From Newsgroup: uk.d-i-y

On 20/02/2026 20:09, Cursitor Doom wrote:

Gentlemen,

I was in my workshop earlier today buggering around, when - with no provocation at all - the lights all went out. My lights are in 3
clusters, each with their own switch. I checked the breakers and sure
enough, the breaker for the lighting (which supplies these 3 clusters)
had thrown-out. So I thought I'd turn 'em all off, then switch them
back in one at a time to find out which cluster was causing the
problem. The first time I tried this, cluster 1 came on fine. Then I
turned on cluster 2 and that was fine, too. On switching in cluster 3, however, the breaker tripped again immediately. So I thought I'd
narrowed the fault down to cluster 3's circuit.
Anyway, to cut a long story short, when I repeated this test, with all
3 clusters switched off, it was impossible to reset the lighting
breaker; it just popped out immediately, even with none of the lights switched on. I'm just wondering if the fault therefore might be in the breaker itself. Can they just 'go' like that with no warning? And if
so, what's the typical failure mode?

1. Let the breaker cool down
2. You may have a short

Cheers,

CD

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

On 20/02/2026 20:09, Cursitor Doom wrote:

Gentlemen,

I was in my workshop earlier today buggering around, when - with no provocation at all - the lights all went out. My lights are in 3
clusters, each with their own switch. I checked the breakers and sure
enough, the breaker for the lighting (which supplies these 3 clusters)
had thrown-out. So I thought I'd turn 'em all off, then switch them
back in one at a time to find out which cluster was causing the
problem. The first time I tried this, cluster 1 came on fine. Then I
turned on cluster 2 and that was fine, too. On switching in cluster 3, however, the breaker tripped again immediately. So I thought I'd
narrowed the fault down to cluster 3's circuit.
Anyway, to cut a long story short, when I repeated this test, with all
3 clusters switched off, it was impossible to reset the lighting
breaker; it just popped out immediately, even with none of the lights switched on. I'm just wondering if the fault therefore might be in the breaker itself. Can they just 'go' like that with no warning? And if
so, what's the typical failure mode?

For clarification, the "breaker" in question, are we talking about a
MCB, RCD or RCBO?

What kind of lights are they (i.e. LED, Flu tube etc)?
--
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

On Sat, 21 Feb 2026 11:47:21 +0000, John Rumm
<see.my.signature@nowhere.null> wrote:

On 20/02/2026 20:09, Cursitor Doom wrote:

Gentlemen,

I was in my workshop earlier today buggering around, when - with no
provocation at all - the lights all went out. My lights are in 3
clusters, each with their own switch. I checked the breakers and sure
enough, the breaker for the lighting (which supplies these 3 clusters)
had thrown-out. So I thought I'd turn 'em all off, then switch them
back in one at a time to find out which cluster was causing the
problem. The first time I tried this, cluster 1 came on fine. Then I
turned on cluster 2 and that was fine, too. On switching in cluster 3,
however, the breaker tripped again immediately. So I thought I'd
narrowed the fault down to cluster 3's circuit.
Anyway, to cut a long story short, when I repeated this test, with all
3 clusters switched off, it was impossible to reset the lighting
breaker; it just popped out immediately, even with none of the lights
switched on. I'm just wondering if the fault therefore might be in the
breaker itself. Can they just 'go' like that with no warning? And if
so, what's the typical failure mode?

For clarification, the "breaker" in question, are we talking about a
MCB, RCD or RCBO?

What kind of lights are they (i.e. LED, Flu tube etc)?

They're all LED types so low current. These are just regular
over-current breakers, not GFI or anything like that.
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From Newsgroup: uk.d-i-y

On 21/02/2026 13:37, Cursitor Doom wrote:

On Sat, 21 Feb 2026 11:47:21 +0000, John Rumm
<see.my.signature@nowhere.null> wrote:

On 20/02/2026 20:09, Cursitor Doom wrote:

Gentlemen,

I was in my workshop earlier today buggering around, when - with no
provocation at all - the lights all went out. My lights are in 3
clusters, each with their own switch. I checked the breakers and sure
enough, the breaker for the lighting (which supplies these 3 clusters)
had thrown-out. So I thought I'd turn 'em all off, then switch them
back in one at a time to find out which cluster was causing the
problem. The first time I tried this, cluster 1 came on fine. Then I
turned on cluster 2 and that was fine, too. On switching in cluster 3,
however, the breaker tripped again immediately. So I thought I'd
narrowed the fault down to cluster 3's circuit.
Anyway, to cut a long story short, when I repeated this test, with all
3 clusters switched off, it was impossible to reset the lighting
breaker; it just popped out immediately, even with none of the lights
switched on. I'm just wondering if the fault therefore might be in the
breaker itself. Can they just 'go' like that with no warning? And if
so, what's the typical failure mode?

For clarification, the "breaker" in question, are we talking about a
MCB, RCD or RCBO?

What kind of lights are they (i.e. LED, Flu tube etc)?

They're all LED types so low current. These are just regular
over-current breakers, not GFI or anything like that.

Ah. so no 'cold filament' inrush

Something is seriously weird.

Mice ate your cables?
--
"Anyone who believes that the laws of physics are mere social
conventions is invited to try transgressing those conventions from the
windows of my apartment. (I live on the twenty-first floor.) "

Alan Sokal

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From Newsgroup: uk.d-i-y

On 21/02/2026 21:23, Cursitor Doom wrote:

On Sat, 21 Feb 2026 13:56:06 +0000, The Natural Philosopher <tnp@invalid.invalid> wrote:

On 21/02/2026 13:37, Cursitor Doom wrote:

On Sat, 21 Feb 2026 11:47:21 +0000, John Rumm
<see.my.signature@nowhere.null> wrote:

On 20/02/2026 20:09, Cursitor Doom wrote:

Gentlemen,

I was in my workshop earlier today buggering around, when - with no
provocation at all - the lights all went out. My lights are in 3
clusters, each with their own switch. I checked the breakers and sure >>>>> enough, the breaker for the lighting (which supplies these 3 clusters) >>>>> had thrown-out. So I thought I'd turn 'em all off, then switch them
back in one at a time to find out which cluster was causing the
problem. The first time I tried this, cluster 1 came on fine. Then I >>>>> turned on cluster 2 and that was fine, too. On switching in cluster 3, >>>>> however, the breaker tripped again immediately. So I thought I'd
narrowed the fault down to cluster 3's circuit.
Anyway, to cut a long story short, when I repeated this test, with all >>>>> 3 clusters switched off, it was impossible to reset the lighting
breaker; it just popped out immediately, even with none of the lights >>>>> switched on. I'm just wondering if the fault therefore might be in the >>>>> breaker itself. Can they just 'go' like that with no warning? And if >>>>> so, what's the typical failure mode?

For clarification, the "breaker" in question, are we talking about a
MCB, RCD or RCBO?

What kind of lights are they (i.e. LED, Flu tube etc)?

They're all LED types so low current. These are just regular
over-current breakers, not GFI or anything like that.

Ah. so no 'cold filament' inrush

Something is seriously weird.

Mice ate your cables?

Rats maybe. Either that or it's the breaker that's gone AWOL.
Pre-switchgear so must be breaker or cable.

It's not guaranteed to be pre switchgear. A short on cluster 3 could
have welded the lightswitch contacts closed. You need to disconnect the
load side from the lightswitch
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From Newsgroup: uk.d-i-y

On 21/02/2026 21:23, Cursitor Doom wrote:

They're all LED types so low current. These are just regular
over-current breakers, not GFI or anything like that.

Ah. so no 'cold filament' inrush

Something is seriously weird.

Mice ate your cables?

Rats maybe. Either that or it's the breaker that's gone AWOL.
Pre-switchgear so must be breaker or cable.

Well breaker failure is not unknown. Nor are rats

If you have the gear, disconnecting the mains from the circuit and using
a megger or even ohmeter might bring something up
--
There is something fascinating about science. One gets such wholesale
returns of conjecture out of such a trifling investment of fact.

Mark Twain

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