RCD Randomly Tripping

[JohnW2]

I did eliminate the extractor John by removing the wires completely from the extractor and the RCD still tripped.

As I said, that's what I thought. Thanks for confirming.

The only things on the disconnected half of the circuit are the bathroom light and extractor with a bathroom pull switch and a landing light with a twin switch.

OK. Until your test equipment arrives, we are rather grasping at straws, but you could try removing all (sounds like only two) bulbs/lamps on that 'part circuit' (and also disconnect fan at its terminals). If you then still get trips, it would presumably be due to the wiring etc. in that part of the ring.

Kind Regards, John

 

[securespark]

That blue in the loop terminal is presumably a line to the switch. If so, there does not seem to be sleeving on it.

 

[AndrewCollis]

Hi Everyone

Just a small update.

I took the ceiling down in the bathroom and disconnected the rose completely. I put the landing rose back together again so the only light not working was the bathroom. I also connected all the wires at the cu. It was fine for 3 hours hours so I thought I would try something different. I disconnected one side of that circuit on the cu and connected the bathroom rose up with only the powered cable. It was fine for 40 minutes and then the RCD tripped. I swapped over the wires to the other in the rose and the cu and tried again.

I have also disconnected the bathroom light as John suggested and the extractor has no wiring in the rose so I hope this time it will not trip and I will have found the wire thats at fault.

All the best
Andrew

 

[securespark]

When you have found the culprit, you need to ensure one of two things:

Either you make access to the connections in the loft

Or else fit a maintenance-free JB.

 

[AndrewCollis]

Good Afternoon Everyone.

I just wanted to thank everyone for all your help. I have found the problem wire. After narrowing the fault down to the bathroom, it was easy to trace the problem to the wire from the landing rose to the bathroom rose. Physically I couldnt see anything wrong with the but it was making the RCD trip and now its replaced there are no more problems.

I really appreciate all the advice and have learned a lot in the process.

Good luck everyone and thanks again

All the best
Andrew

 

[EFLImpudence]

Well done. Thanks for letting us know.

You can test the bit of cable when your new toys arrive. Let us know.

 

[AndrewCollis]

Thanks EFLImpudence, I will.

All the best
Andrew

 

[JohnW2]

I have found the problem wire. After narrowing the fault down to the bathroom, it was easy to trace the problem to the wire from the landing rose to the bathroom rose. Physically I couldnt see anything wrong with the but it was making the RCD trip and now its replaced there are no more problems.

I'm glad that it's apparently 'sorted', but that (a spontaneously-occurring fault to earth in a cable which is apparently physically intact) has to be a pretty unusual fault. Like EFLI, I'll be interested to hear what your IR meter has to say about it, when it arrives!

Were there any very tight bends or kinks in the cable?

Kind Regards, John

 

[AndrewCollis]

Hi John

The cable had a lot of kinks, it was laid across the joists in the loft rather than along and through the joists. Looked like people had been treading on it a lot when they took the chimneys out. I couldnt see any piercings or cuts to the wire though (sorry my wording of couldnt see anything wrong with it was bad)

I am expecting my new toy to arrive on Saturday and am excited to learn how to use it and then will test everything.

All the best
Andrew

 

[JohnW2]

Hi John ... The cable had a lot of kinks, it was laid across the joists in the loft rather than along and through the joists. Looked like people had been treading on it a lot when they took the chimneys out. I couldnt see any piercings or cuts to the wire though

Impact can sometimes split the insulation of one of the conductors within. I once saw a T+E cable that someone (not me!) had accidentally hit hard with a hammer and, when we took it apart, that showed such a split - I think the bare earth wire can be 'pushed through' the insulation of one of the adjacent conductors as a result of such trauma. Heavy 'treading', particularly in the vicinity of a kink, might be enough to do that.

Hopefully, once you've got it and discovered how to use it (easy!), your IR meter will confirm a low reading - and then it's up to you as to whether you take the whole cable apart to discover exactly what has happened!

Does the taking out of the chimneys chronologically correspond roughly with when your RCD trips started?

Kind Regards, John

 

[securespark]

I had a 2.5 under a floor that I installed and it went faulty, tripping the RCD intermittently.

I chopped it out, and examined it closely. There was a pinhole in the cable sheath and insulation and that was all it took to allow damp to track across.

 

[Iggifer]

We pulled this cable in recently. Wonder why the RCD tripped......

 

[stillp]

I had a 5-metre length of T & E feeding a security light, installed by a pro while I was travelling for work, which had three L - E shorts in it. It was Turkish. Faults showed up after a few months' use. It was in the loft, not subject to any movement, and only supplied the 150W light.

 

[securespark]

We pulled this cable in recently. Wonder why the RCD tripped......
View attachment 104098 View attachment 104099

Wow!

Heard lots of stories at the wholesaler's counter about this but never encountered it!

 

[Iggifer]

As you can probably tell from the first picture, it was from a drum of SY.

The only visible sign through the clear layer was a TINY amount of talc. Not even really sure how it could have happened. The machine they use to extrude the cable must have jammed a bit. Friday afternoon perhaps?