Kitchen Electrics Tripping Even After Everything Unplugged?

[bernardgreen]

Going back to Bernard green's example , how/why does the current on the neutral from the cooker divide at the CU ?

The current coming back on the Neutral from the load divides because there are two route from the Neutral bus bar to the Neutral conductor where it comes to the house. One is the intended route through the RCD sesor coil and the other route is via the fault ( Neutral to Earth ) which bypasses the RCD sensor.

Current will always take any available route, how much goes one way and how much goes the other way depends on the impedances of the two routes.

In the case of a failed heating element then some current leaks from the Live to the case of the element and thus to earth and does not return on the Neutral. Thus the currents on Live and Neutral are not equal in the RCD's sensor so the RCD trips OFF

 

[Gorguruga]

I've turned off the 4 wall fuses at the switches. Should I remove the actual 13A fuses completely from the plastic housing and then test for the RCD trip again?

Removed 4 fuses - 3 of them were 13A, the boiler one was 3A. Tried the fusebox again and it still trips.

Most if not all fuse connection units are double pole, removing the fuse would not make difference providing you have isolated the unit.
If all loads are now disconnected it sounds like a hard wire/accessory issue.
The next step I would take to eliminate/establish where the fault lies, would be to one by one remove the neutral of each circuit that is protected by the tripping RCD, until the RCD no longer trips. This should then flag up the circuit that is causing the issue. It maybe wise to employ an electrically skilled person at this point!

I got an electrician around last night and the problem is temporarily fixed. Although it's not entirely above board apparently as now the two wall sockets near the door are out of action. He said it could be a fire risk if too many sockets are used at the same time in it's current condition and that's it's not actually legal!

Also said it might have been something that chewed through the wire running inside the wall. Luckily that wire is easily accessible along the same plasterboard wall as the fusebox so it should be a fairly straight forward job according to the electrician, half hour, but all in all going to be quite expensive for both visits combined which is what I was hoping to avoid as the boiler repair cost an arm and a leg last month but you win some you lose some.

 

[PrenticeBoyofDerry]

I got an electrician around last night and the problem is temporarily fixed. Although it's not entirely above board apparently as now the two wall sockets near the door are out of action. He said it could be a fire risk if too many sockets are used at the same time in it's current condition and that's it's not actually legal!

And did the electrician elaborate on why?

Also said it might have been something that chewed through the wire running inside the wall.

Ah well that could be the cause, cheeky little buggers!

 

[Gorguruga]

I got an electrician around last night and the problem is temporarily fixed. Although it's not entirely above board apparently as now the two wall sockets near the door are out of action. He said it could be a fire risk if too many sockets are used at the same time in it's current condition and that's it's not actually legal!

And did the electrician elaborate on why?

Also said it might have been something that chewed through the wire running inside the wall.

Ah well that could be the cause, cheeky little buggers!

He mentioned something about the completion of the "ring circuit" and that in it's current state it's not stable. Said he wanted to lower the amps to 20 but didn't have the equipment so had to leave it at 32. Advised only to use a few sockets at a time, maximum, otherwise it could cause some sort of overload and be a potential fire hazard. Not too comforting all in all but I'm going to tape up all the plug sockets except 2, just to make sure the housemates remember!

 

[PrenticeBoyofDerry]

Sound like the ring final circuit is incomplete, was this down to intervention of the rodents feasting? Or is it different circuit?

 

[Gorguruga]

It was the rodents apparently, but he was just guessing because he didn't actually remove the wire and see any bite marks on there as yet. This is what it says on the receipt:

"Callout, faulty ring circuit, x1 leg of ring faulty, needs to be put right on next visit."

 

[DaveHerns]

Do you not think that was the real fault?

This fault only occurred midway through the warm up cycle and sometimes they could reset the RCD and the oven would work. As it was a temperature dependant fault there was no realistic way to check the element so we put a new one in having ascertained it was "probably" the fault. There are 2 other elements in this oven but this was the main one and as all is now OK I think we've solved it. I'll try to get a photo of how their Polish kitchen fitter (basically just a tiler) had connected the cooker to the supply as I think it may win a prize for best bodge

 

[ban-all-sheds]

Most if not all fuse connection units are double pole, removing the fuse would not make difference providing you have isolated the unit.

Even if SP switched, removing the fuse would make no difference, assuming it's properly wired.

 

[PrenticeBoyofDerry]

Most if not all fuse connection units are double pole, removing the fuse would not make difference providing you have isolated the unit.

Even if SP switched, removing the fuse would make no difference, assuming it's properly wired.

TBH, I don't recall ever coming across a SP/FCU but if they do exist? What you state is true!

 

[stillp]

Do you know of anything else I could do to try to isolate the fault?

It sounds like you have done everything that can be done without some knowledge and an Insulation Resistance tester.

Do go round the house one more time and check you have not forgotten something. It is easy to do.

Let me tell you a personal story:

I recently spent a whole day trying to find why my RCD was tripping - I am undergoing a large refurb of the kitchen at the moment, so I have been doing a LOT of additional wiring.

After a long tiring Saturday trying to plasterboard the kitchen ceiling, I slid into the bath, sipped a cool lager and the electrics tripped. I did everything that I advise on this forum. Unplugged everything on the faulty (ring final circuit), turned off all DP switches. I did it all. Got out my IR tester, split the ring and found an earth - neutral fault on one part of the circuit. It's now 2am, bed time.

Woke up on Sunday. Took down all of my new plasterboard in the kitchen ceiling, tested and checked all of my new cabling. It all checked out.
Started working my way round the ring final, one socket at a time. Still could not find the problem. Was it a screw? Conductor touching a pipe???

Frustrated, just before bedtime on Sunday (and looking forward to another day fault hunting on Monday) I had a shower. Taking my towel from the towel rail I noticed the one thing that I had forgotten about - the electric element in the dual fuel towel rail. I had forgotten all about it, and this is my own house!
The element had failed. I clicked off the FCU, reconnected and tested the ring and it was all working nicely again.

So, it was co-incidence that the element had failed at the same time as work was being carried out. But co-incidence does lead you down a long winding path into the distance.

So check, check and check again.

But it does sound like you need a competent electrician.

I'm distraught. Just found out my idol has feet of clay.

 

[Taylortwocities]

 

[Gorguruga]

Quick update: The electrician came around for the second visit to compete the wiring but unfortunately one of the sockets had the damp in the surrounding plasterboard so he removed the socket completely. There's now a hole in the wall (covered partially by the back plate of the old socket). So I've lost one socket as things stand, he said it's not worth wiring it up because it might go again in a few weeks, which is understandable.

He recommended that I use a foam filler in the hole, get some new plasterboard and just repair the wall and lose the socket completely. What do you think?

 

[bernardgreen]

What did he do with the cable(s) that were connected to the back of the socket he removed ?

 

[DaveHerns]

You need to fix the damp problem or your wall will crumble

 

[Gorguruga]

What did he do with the cable(s) that were connected to the back of the socket he removed ?

He said he disconnected them from the fusebox which is only about a meter away along the same wall.