Randomly tripping RCD

[LozP]

Looking for some advice with a randomly tripping RCD.
Last week I got up to find the electrics had tripped during the night. No individual switch had tripped, just the main one. By process of elimination I narrowed it down to the upstairs sockets.
I left them off and when I returned from work reset the switch and all was ok, for a couple of hours and then it tripped again. It has now tripped randomly over the last week with nothing at all plugged in and also when something has been plugged in but not switched on.
I’ve had no work done, obviously it hasn’t been raining, so I’m at a bit of a loss what to try next.
I have had a lot of renovation work done over the last few years causing a lot of dust but nothing in the last 12 months. I did have a similar issue a couple of years ago when the dog peed on a socket and it needed to dry out. I’ve asked the dog, he says it’s not him.
Is there any kind of equipment I could buy to test the sockets or do I need to call out an electrician? Any advice would be much appreciated.

 

[Taylortwocities]

RCDs will trip if there is an earth problem on the live, or the neutral conductor of a circuit. Unplugging everything may eliminate the plugged in items, but there will be other things connected, like outside power sockets and lights, boiler, heating pumps and valves etc that you cannot unplug. And there is the wiring itself. Any of those can cause an RCD to trip.

To track down this sort of fault you would need at least an Insulation Resistance Tester, and of course the knowledge of how to use it and how to interpret the readings. If you don't have either the right equipment or knowledge, then your best bet is to engage the services of an electrician.

 

[LozP]

Thank you, and yes I think it will end up being an electrician job.
Can these type of faults be intermittent though? I switched the upstairs sockets back on last Friday, and quite happily ran a fan, hair dryer, radio using the sockets all over the weekend and up til 8pm last night when they tripped again whilst nothing at all was plugged in or in use.
The outside socket is on a completely separate circuit as I had an extension built 5 years ago and it runs from that, as does the boiler. I am officially confused.com

 

[Taylortwocities]

This sort of thing is always a bit of detective investigation. Eventually it will be revealed and you'll say "of course".

Do report back when its discovered.

 

[securespark]

I’ve asked the dog, he says it’s not him.

They're often C.A.F., but NEVER believe a dog; they are out and out liars.

 

[Taylortwocities]

It’s the cat that did it (says my dog).

 

[securespark]

The outside socket is on a completely separate circuit

Not in the eyes of the RCD, if you have ONE RCD covering ALL the circuits.

 

[securespark]

It’s the cat that did it (says my dog).

They're not much better, the deceitful little buggers.

 

[LozP]

There is one main switch that covers the whole board and that’s what trips, but the single switch that if I switch off stops it tripping is upstairs sockets. Although some pillock labelled it downstairs sockets so that was fun to work out!
My cat is also blaming the dog, but he looks far too smug to be trustworthy

 

[LozP]

 

[EFLImpudence]

There is one main switch that covers the whole board and that’s what trips,

Do you really mean the "MAIN SWITCH for all circuits" is the one that trips?

but the single switch that if I switch off stops it tripping is upstairs sockets. Although some pillock labelled it downstairs sockets so that was fun to work out!

...but you haven't altered it yet, so...

 

[LozP]

It’s the one on the far right that goes and turns everything off. But if I leave the upstairs (written downstairs) sockets off it’s fine.
No I’ve not altered it yet, I kind of wore myself out running up and down the stairs lol.

 

[EFLImpudence]

That switch shouldn't turn of the lights or the other circuit (Possibly an immersion?).

If turning off the upstairs socket circuit really does stop the tripping - how long have you waited to find out? - then the fault is likely to be a Live to Earth leakage which could either be an appliance or the circuit itself.
If you cannot reproduce this fault at will then it will require some investigation with the proper equipment.

 

[LozP]

When it trips, if I try to switch the RCD back on it won’t stay, trips immediately. Leaving the sockets off let’s me turn it back on. But if I leave if for a few hours it will let me turn the sockets back on and then it can be anywhere between a couple of hours and several days before it goes again, with nothing at all plugged in or switched on. No immersion heater, there’s a combi boiler and no tanks.
It’s all very strange.

 

[crystal ball]

In these random tripping cases I suspect water ingress first, CH pump, leaky pipe onto JB, under sink socket getting drips, maybe dries out for a while then when family gets home drip drip, secondly elements, cooker, immersion