RCD tripping overnight with nothing connected

[leew85]

Good evening. Had a new consumer unit fitted a week ago, Paid over £500+vat for a proteus 5+5 board to replace an old non-rcd board. Ever since it was fitted the right hand RCD has tripped in the middle of the night, between around 11pm and 7am, every night. This powers a socket circuit, an oven, hob and an alarm. The oven and hob were isolated at the control switches and the ring had nothing plugged in. In order to attempt to figure out what was causing the tripping I switched off the oven, hob and ring MCBs, leaving just the alarm on, it still tripped. I then disconnected the 3 neutrals for those circuits from the neutral bar and taped them up, it still tripped. I then disconnected the alarm, leaving nothing connected to the load side of the RCD, it still tripped. So I called the guy to report my findings that I suspect the RCD is a dud, as cannot see why else it would trip with no load connected. He turned up, used an RCD tester to make sure that the RCD tripped within range, which it did, said the RCD was fine and left. Guy who fitted it claimed there was a borrowed neutral somewhere, but really struggling to understand how the hell that could cause an RCD with no connection to the load side to trip. Can anyone here explain to me how the hell an RCD with no load connection can trip overnight like this?
Thanks, Lee.

 

[brianmoooore]

I beat westward 10 to it, and got the company name from the video.
They have been around for over ten years, operate from a decent sized unit and get good reviews.

 

[leew85]

I beat westward 10 to it, and got the company name from the video.
They have been around for over ten years, operate from a decent sized unit and get good reviews.

Yep, which is why I choose them, so was not expecting to have this experience. To be fair, the average homeowner/landlord would not be aware of things like the excessive exposed copper, missing busbar cover etc and if the RCD had not been playing up I would have given them 5 stars as they were quick to respond to be initial enquiries etc, turned up when they said they would and got the job done on time which is more than can be said for some.

 

[stevethesparks]

Leew85, I am sorry for your current predicament but please stop poking your fingers around inside the unit, of which I assume is live!
Once you have got the contractor to return, demand the EIC (Electrical Installation Certificate) and also confirmation that they have registered this job to building control, then post up the pages with all the results.
Regardless of any payment plan/agreement, they should not have left you in this situation. Had it been me (and it would certainly have not) I'd be on my way to you now to get this sorted asap without any additional cost to you.
If they refuse your demands, as said get directly onto the NICEIC and I would also contact PayPal for reimbursement. You can always pay again once the situation is to your satisfaction.

 

[UNG]

Yes, only at night, no night storage heaters, no timed or light sensitive or PIR lights. Only things on overnight are the alarm, gas boiler and Google nest thermostat for said boiler.

Any fridge or freezer?

 

[leew85]

Any fridge or freezer?

nope

 

[brianmoooore]

Any fridge or freezer?

It's turning off with nothing connected to it. Neutrals and lives.

 

[littlespark]

Drop out the busbar to disconnect all the MCBs, and drop out the neutral link so the rcd is connected to nothing on the outgoing side. If it still trips out, then it must be a faulty unit, however this wouldn’t explain it only happens at night.

or

swap the left hand rcd with the right hand one and see if the problem moves with it.

These are only suggestions, and subject to competency level of the OP. But, ideally, the electrician that did the work should return and fix it. Preferably FOC.

 

[littlespark]

oooooh. Afterthought! (and I don’t know if anyone mentioned it earlier) but was there any mention by the electrician of having an SPD fitted to the board?

 

[leew85]

oooooh. Afterthought! (and I don’t know if anyone mentioned it earlier) but was there any mention by the electrician of having an SPD fitted to the board?

No SPD in this board, apparently not needed for domestic.

 

[leew85]

Drop out the busbar to disconnect all the MCBs, and drop out the neutral link so the rcd is connected to nothing on the outgoing side. If it still trips out, then it must be a faulty unit, however this wouldn’t explain it only happens at night.

or

swap the left hand rcd with the right hand one and see if the problem moves with it.

These are only suggestions, and subject to competency level of the OP. But, ideally, the electrician that did the work should return and fix it. Preferably FOC.

Don't feel confident dropping out the busbar myself, getting a couple of others to come and have a look at it next week to see if they can find any problems.
I did see a thread on another forum where someone was having problems with an RCD tripping when the streetlights come on here rcd tripping from streetlight switch on - https://www.diynot.com/diy/threads/rcd-tripping-from-streetlight-switch-on.146879/
Sadly the thread ends without a solution being found but would be interested to know how something external to an installation could cause an RCD to trip.
In my case it is long after the streetlights have come on but that does not rule out the possibility of something else in the street or even in a neighbours house affecting it?
Earthing is TN-S if that makes any difference.

 

[brianmoooore]

No SPD in this board, apparently not needed for domestic.

Not quite that simple. Depends on where you are in the country, the length and installation method of the local supply cables , and similar for the high voltage cables.

 

[Sadsyndrome]

Have you actually disconnected the loads from the Mcbs or just switched them off? Maybe you have a multiple issue e.g fault dodgy mcb letting current through to trip rcd with another fault like an earth fault or shared neutral which would explain why disconnecting neutrals hasn’t stopped issue. Very, very unlikely I know but there again so is an rcd tripping consistently at a certain time of day with zero current flow!