fusebox and one MCB and the RCD in the main consumer
unit had tripped. Now the RCD won't reset even with every circuit
turned off.

RCD fault? (In addition to whatever tripped the garage circuit).

Tim
--
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From Newsgroup: uk.d-i-y

tim+ wrote:

I went to turn my garage lights on and found that the power to the
garage had gone.

Checked the fusebox and one MCB and the RCD in the main consumer
unit had tripped. Now the RCD won't reset even with every circuit
turned off.

RCD fault? (In addition to whatever tripped the garage circuit).

Tim

What happens if you disconnect the output of the RCD?
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From Newsgroup: uk.d-i-y

tim+ <timdownieuk@yahoo.co.uk> wrote:

I went to turn my garage lights on and found that the power to the
garage had gone.

Checked the fusebox and one MCB and the RCD in the main consumer
unit had tripped. Now the RCD won't reset even with every circuit
turned off.

RCD fault? (In addition to whatever tripped the garage circuit).

Leakage between neutral and earth. Typically your MCB is single pole and interrupting the live but not the neutral. Try disconnecting the neutrals
of each circuit one at a time until you find which is causing the trip.
(it may not be the garage)

Theo
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From Newsgroup: uk.d-i-y

On 28/08/2025 15:49, tim+ wrote:

I went to turn my garage lights on and found that the power to the
garage had gone.

Checked the fusebox and one MCB and the RCD in the main consumer
unit had tripped. Now the RCD won't reset even with every circuit
turned off.

RCD fault? (In addition to whatever tripped the garage circuit).

Unlikely. More likely you have a genuine earth to neutral short

Tim

--
rCLwhen things get difficult you just have to lierCY

rCo Jean Claud J|+ncker

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From Newsgroup: uk.d-i-y

In article <lei*O3blA@news.chiark.greenend.org.uk>, Theo <theom+news@chi ark.greenend.org.uk> scribeth thus

tim+ <timdownieuk@yahoo.co.uk> wrote:

I went to turn my garage lights on and found that the power to the
garage had gone.

Checked the fusebox and one MCB and the RCD in the main consumer
unit had tripped. Now the RCD won't reset even with every circuit
turned off.

RCD fault? (In addition to whatever tripped the garage circuit).

Leakage between neutral and earth. Typically your MCB is single pole and >interrupting the live but not the neutral. Try disconnecting the neutrals
of each circuit one at a time until you find which is causing the trip.
(it may not be the garage)

Theo

If it is neutral to earth it needs a bit of current to be flowing anyway
else it won't trip..
--
Tony Sayer


Man is least himself when he talks in his own person.

Give him a keyboard, and he will reveal himself.


--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: uk.d-i-y

On 28/08/2025 21:26, tony sayer wrote:

In article <lei*O3blA@news.chiark.greenend.org.uk>, Theo <theom+news@chi ark.greenend.org.uk> scribeth thus

tim+ <timdownieuk@yahoo.co.uk> wrote:

I went to turn my garage lights on and found that the power to the
garage had gone.

Checked the fusebox and one MCB and the RCD in the main consumer
unit had tripped. Now the RCD won't reset even with every circuit
turned off.

RCD fault? (In addition to whatever tripped the garage circuit).

Leakage between neutral and earth. Typically your MCB is single pole and
interrupting the live but not the neutral. Try disconnecting the neutrals >> of each circuit one at a time until you find which is causing the trip.
(it may not be the garage)

Theo

If it is neutral to earth it needs a bit of current to be flowing anyway
else it won't trip..

Although with TN-S that current could be in another property... (causing
a voltage rise on neutral WRT to earth).
--
Cheers,

John.

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

Theo <theom+news@chiark.greenend.org.uk> wrote:

tim+ <timdownieuk@yahoo.co.uk> wrote:

I went to turn my garage lights on and found that the power to the
garage had gone.

Checked the fusebox and one MCB and the RCD in the main consumer
unit had tripped. Now the RCD won't reset even with every circuit
turned off.

RCD fault? (In addition to whatever tripped the garage circuit).

Leakage between neutral and earth. Typically your MCB is single pole and interrupting the live but not the neutral. Try disconnecting the neutrals
of each circuit one at a time until you find which is causing the trip.
(it may not be the garage)

Theo

A bit if an update. I had to leave the house to run an errand and when I
got back about 25 minutes later, the RCD reset normally and everything is working again.

Not sure what to do now.


Tim
--
Please don't feed the trolls
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From Newsgroup: uk.d-i-y

Tim+ <timdownieuk@yahoo.co.youkay> wrote:

Theo <theom+news@chiark.greenend.org.uk> wrote:

tim+ <timdownieuk@yahoo.co.uk> wrote:

I went to turn my garage lights on and found that the power to the
garage had gone.

Checked the fusebox and one MCB and the RCD in the main consumer
unit had tripped. Now the RCD won't reset even with every circuit
turned off.

RCD fault? (In addition to whatever tripped the garage circuit).

Leakage between neutral and earth. Typically your MCB is single pole and interrupting the live but not the neutral. Try disconnecting the neutrals of each circuit one at a time until you find which is causing the trip.
(it may not be the garage)

Theo

A bit if an update. I had to leave the house to run an errand and when I
got back about 25 minutes later, the RCD reset normally and everything is working again.

RCDs do sometimes get 'nervous' in my experience and, after a rest, will reset.

I'd do nothing for the present to see if the problem recurs at all.
--
Chris Green
-+
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From Newsgroup: uk.d-i-y

On 28/08/2025 21:26, tony sayer wrote:

In article <lei*O3blA@news.chiark.greenend.org.uk>, Theo <theom+news@chi ark.greenend.org.uk> scribeth thus

tim+ <timdownieuk@yahoo.co.uk> wrote:

I went to turn my garage lights on and found that the power to the
garage had gone.

Checked the fusebox and one MCB and the RCD in the main consumer
unit had tripped. Now the RCD won't reset even with every circuit
turned off.

RCD fault? (In addition to whatever tripped the garage circuit).

Leakage between neutral and earth. Typically your MCB is single pole and
interrupting the live but not the neutral. Try disconnecting the neutrals >> of each circuit one at a time until you find which is causing the trip.
(it may not be the garage)

Theo

If it is neutral to earth it needs a bit of current to be flowing anyway
else it won't trip..

True, but that must be happening or the RCD wouldn't keep tripping
would it?
--
I would rather have questions that cannot be answered...
...than to have answers that cannot be questioned

Richard Feynman



--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: uk.d-i-y

On 28/08/2025 22:22, Tim+ wrote:

Theo <theom+news@chiark.greenend.org.uk> wrote:

tim+ <timdownieuk@yahoo.co.uk> wrote:

I went to turn my garage lights on and found that the power to the
garage had gone.

Checked the fusebox and one MCB and the RCD in the main consumer
unit had tripped. Now the RCD won't reset even with every circuit
turned off.

RCD fault? (In addition to whatever tripped the garage circuit).

Leakage between neutral and earth. Typically your MCB is single pole and
interrupting the live but not the neutral. Try disconnecting the neutrals >> of each circuit one at a time until you find which is causing the trip.
(it may not be the garage)

Theo

A bit if an update. I had to leave the house to run an errand and when I
got back about 25 minutes later, the RCD reset normally and everything is working again.

Not sure what to do now.

Ive seen that occasionally.

Try turning each appliance on until it pops again.

If its earth neutral short each circuit will need a load on to pop it Sonething like an electric drill works well - nice high startup current

Tim

--
I would rather have questions that cannot be answered...
...than to have answers that cannot be questioned

Richard Feynman



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From Newsgroup: uk.d-i-y

tony sayer <tony@bancom.co.uk> wrote:

In article <lei*O3blA@news.chiark.greenend.org.uk>, Theo <theom+news@chi ark.greenend.org.uk> scribeth thus

tim+ <timdownieuk@yahoo.co.uk> wrote:

I went to turn my garage lights on and found that the power to the
garage had gone.

Checked the fusebox and one MCB and the RCD in the main consumer
unit had tripped. Now the RCD won't reset even with every circuit
turned off.

RCD fault? (In addition to whatever tripped the garage circuit).

Leakage between neutral and earth. Typically your MCB is single pole and >interrupting the live but not the neutral. Try disconnecting the neutrals >of each circuit one at a time until you find which is causing the trip.
(it may not be the garage)

Theo

If it is neutral to earth it needs a bit of current to be flowing anyway
else it won't trip..

Yebbut you can still get that if the MCB to the circuit is turned off.

ie:

live - RCD - MCB for circuit 1 - light bulb - neutral for circuit 1 -
neutral busbar in CU - neutral for circuit 2 - neutral/earth leak - earth.

ie the leak is on circuit 2, but it doesn't need any power to be on the live side of circuit 2 to cause an RCD trip. Turning off MCB 1 doesn't tell you anything about the location of the fault.

If instead there was one RCBO per circuit then the RCBO for circuit 2 would have tripped, telling you where the fault was.

Theo
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From Newsgroup: uk.d-i-y

Chris Green <cl@isbd.net> wrote:

Tim+ <timdownieuk@yahoo.co.youkay> wrote:

Theo <theom+news@chiark.greenend.org.uk> wrote:

tim+ <timdownieuk@yahoo.co.uk> wrote:

I went to turn my garage lights on and found that the power to the
garage had gone.

Checked the fusebox and one MCB and the RCD in the main consumer
unit had tripped. Now the RCD won't reset even with every circuit
turned off.

RCD fault? (In addition to whatever tripped the garage circuit).

Leakage between neutral and earth. Typically your MCB is single pole and >>> interrupting the live but not the neutral. Try disconnecting the neutrals >>> of each circuit one at a time until you find which is causing the trip.
(it may not be the garage)

Theo

A bit if an update. I had to leave the house to run an errand and when I
got back about 25 minutes later, the RCD reset normally and everything is
working again.

RCDs do sometimes get 'nervous' in my experience and, after a rest, will reset.

I'd do nothing for the present to see if the problem recurs at all.

Sounds like the simplest approach for the meantime. ;-)

Tim
--
Please don't feed the trolls
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From Newsgroup: uk.d-i-y

On Thu, 28 Aug 2025 21:22:26 +0000, Tim+ wrote:

Theo <theom+news@chiark.greenend.org.uk> wrote:

tim+ <timdownieuk@yahoo.co.uk> wrote:

I went to turn my garage lights on and found that the power to the
garage had gone.

Checked the fusebox and one MCB and the RCD in the main consumer unit
had tripped. Now the RCD won't reset even with every circuit turned
off.

RCD fault? (In addition to whatever tripped the garage circuit).

Leakage between neutral and earth. Typically your MCB is single pole
and interrupting the live but not the neutral. Try disconnecting the
neutrals of each circuit one at a time until you find which is causing
the trip. (it may not be the garage)

Theo

A bit if an update. I had to leave the house to run an errand and when
I got back about 25 minutes later, the RCD reset normally and everything
is working again.

Not sure what to do now.

Some sort of capacitance at work ?
--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: uk.d-i-y

Jethro_uk <jethro_uk@hotmailbin.com> wrote:

On Thu, 28 Aug 2025 21:22:26 +0000, Tim+ wrote:

A bit if an update. I had to leave the house to run an errand and when
I got back about 25 minutes later, the RCD reset normally and everything
is working again.

Not sure what to do now.

Some sort of capacitance at work ?

Could be something on a timer or switch? eg immersion heater is on a timer, but it's only powered when the tank stat says the water is too cold. So
it'll only cause a trip during timed periods but also only when hot water
has been drained.

The next day it's cold so the boiler runs the central heating and heats the water, and the immersion doesn't fire so no trip. It'll only trip on warm
days when somebody also had a bath.

(you can construct similar scenarios for various other appliances)

Theo
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From Newsgroup: uk.d-i-y

On 29/08/2025 13:58, Theo wrote:

tony sayer <tony@bancom.co.uk> wrote:

In article <lei*O3blA@news.chiark.greenend.org.uk>, Theo <theom+news@chi
ark.greenend.org.uk> scribeth thus

tim+ <timdownieuk@yahoo.co.uk> wrote:

I went to turn my garage lights on and found that the power to the
garage had gone.

Checked the fusebox and one MCB and the RCD in the main consumer
unit had tripped. Now the RCD won't reset even with every circuit
turned off.

RCD fault? (In addition to whatever tripped the garage circuit).

Leakage between neutral and earth. Typically your MCB is single pole and >>> interrupting the live but not the neutral. Try disconnecting the neutrals >>> of each circuit one at a time until you find which is causing the trip.
(it may not be the garage)

Theo

If it is neutral to earth it needs a bit of current to be flowing anyway
else it won't trip..

Yebbut you can still get that if the MCB to the circuit is turned off.

How?

ie:

live - RCD - MCB for circuit 1 - light bulb - neutral for circuit 1 -
neutral busbar in CU - neutral for circuit 2 - neutral/earth leak - earth.

ie the leak is on circuit 2, but it doesn't need any power to be on the live side of circuit 2 to cause an RCD trip. Turning off MCB 1 doesn't tell you anything about the location of the fault.

If instead there was one RCBO per circuit then the RCBO for circuit 2 would have tripped, telling you where the fault was.

He said he turned off EVERTYHING and it still tripped

Theo

--
"When one man dies it's a tragedy. When thousands die it's statistics."

Josef Stalin


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From Newsgroup: uk.d-i-y

On 29/08/2025 17:49, Theo wrote:

Jethro_uk <jethro_uk@hotmailbin.com> wrote:

On Thu, 28 Aug 2025 21:22:26 +0000, Tim+ wrote:

A bit if an update. I had to leave the house to run an errand and when
I got back about 25 minutes later, the RCD reset normally and everything >>> is working again.

Not sure what to do now.

Some sort of capacitance at work ?

Could be something on a timer or switch? eg immersion heater is on a timer, but it's only powered when the tank stat says the water is too cold. So it'll only cause a trip during timed periods but also only when hot water
has been drained.

The next day it's cold so the boiler runs the central heating and heats the water, and the immersion doesn't fire so no trip. It'll only trip on warm days when somebody also had a bath.

(you can construct similar scenarios for various other appliances)

Theo

You can also construct scenarios where several items together will cause enough earth leakage, but one alone will not. That is particularly true
of an earth neutral short
--
How fortunate for governments that the people they administer don't think.

Adolf Hitler


--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: uk.d-i-y

The Natural Philosopher <tnp@invalid.invalid> wrote:

On 29/08/2025 13:58, Theo wrote:

live - RCD - MCB for circuit 1 - light bulb - neutral for circuit 1 - neutral busbar in CU - neutral for circuit 2 - neutral/earth leak - earth.

ie the leak is on circuit 2, but it doesn't need any power to be on the live
side of circuit 2 to cause an RCD trip. Turning off MCB 1 doesn't tell you anything about the location of the fault.

If instead there was one RCBO per circuit then the RCBO for circuit 2 would have tripped, telling you where the fault was.

He said he turned off EVERTYHING and it still tripped

Ah, I missed that. If every single MCB in the installation is off there
could still be a leakage path from neutral to earth but the current would
have to come from somewhere external, eg from a neighbour. I would be
checking the supply N-E impedance as it might suggest there isn't a good
bond between them.

If it is a TT supply, the neutral is only bonded to earth at the transformer
so there could be a decent voltage between N and the customer's earth rod.
If there was N-E leak downstream of the RCD that could cause a N-E current
to flow through the RCD and trip it.

Theo
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From Newsgroup: uk.d-i-y

Theo <theom+news@chiark.greenend.org.uk> wrote:

Ah, I missed that. If every single MCB in the installation is off there could still be a leakage path from neutral to earth but the current would have to come from somewhere external, eg from a neighbour. I would be checking the supply N-E impedance as it might suggest there isn't a good
bond between them.

If it is a TT supply, the neutral is only bonded to earth at the transformer so there could be a decent voltage between N and the customer's earth rod. If there was N-E leak downstream of the RCD that could cause a N-E current
to flow through the RCD and trip it.

Actually, TT could be the source of randomness too. If it's dry, the ground dries up and the earth impedance to the substation increases, meaning the N from the transformer floats higher above local earth. A higher voltage
means more current can flow into a N-E fault, perhaps enough to trip the
RCD.

Then it rains, and the ground gets wet. E impedance to the transformer decreases (ie the quality of the earth bond improves) and there's less potential difference between N and local E. That could reduce the current flowing into a local fault and could fail to trip the RCD.

Would need some measurements to tell if this is at all plausible...

Theo
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From Newsgroup: uk.d-i-y

In article <fu58ol-k35m.ln1@q957.zbmc.eu>, Chris Green <cl@isbd.net>
scribeth thus

Tim+ <timdownieuk@yahoo.co.youkay> wrote:

Theo <theom+news@chiark.greenend.org.uk> wrote:

tim+ <timdownieuk@yahoo.co.uk> wrote:

I went to turn my garage lights on and found that the power to the
garage had gone.

Checked the fusebox and one MCB and the RCD in the main consumer
unit had tripped. Now the RCD won't reset even with every circuit
turned off.

RCD fault? (In addition to whatever tripped the garage circuit).

Leakage between neutral and earth. Typically your MCB is single pole and >> > interrupting the live but not the neutral. Try disconnecting the neutrals >> > of each circuit one at a time until you find which is causing the trip.
(it may not be the garage)

Theo

A bit if an update. I had to leave the house to run an errand and when I
got back about 25 minutes later, the RCD reset normally and everything is
working again.

RCDs do sometimes get 'nervous' in my experience and, after a rest, will reset.

I'd do nothing for the present to see if the problem recurs at all.

Amusing nervous the RCD! Perhaps what is happening is that there is
possibly a degree of leakage thats residual, like the leakage of a PC
power unit caps in it on the incoming supply line. Had this at a local
radio station years ago would take a large rewire to make it better as
more staff stated up their PC's the leakage rose, and sometimes the
next PC online too much for the RCD who said "stuff that I'm off"!.

RCBO's wouldn't have helped that as there was only the one ring main in
use in the building, the owners flogged the licence and the building is
now a Pizza hut!..
--
Tony Sayer


Man is least himself when he talks in his own person.

Give him a keyboard, and he will reveal himself.


--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: uk.d-i-y

On 31/08/2025 13:39, tony sayer wrote:

Had this at a local
radio station years ago would take a large rewire to make it better as
more staff stated up their PC's the leakage rose, and sometimes the
next PC online too much for the RCD who said "stuff that I'm off"!.

RCBO's wouldn't have helped that as there was only the one ring main in
use in the building, the owners flogged the licence and the building is
now a Pizza hut!..

Had this at our office building years ago. 35PCs simply tripped a 60A
mains incoming if they all powered on at once, We had to turn them on
one at a time., We fiitted 100A eventually
--
You can get much farther with a kind word and a gun than you can with a
kind word alone.

Al Capone



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