RCD tripping!

[jrpatten]

A question to you electrical experts. One of the RCDs in our fuse box trips now and again, usually every couple weeks or so for no apparent reason. It does not trip when we turn something on, it just trips completely randomly. We initially thought it may be are old fridge, but we now have a new one and it still does it. I got an electrician in to test it, and he says that the RCD is tripping correctly at the correct loaf. He said the fuse box is the cheapest you can get, and that it would be worth changing it and the splitting it out differently with 3 RCDs as we have a second floor attic room. He also said some sockets are not double pole switched (would this make a difference?).

Anyway, Yesterday I plugged in my laptop on the first floor and the RCD tripped, however the strange thing is that the first floor sockets are not one of the MCBs connected to that particular RCD! It is connected to the RCD on the right. Does this sound strange? Also if I turn a good few devices on on the first floor and turn off the MCB, then turn it back on this can also trip the RCD.

 

[securespark]

Did the electrician test the IR?

It's no good just testing the RCD on its own.

 

[EFLImpudence]

One of the RCDs in our fuse box trips now and again, usually every couple weeks or so for no apparent reason. It does not trip when we turn something on, it just trips completely randomly.

Do you have exterior accessories, appliances or lighting which could be getting wet?

We initially thought it may be are old fridge, but we now have a new one and it still does it.

Not that then.

I got an electrician in to test it, and he says that the RCD is tripping correctly at the correct loaf.

Did he find the fault?

He said the fuse box is the cheapest you can get, and that it would be worth changing it

Except that the RCD was good and detecting a FAULT.
Did he mention what the fault may be?

and the splitting it out differently with 3 RCDs as we have a second floor attic room

Best thing would be to find the fault first.

He also said some sockets are not double pole switched (would this make a difference?).

Not to the RCD.

Anyway, Yesterday I plugged in my laptop on the first floor and the RCD tripped, however the strange thing is that the first floor sockets are not one of the MCBs connected to that particular RCD! It is connected to the RCD on the right. Does this sound strange?

Coincidence - if all the wiring is correct.

Also if I turn a good few devices on on the first floor and turn off the MCB, then turn it back on this can also trip the RCD.

Do you mean the 'other' RCD?

 

[jrpatten]

Thanks for your replies.

Interesting point about rain. I will monitor weather when it does trip. We have an outside plug, which is isolated inside and always switched off. Also two outside spot lights.

Not sure what an IR is, however he was testing lots of stuff on the fuse box and said everything seemed fine, and to try unplugging different things around the home as it seems like an appliance fault.

As for the RCD, we seem to have 8 MCBs, 4 connected to each RCD, and as I said in the last post, if I turn on lots of appliences on the first floor then turn off it's MCB, then flick it back on quickly it always trips the left RCD, but the first floor sockets are connected to the right RCD. Just seems a little strange to me.

 

[EFLImpudence]

Not sure what an IR is,

Insulation Resistance - tests the resistance between the conductors through the insulation.

however he was testing lots of stuff on the fuse box and said everything seemed fine, and to try unplugging different things around the home as it seems like an appliance fault.

Yes unplug, not enough to switch off at socket unless double pole (hence his comment) as there could be a fault between neutral and earth,

As for the RCD, we seem to have 8 MCBs, 4 connected to each RCD, and as I said in the last post, if I turn on lots of appliences on the first floor then turn off it's MCB, then flick it back on quickly it always trips the left RCD, but the first floor sockets are connected to the right RCD. Just seems a little strange to me.

It is. Can't think of anything (at the moment) that would cause that without causing it all the time.

 

[securespark]

One of the RCDs in our fuse box trips now and again, usually every couple weeks or so for no apparent reason. It does not trip when we turn something on, it just trips completely randomly.

I got an electrician in to test it, and he says that the RCD is tripping correctly at the correct loaf.

Did he find the fault?

No, 'cos he's a crummy spark.

No, 'cos the OP has not paid enough dough.

No, 'cos he's not well-bred.

No, 'cos he's a bit crusty.

 

[EFLImpudence]

Crumbs, I thought you were half baked until I twigged.

 

[Alarm]

I missed the LOAF bit at first lol

 

[17thman]

the best thing to do is to slice it up into invididual circuits

 

[Alarm]

If you BUTTER up your sparks he might do it cheaper.

 

[ericmark]

All RCD's are not the same. If one uses a X-Pole RCD which monitors leakage and does not trip until 95% of leakage current it will trip far less than the run of the mill cheap type.

I have had two RCD's fitted for many years. About 1992 I think both 30ma at 40ms and from time to time they do trip with no fault.

Thunder storms or any other spikes on the line can cause them to trip. And resetting one without first opening all the MCB's can cause the other one to trip.

The reason they trip is easy. Their cheap and nasty and I'm too tight to go out and buy some good quality ones. They do pass with a RCD tester and they do conform with British Standard but they are cheap and that's the problem.

If you want you can go for the real high quality type like this.

Untitled

• ericmark
• 6 Dec 2008
• 34

these will auto rest and even better than X-Pole but they cost. I think about £400 each.

Just got to face it you get what you pay for.