2 rcd tripped twice for no reason

[mack10]

Sunday afternoon and 2 RCDS tripped and one would not come back on. check all appliances and sockets and could not find anything that would trip it again.
We have not done anything with the electric of late. They did trip again and went off again after about 10 mins with no obvious cause.

They have now been on again for 30 mins and we are now all guns blazing for dinner and all the lights are on. Can't figure out why they tripped. Any suggestion s would be appreciated.

Thanks

 

[pjcomp]

Usual culprits for random tripping are fridges/freezers and boilers (which work to their own on/off schedule) and outside lights or sockets which may have got wet in them. Depending on your electric supply such unexpected random trips can also be caused by outside influences coming in, rather than inside events going out - tends to happen with pole-mounted supplies rather than the underground ones.

If none of the above, all you can do for the moment is see if it happens again. If not, put it down to nuisance tripping, if it does the hunt has to start in earnest.

PJ

 

[mack10]

They have tripped again so I put the heating on to see if that would trip it again it didn't also thought it might be the washing machine but that is running now also and no trips.

There is an office block that is being converted to flats about 5 6 streets away
I notice they had started digging up electric cables on Friday could it be that ? But what would it only be 2 switches that trip ( upstairs sockets and kitchen sockets)

The heating switches must be on the upstairs sockets circuit as that goes off when it trips by they way, but appears not to be the reason it is tripping.

 

[JohnW2]

But what would it only be 2 switches that trip ( upstairs sockets and kitchen sockets) ...

You described the things which were tripping as RCDs, but it sounds as if they are probably actually MCBs or RCBOs. Are there 'test buttons' on them? If so, what does the writing on them say?

Kind Regards, John

 

[mack10]

Hi there,

Thanks for the reply. There are no test buttons only trip switches.
They say 32a and a brand name I presume WYLEX.
Thanks

John

 

[JohnW2]

Thanks for the reply. There are no test buttons only trip switches. They say 32a and a brand name I presume WYLEX.

In that case, they are MCBs (Minature Circuit Breakers). Unlike RCDs, there are not usually subject to 'nusiance trips'. MCBs should only trip if there is an overload or fault on the circuit concerned - and it's very odd that the ones for two totally different circuits should suddenly start tripping.

You said that no electrical work has been done recently. Have you acquired any new electrical appliances or suchlike recently?

Kind Regards, John

 

[mack10]

Only a dab radio which was plugged in but not switched on at the socket. I have now unplugged it and stopped the washing machine.
I did have a few problems with the dab radio not working until I messed around with the plug, it is one of those you slot in the three pin or the 2 pin euro. I think the contacts were not contacting on the plug . Anyway it was plugged in but not switched on at the socket.

Apart from that nothing is different from the last 7 years that I have lived here and it has tripped maybe once / twice before but only one MCB.


Thanks

 

[EFLImpudence]

I think we need to know which two circuits have tripped.

Can you explain or post a picture?

 

[JohnW2]

I think we need to know which two circuits have tripped. ... Can you explain or post a picture?

... 2 switches that trip ( upstairs sockets and kitchen sockets) ... The heating switches must be on the upstairs sockets circuit as that goes off when it trips by they way, but appears not to be the reason it is tripping.

It does seem very odd that MCBs on two totally different circuits should suddenly start tripping for no obvious reason.

Kind Regards, John

 

[EFLImpudence]

Oh, sorry, missed that.

As it's two socket circuits - rings I presume, what about crossed legs at the MCBs and a short circuit ?

It doesn't help with the fault but would explain the result.

 

[JohnW2]

Oh, sorry, missed that. As it's two socket circuits - rings I presume, what about crossed legs at the MCBs and a short circuit ? It doesn't help with the fault but would explain the result.

True - but, as you say, that doesn't explain the nature of the fault which is suddenly causing two 32A MCBs to operate (I assume the OP means more-or-less simultaneously) intermittently, even if the circuits are 'crossed' (something which even I have seen in my time!). At least IME, faults that cause MCBs to operate are not usually intermittent. Seems rather odd to me.

Kind Regards, John

 

[mack10]

Hi there,

It is the kitchen sockets and the upstairs sockets. They do trip at the same time. I have switched everything off, heating , washing machine and unplugged everything except the fridge and the baby monitor on that circuit.

I don't understand why all of a sudden it is doing this when it has been fine for years and nothing has really changed.

Please see photo.


Thanks

 

[JohnW2]

Please see photo.

Here is one of them:

Untitled

• mack10
• 29 Sep 2013
• 1

Kind Regards, John

 

[securespark]

Are these two breakers that trip adjacent to each other??

One circuit may have a genuine fault and the MCB may be getting hot and causing the other one to heat up and trip out even though there may be no failure on that MCB's circuit.

My educated guess is that the kitchen circuit got overloaded at Sunday lunch time (cooker / washer/ kettle/ ??) and tripped the adjacent breaker.

 

[mack10]

Thanks to all seems to be a weird one. It still tripped when everything was turned off and unplugged??? Apart from fridge and baby monitor upstairs.

I replace a bulb in the fridge that blew a while back on Friday so I've taken that out to see if it trips again. So far it hasn't.

I'm going to get someone to have a look at it.

Thanks for all you suggestions.