Intermittent trip on two rings

JohnN · Dec 2, 2011

Hi,

Firstly, I'm a end user with no real electrical knowledge so please bear with me as I try to explain in non-technical (read stupid!) terms.

I've a weird fault, the where the RCD trips out, I've sort of isolated it to either the main ring or the kitchen as either one or the other will be the last one I turn back on when it comes back on - but it could be either and may trip out straight away again.

To make things even more arkward this has happened in the past, but that was months ago - then one last night and one this morning, but as you can see (using the PC) its working now.

I have a friend whos part trained as a sparkie years ago but doesn't like working on other peoples houses so can't help out directly and has no kit, he suggested unplug everything and switch it back on, now of course this is sound advice but only really valid when its off.

So I guess I'm looking for what it might be.

Thanks.

John

skydog1 · Dec 2, 2011

could be a faulty appliance unplug everything turn rcd on and then plug the appliances in one at a time you may find a certain appliance like a toaster is causing it.

best wishes

JohnN · Dec 2, 2011

Cheers, I'll do that next time it pops.

When it happened months ago it was just the kitchen that went and I did wonder if it was the kettle, but I switched it on and once the power was up again and it still worked fine.

Bit of an odd one, but yeah next time it goes I'll unplug the lot and see what if anything makes it go, annoyingly as its working now with everything on (and more) that was on when it went this morning I suspect I'm not going to get to the bottom of this quickly

HandySparks · Dec 2, 2011

If you get a sparky in, he can measure the actual sensitivity of the RCD and do an insulation resistance check of the wiring. If he has a suitable current clamp, and depending on how crowded your consumer unit is, he may be able to measure the differential current in each of your final circuits and perhaps track it down that way.

If you say whereabouts you are, someone on here could get in touch.

JohnN · Dec 3, 2011

I'm in the Mansfield area, but money is tight so daft as it sounds I'm having to hold back until I really need to and I suspect that testing will either result it "its fine" which will probably set me back £100 right up to "tut, tut, the whole house needs rewiring" which would make me rock quietly in a corner!

Octopus · Dec 3, 2011

How old is the house?

JohnN · Dec 3, 2011

It was built around 1925, so 86 years old, sadly I've no idea if anything has been done except the consumer unit which was replaced about four years ago.

Octopus · Dec 3, 2011

Hum, when the CU was replaced were you given a electrical installation certificate showing all the tests and results?

JohnN · Dec 3, 2011

Aha, yes! (Took a bit of hunting to find it)

Looks like the sockets up, down, kitchen and cooker were tested.

Is there anything I need to look for?

Octopus · Dec 3, 2011

I'd start by looking at the IR readings.

You may simply have a faulty RCD and a competent person with the right test gear could tell you within a few minutes of arriving.

I wouldn't expect a £100 bill to ramp test a RCD

JohnN · Dec 3, 2011

When I read that I thought I'd be writing a big table, but all results for Phase/Neutral, Phase/Earth and Neutral/Earth were 299 and Phase/Phase were N/A.

It would be nice if it is just the RCD as I understand those aren't too expensive.

Octopus · Dec 3, 2011

If I were you I'd do a search on the competent persons website, for registered Part P electricans in your immediate area, and call thenm and ask them how much they would charge to come and do an initial RCD ramp test. Explain you have the CU changed a while back and the test schedule is available.

Good luck

malcolmsanford · Dec 3, 2011

John I think the bottom line to this is your going to have to bite the bullet and call someone in.

It would be impossible to ask a doctor to remove your tonsils over a forum and it is virtually impossible to fault find the same way.

As you posted your location is Mansfield I'm sure one of the lads would be more than happy to give you a good price for this, and be assured all members are honest in their dealings.