Switch ‘RCD Controlled Circuits’ tripping after new extension

[steveinoz01]

Hi

After a recent extension our fuse box trips out but I’m not sure why.

The switch that trips says ‘RCD Controlled Circuits’ but non of the other labelled switches trip so I can’t identify the problem area.

It only happens when we have a house full with two cookers in use, music playing, lights on etc. Last weekend we had a party and turning the kettle on in kitchen tripped the switch twice. The week before it was plugging in the laptop that caused the trip.

When the switch goes we lose downstairs lights, sockets and cookers.

Is it right that no other switch goes at the same time as this generic labelled ‘RCD Controlled Circuits’ switch? The electrician looked at the board the first time it happened and said he can’t find any problems but it’s now happened twice since.

I attach a picture of the fuse board and a close up of the switch.

Thanks.

 

[mwatsonxx]

turning the kettle on in kitchen tripped the switch twice. The week before it was plugging in the laptop that caused the trip.

I would guess something wrong with power circuit, when energised neutral in wrong neutral bar will cause a trip. Possibly faulty RCD, get your electrican to check both.

 

[333rocky333]

Having a summer house and a hot tub looks like you might have a few bob.
May be worth looking into having that board changed to all RCBOs, that way only the relevant circuit will go off rather than the inconvenience of half the house going off, not only now but also in the future.
The other switches are mcbs and work different, a majority of problems will likely trip the Rcd only

 

[EFLImpudence]

The two ovens would appear to be 'on' the other RCD (although it is labelled 'main switch').
They shouldn't affect the 'other' RCD so something is not right.

You need an electrician who knows what he is doing.

 

[JohnW2]

I would guess something wrong with power circuit, when energised neutral in wrong neutral bar will cause a trip.

It will, but in a far more consistent and 'inevitable' fashion than the OP is describing.

Possibly faulty RCD, get your electrican to check both.

Yes, having the RCD tested first is probably sensible, since if that is the problem, the cure is simple. If that's not the problem, then hunting down the cause(s) could be a bit of a nightmare, so it's best to look at the 'easy' possible cause first.

From what the OP says, it sounds as if it might be a case of accumulated small 'leaks' with extra loads with a small leak representing 'the last straw' - but I would be surprised if a kettle were that straw. Whatever, as you imply, I think it's a job for an electrician.

Kind Regards, John

 

[ban-all-sheds]

When the switch goes we lose downstairs lights, sockets and cookers.

Do you lose any circuits not on that RCD?

 

[steveinoz01]

Do you lose any circuits not on that RCD?

The only switch to trip is the one labelled ‘RCD Controlled Circuits’. I’ve not actually replicated the fault without a house full of people so haven’t had chance to see what actually is affected by this switch.

Is it right that the oven and kitchen sockets stop working even though their labelled switches on the board remain ‘on’ and it’s just the RCB switch that’s off?

 

[JohnW2]

Is it right that the oven and kitchen sockets stop working even though their labelled switches on the board remain ‘on’ and it’s just the RCB switch that’s off?

Yes, when that RCD trips it will kill all 6 circuits to the left of it, even though their individual breakers will remain 'on'.

Kind Regards, John

 

[EFLImpudence]

Am I mistaken in reading that two oven circuits are not on that RCD?

 

[JohnW2]

Am I mistaken in reading that two oven circuits are not on that RCD?

Ah! Whilst what I wrote is correct, as you say, neither of the oven circuits seem be amongst those "6 to the left" of the RCD which apparently trips.

That makes this all rather odd (given that the ovens usually work). It seems very hard to believe that the RCDs could be serving other than the set of circuits adjacent to them!

Kind Regards, John

 

[mwatsonxx]

Ah! Whilst what I wrote is correct, as you say, neither of the oven circuits seem be amongst those "6 to the left" of the RCD which apparently trips.

That makes this all rather odd (given that the ovens usually work). It seems very hard to believe that the RCDs could be serving other than the set of circuits adjacent to them!

Kind Regards, John

The usual descent into waffling nonsense has begun, good bye.

 

[John D v2.0]

Basically there a small or intermittent neutral to earth fault somewhere in your RCD protected side.
This means that when a heavy load is taken anywhere in your installation, some of the current returns to the cutout via the main earth terminal instead of the RCD. Then it trips due to the fault.
An electrician would be able to do an insulation resistance treat and find the issue

 

[JohnW2]

Basically there a small or intermittent neutral to earth fault somewhere in your RCD protected side. This means that when a heavy load is taken anywhere in your installation, some of the current returns to the cutout via the main earth terminal instead of the RCD. Then it trips due to the fault.

That's obviously the 'usual' situation.

However, can you explain how an L-E fault on one of the circuits protected by the RCD which trips could result in appliances (the ovens) losing power, even though they are on a different RCD (the second 'Main Switch' is actually another RCD), despite that other RCD and the oven circuits' MCBs not having tripped?

Kind REgards, John

 

[John D v2.0]

It was efli who brought the ovens into it, I assume the op meant Hobbs which are indeed on the same rcd. And the op doesn't realise that the RCD is in series with the MCBs, he thinks they are unrelated devices.

 

[JohnW2]

It was efli who brought the ovens into it ...

Well, it was the Op who mentioned it first ...

Is it right that the oven and kitchen sockets stop working even though their labelled switches on the board remain ‘on’ ...

... I assume the op meant Hobbs which are indeed on the same rcd.

Well, yes, your crystal ball could be right (it would certainly make more sense of the situation). I was merely going by what the OP had actually written

Kind Regards, John