So, the kitchen lights tripped. OK, it must be another of those
LED downlights blown, I'll reset and see what is out. No, still
trips.

Remove all eight lights, still trips. OK, must be the movement
detector, let's disconnect that, and link the feed through. Still
tripping.

That's not good. Check for a L-N short at the fittings. Oh yes.

Looks like today's task is to see what I can find under the
bathroom floor. I need to split the wiring to see which way the
fault moves.

I am hoping it is something I can reach, not buried cables. My
guess is that it must be one of the (mains) light fitting
connectors, though it seems a bit strange. Maybe one of the
lights did fail, and the resultant disturbance has damaged
something.

Chris
--
Chris J Dixon Nottingham UK


Plant amazing Acers.

Chris J Dixon wrote:

So, the kitchen lights tripped. OK, it must be another of those
LED downlights blown, I'll reset and see what is out. No, still
trips.

Remove all eight lights, still trips. OK, must be the movement
detector, let's disconnect that, and link the feed through. Still
tripping.

That's not good. Check for a L-N short at the fittings. Oh yes.

Looks like today's task is to see what I can find under the
bathroom floor. I need to split the wiring to see which way the
fault moves.

I am hoping it is something I can reach, not buried cables. My
guess is that it must be one of the (mains) light fitting
connectors, though it seems a bit strange. Maybe one of the
lights did fail, and the resultant disturbance has damaged
something.

Well, it looks like I have found it. The first place I broke the
circuit put me straight on the problem. A length of cable - PVC
lighting cable about 12 years old - had failed live to earth in
the middle of a run. No external signs at all, not in a location
that would have experienced any unusual conditions. In the
ceiling, not near anything else.

I can only guess that a transient of some form created an unusual
overvoltage.

Here's hoping it was the fault, not a symptom.

Chris
--
Chris J Dixon Nottingham UK


Plant amazing Acers.

In article ,
Chris J Dixon wrote:
Well, it looks like I have found it. The first place I broke the
circuit put me straight on the problem. A length of cable - PVC
lighting cable about 12 years old - had failed live to earth in
the middle of a run. No external signs at all, not in a location
that would have experienced any unusual conditions. In the
ceiling, not near anything else.

Be interesting to remove it and strip it out to see the actual failure.
I'd guess more likely to be a manufacturing fault as it shouldn't have got
hot enough to melt, etc.

--
*Experience is something you don't get until just after you need it.*

Dave Plowman London SW
To e-mail, change noise into sound.

On Mon, 22 Oct 2018 10:56:49 +0100, Chris J Dixon wrote:

Chris J Dixon wrote:

So, the kitchen lights tripped. OK, it must be another of those LED
downlights blown, I'll reset and see what is out. No, still trips.

Remove all eight lights, still trips. OK, must be the movement detector,
let's disconnect that, and link the feed through. Still tripping.

That's not good. Check for a L-N short at the fittings. Oh yes.

Looks like today's task is to see what I can find under the bathroom
floor. I need to split the wiring to see which way the fault moves.

I am hoping it is something I can reach, not buried cables. My guess is
that it must be one of the (mains) light fitting connectors, though it
seems a bit strange. Maybe one of the lights did fail, and the resultant
disturbance has damaged something.

Well, it looks like I have found it. The first place I broke the circuit
put me straight on the problem. A length of cable - PVC lighting cable
about 12 years old - had failed live to earth in the middle of a run. No
external signs at all, not in a location that would have experienced any
unusual conditions. In the ceiling, not near anything else.

I can only guess that a transient of some form created an unusual
overvoltage.

Here's hoping it was the fault, not a symptom.

Chris

Could be a dodgy run of cable, although IIRC most of that was many years
ago.

When we knocked the house about we had to replace some runs of cable which
were oozing green stuff. Some sort of reaction between the copper and the
sheathing.

Cheers



Dave R


--
AMD FX-6300 in GA-990X-Gaming SLI-CF running Windows 7 Pro x64

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On Monday, 22 October 2018 10:56:51 UTC+1, Chris J Dixon wrote:
Chris J Dixon wrote:

So, the kitchen lights tripped. OK, it must be another of those
LED downlights blown, I'll reset and see what is out. No, still
trips.

Remove all eight lights, still trips. OK, must be the movement
detector, let's disconnect that, and link the feed through. Still
tripping.

That's not good. Check for a L-N short at the fittings. Oh yes.

Looks like today's task is to see what I can find under the
bathroom floor. I need to split the wiring to see which way the
fault moves.

I am hoping it is something I can reach, not buried cables. My
guess is that it must be one of the (mains) light fitting
connectors, though it seems a bit strange. Maybe one of the
lights did fail, and the resultant disturbance has damaged
something.

Well, it looks like I have found it. The first place I broke the
circuit put me straight on the problem. A length of cable - PVC
lighting cable about 12 years old - had failed live to earth in
the middle of a run. No external signs at all, not in a location
that would have experienced any unusual conditions. In the
ceiling, not near anything else.

I can only guess that a transient of some form created an unusual
overvoltage.

very unlikely.

Dave Plowman (News) wrote:

Be interesting to remove it and strip it out to see the actual failure.
I'd guess more likely to be a manufacturing fault as it shouldn't have got
hot enough to melt, etc.

This is what I found:

http://i63.tinypic.com/og9clz.jpg

Looks like the fault actually severed the earth conductor.

The movement detector is no longer functional, though I don't
suppose I will know if that was cause or effect.

Chris
--
Chris J Dixon Nottingham UK


Plant amazing Acers.

I remember some time ago having a break in a cable made from stranded two
core flex, that what it looked like was that the wire strands were not
continuous and the whole thing was made out of about 1ft strands overlapped
out of synch, so to speak to appear to be a continuous run, but at the fault
site it was as if some of the strands were short or broken leving very few
to connect to each other inside the sleeving or as if it had been stretched
pre manufacture. There was the problem. Over time it just stopped
conducting. Now on the one mentioned maybe its thinner part got so warm as
to melt the pvc or something inside.
Seems a little worrying that if it is the case.
We trust people to make cables that are in fact continuous, some are, it
seems not!

Brian

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"Dave Plowman (News)" wrote in message
...
In article ,
Chris J Dixon wrote:
Well, it looks like I have found it. The first place I broke the
circuit put me straight on the problem. A length of cable - PVC
lighting cable about 12 years old - had failed live to earth in
the middle of a run. No external signs at all, not in a location
that would have experienced any unusual conditions. In the
ceiling, not near anything else.

Be interesting to remove it and strip it out to see the actual failure.
I'd guess more likely to be a manufacturing fault as it shouldn't have got
hot enough to melt, etc.

--
*Experience is something you don't get until just after you need it.*

Dave Plowman London SW
To e-mail, change noise into sound.

Really? That is a little worrying. What would be the mechanism for such a
fault to be fast enough to do that, but not actually have the trip before it
did it, if you get my drift.

Switch mode psu on the motion detector?
Did it really have an earth?
Brian

--
----- --
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please
Note this Signature is meaningless.!
"Chris J Dixon" wrote in message
...
Dave Plowman (News) wrote:

Be interesting to remove it and strip it out to see the actual failure.
I'd guess more likely to be a manufacturing fault as it shouldn't have got
hot enough to melt, etc.

This is what I found:

http://i63.tinypic.com/og9clz.jpg

Looks like the fault actually severed the earth conductor.

The movement detector is no longer functional, though I don't
suppose I will know if that was cause or effect.

Chris
--
Chris J Dixon Nottingham UK


Plant amazing Acers.

In article ,
Chris J Dixon wrote:
Dave Plowman (News) wrote:

Be interesting to remove it and strip it out to see the actual failure.
I'd guess more likely to be a manufacturing fault as it shouldn't have got
hot enough to melt, etc.

This is what I found:

http://i63.tinypic.com/og9clz.jpg

Looks like the fault actually severed the earth conductor.

The movement detector is no longer functional, though I don't
suppose I will know if that was cause or effect.


Unless you have mixed up earths somewhere, a lighting circuit earth is
never going to carry enough current to do that? Any signs of a nail etc
having gone through it?

--
*Eagles may soar, but weasels don't get sucked into jet engines *

Dave Plowman London SW
To e-mail, change noise into sound.

On Monday, 22 October 2018 14:42:29 UTC+1, Chris J Dixon wrote:
Dave Plowman (News) wrote:

Be interesting to remove it and strip it out to see the actual failure.
I'd guess more likely to be a manufacturing fault as it shouldn't have got
hot enough to melt, etc.

This is what I found:

http://i63.tinypic.com/og9clz.jpg

Looks like the fault actually severed the earth conductor.

The movement detector is no longer functional, though I don't
suppose I will know if that was cause or effect.

Chris
--
Chris J Dixon Nottingham UK


Plant amazing Acers.

Several decades ago, there was a big flap over a batch of faulty cable that got out. Could be some of that. Can't remember the size and manufacturer.

On Monday, 22 October 2018 17:05:55 UTC+1, Dave Plowman (News) wrote:
In article ,
Chris J Dixon wrote:
Dave Plowman (News) wrote:

Be interesting to remove it and strip it out to see the actual failure.
I'd guess more likely to be a manufacturing fault as it shouldn't have got
hot enough to melt, etc.

This is what I found:

http://i63.tinypic.com/og9clz.jpg

Looks like the fault actually severed the earth conductor.

The movement detector is no longer functional, though I don't
suppose I will know if that was cause or effect.


Unless you have mixed up earths somewhere, a lighting circuit earth is
never going to carry enough current to do that? Any signs of a nail etc
having gone through it?

and to do that the CPC would need to be both carrying live current AND there to be a short. If wired & fused correctly that would not happen. And since that spot is burnt while the rest is not, there must have been a cable fault at that point too.

Someone will check that, I'm real tired.


NT

On 22/10/2018 14:42, Chris J Dixon wrote:

This is what I found:

http://i63.tinypic.com/og9clz.jpg

Looks like the fault actually severed the earth conductor.

To the left hand side I can see what looks like a split in the brown
sheathing.

Either the cable was faulty or it has been damaged during installation.


--
Adam

In article ,
says...


Could be a dodgy run of cable,

I was in the shop one day, many years ago when an irate
customer was complaining about a length of aerial cabe he'd
bought. He'd installed his aerial and the cable and it didn't
work.

In the middle of the cable, there was a strange lumpy bit
several inches long. When the sheath was slit open, it
revealed two bits of coax joined together with a piece of
string!



--

Terry

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