How to find where cable fault is?

[Agile]

Sorry, yes the 6mm will presumably be stranded which would be very unlikely to fail by breaking.

However over the 10m of concealed cable run there could well be some kind of connector or joint which has failed.

 

[securespark]

It's just a case of tracing the entire length.

 

[plugwash]

If the fault is a dead short,then you can measure the resistance from both ends, and that may give you an idea of where the fault lies, doesn't help if it's an open circuit, or a high resistance shunt fault though.

There exist tools in the telecommunications and utility worlds for finding distances to faults, but I have never heard of a domestic electrician using them, and I don't know if they would have the resolution to be useful with the cable types and distances typical in a domestic installation.

 

[JohnW2]

Unless there is evidence of rodent activity!

That was one of my first thoughts, but ....

But I doubt they would get through the whole of a shower cable!

I agree - particularly since they generally seem to 'stop' nibbling (for one reason or another ( when they hit copper!

Kind Regards, John

 

[oldbutnotdead]

Think someone already suggested tone generator if its an open circuit fail...you could try hire shops for time domain reflectometer but (if the whole run is inaccessible anyway) you might as well get stuck into lifting laminate and floorboards. Bet there's a hidden JB or an old isolator that someone has buried

 

[JohnW2]

The supply to the rear bedroom has failed although it is leaving the CU in the basement.

Just to be clear ... are we certain that this supply has ever 'worked' (in the past) ?

Kind Regards, John

 

[Murdochcat]

There is a break in the live somewhere.

And no isolator in or near the shower.

How have you confirmed continuity of the neutral and CPC ?

 

[Agile]

Solved!

The owner found someone to come and look at it.

They discovered that there was an isolator switch a couple of meters before the shower unit and conveniently hidden behind the head board of the bed. That had been turned off by the tenant.

That greatly surprised me bacause the tenant is an Indian lady who is an expert on computers who has come to the UK to convert systems from using hard drives to use cloud storage. She seemed pretty switched on to me so I am surprised that she did not remember switching it off!

I was there for other things and while there the kitchen ring went off leaving the fridge freezer and hob unpowered. So i wanted to solve the problem. I discovered about 200mm of water in the basement as the auto pump had tripped its RCD but that reset and started pumping.

The kitchen ring had tripped the MCB and probably due to a faulty electric kettle. That reset okay.

 

[Deleted member 267285]

Solved!

The owner found someone to come and look at it.

They discovered that there was an isolator switch a couple of meters before the shower unit and conveniently hidden behind the head board of the bed. That had been turned off by the tenant.

That greatly surprised me bacause the tenant is an Indian lady who is an expert on computers who has come to the UK to convert systems from using hard drives to use cloud storage. She seemed pretty switched on to me so I am surprised that she did not remember switching it off!

I was there for other things and while there the kitchen ring went off leaving the fridge freezer and hob unpowered. So i wanted to solve the problem. I discovered about 200mm of water in the basement as the auto pump had tripped its RCD but that reset and started pumping.

The kitchen ring had tripped the MCB and probably due to a faulty electric kettle. That reset okay.

I might have known a sari was involved

 

[Murdochcat]

A suitable isolation switch would be double pole.

So no live or neutral on the end of the circuit

 

[Agile]

She does not wear a saree and may be clever but is very short indeed perhaps about 4' 10" but quite friendly.

 

[Agile]

Oddly nobody suggested using a CAT. I think they can detect a live cable at a fair distance.

I think that I have one somewhere so could have found it and checked it.

I think it uses large dry batteries so I have not been very enthusiastic about it. But as they sell for a high price I really ought to find it and convert it to rechargeable batteries and sell it.

 

[Harry Bloomfield]

Oddly nobody suggested using a CAT. I think they can detect a live cable at a fair distance.

I think that I have one somewhere so could have found it and checked it.

I think it uses large dry batteries so I have not been very enthusiastic about it. But as they sell for a high price I really ought to find it and convert it to rechargeable batteries and sell it.

BT used to use a smaller, more portable version, but it doesn't work over such larger distances. I paid £20 for it at a rally, two parts - the signal generator, and the detector which has adjustable sensitivity.

 

[Agile]

BT had several types.

The most common was a fairly short range yellow one which could detect a tone applied at the exchange within a cabinet at a distance of about 100mm.

But the nice one was one that could be held up in the air and detect a tone applied to overhead drop wires several meters above the user.