RCD tripping, can't identify the appliance

ThisIsWeird

I'd also call your insurance up and ask as a layman, "Power cut, and now CH is not working. I've tried everything a homeowner would be expected to try, but now't. Am I covered?"
What's the excess payable?

Green_hopeful

Quite specific but we had something similar at my in-laws and their kitchen supply also served the outhouses. They were sure it was the boiler but the electrician who came out traced it to the outhouse. 

battenburg88

Thanks for everyone's advice so far! At least I have a working fridge still and it isn't the depths of winter to not have a boiler.To answer a couple of posts from overnight/this morning 

- Yes, I had a go at turning everything off (the big red switch on the consumer unit) but sadly that didn't help.
- There is a little outdoor storeroom beyond the utility room which has a bulb holder in it. Its never been used and I would assume that if it works - i've never used it - it would be on the downstairs light circuit.
- There is no excess on my home emergency cover and I'm covered for repairs up to £1000. From experience that includes a fairly hefty call out fee that they don't make very clear, but re-reading the policy I think that, as someone has suggested, I have a loss of heating/hot water so it could be worth asking them. I'd be a bit less inclined to make any kind of claim on my main home insurance but as I far as I recall the home emergency doesn't impact my no claims.

- Here is a picture of the consumer unit. It was the switch on the right that actually tripped after the powercut. I then went through the process of switching on each of the smaller switches to the left and it was the one highlighted that they caused the RCD to go again, so its now in the off position.

silvercar

When we had trouble identifying a fault like this, it turned out to be a socket wire was in contact with a screw that holds the socket cover in place. Nothing obvious to indicate it was that socket and nothing was plugged in at the time.

ThisIsWeird

battenburg88 said:

Thanks for everyone's advice so far! At least I have a working fridge still and it isn't the depths of winter to not have a boiler.To answer a couple of posts from overnight/this morning
- Yes, I had a go at turning everything off (the big red switch on the consumer unit) but sadly that didn't help.
- There is a little outdoor storeroom beyond the utility room which has a bulb holder in it. Its never been used and I would assume that if it works - i've never used it - it would be on the downstairs light circuit.
- There is no excess on my home emergency cover and I'm covered for repairs up to £1000. From experience that includes a fairly hefty call out fee that they don't make very clear, but re-reading the policy I think that, as someone has suggested, I have a loss of heating/hot water so it could be worth asking them. I'd be a bit less inclined to make any kind of claim on my main home insurance but as I far as I recall the home emergency doesn't impact my no claims.
- Here is a picture of the consumer unit. It was the switch on the right that actually tripped after the powercut. I then went through the process of switching on each of the smaller switches to the left and it was the one highlighted that they caused the RCD to go again, so its now in the off position.

Ok, so these wee individual switches are MCBs, and protect against current 'overload', such as caused by short circuits, or adding too many powerful appliances to a circuit.
The switch that actually tripped is an RCD, a very sensitive safety device designed to detect even small leakages. 
You are saying that as soon as you try and reset the MCB, the RCD trips? 
(The yellow button is the test, and you reset by simply pushing the switch back up).

Chances are the issue is being caused by a device that contains electronics. They can be sensitive to power 'spikes' and surges, common when a power outage is retuned. Your boiler obviously has a PCB, and also usually a number of external controls. But, they should all be isolated by that single FSU, and it should be DP.

I can't think of any easy way to check each of these FSUs, other than to unscrew their front plates and check they are DP, but there remains the possibility that it's a device you are unaware is on that circuit!

I'd be inclined to at least call up your HEC and ask. If you have done everything that a homeowner/layman can be expected to do - and you have - then this is an 'emergency' as there's no heating and stuff. But ask to clarify the cover, and that you won't be charged.

GDB2222

As long as you are sure that you have disconnected everything on that circuit that you can disconnect, then you need an electrician as the problem is with part of the circuit that you can’t get at. At least, not without a screwdriver, which I think you are right not to be wielding. Of course it could be the boiler, but the boiler man won’t be able to test it without power. 

Strange coincidence with the power cut. 

battenburg88

ThisIsWeird, thanks for the explanation, really useful. 
I've phoned up the insurer and the call out is free to check the boiler as I haven't got heating/hot water. I tried to explain that i'm not sure that it is the boiler and perhaps they should send an electrician in the first instance, but I don't think the call centre is really set up for requests like that. So a boiler person it is.

GDB2222 said:

As long as you are sure that you have disconnected everything on that circuit that you can disconnect, then you need an electrician as the problem is with part of the circuit that you can’t get at. At least, not without a screwdriver, which I think you are right not to be wielding. Of course it could be the boiler, but the boiler man won’t be able to test it without power. 

Strange coincidence with the power cut. 

I do have a sneaking suspicion that they boiler person is going to turn up and shrug their shoulders because the boiler can't turn on so they can't test anything. I'm hopeful that maybe they have the means of assessing whether the electrical components of the boiler are still functioning, but perhaps that's wishful thinking! If that was the case I'm not sure whether my home emergency cover is valid because of the loss of heating, or whether it being an electrical issue means they wash their hands of it. I suppose I'll cross that bridge as and when.

But yes, the power cut's role in this does seem really odd. I've had no issues with the electrics before.

silvercar

In countries more prone to power cuts, it is standard practice to fit surge protectors to devices with electronics as turning the electrics back on can cause a surge.

FreeBear

battenburg88 said: I do have a sneaking suspicion that they boiler person is going to turn up and shrug their shoulders because the boiler can't turn on so they can't test anything. I'm hopeful that maybe they have the means of assessing whether the electrical components of the boiler are still functioning, but perhaps that's wishful thinking! If that was the case I'm not sure whether my home emergency cover is valid because of the loss of heating, or whether it being an electrical issue means they wash their hands of it. I suppose I'll cross that bridge as and when.

If the boiler engineer is competent with electrics, wiring the boiler up to a plug so that it can be used from an extension lead temporarily would show if it is the boiler at fault. But some boiler engineers won't touch anything electrical outside the boiler casing.

Just a thought - On my boiler, there is an on/off switch hidden under the bottom of the boiler where all the pipes emerge. If you have such a switch, turn it off, and then try resetting the RCD.

battenburg88

Quick update: a boiler engineer came out this morning. As suggested, they wired the boiler into a plug temporarily to test whether it was the boiler that had caused the fault - it wasn't. So I had to get an electrician out (not covered by the home emergency as suspected) who has managed to diagnose that it was a cable from a junction box up to a socket in the kitchen. Apparently it looked like it may have been chewed by a mouse at some point! 

That socket is now disconnected so that I can use everything else - boiler, fridge etc - and work out quite how I want it repaired.

Thanks for all the advice and suggestions on here. On the scale of things going wrong in my house lately, this has ended up at the slightly more manageable end of the scale but was stressful over the weekend nonetheless.