Likely causes for RCD trip.

[shedbang]

What testing did he do before he installed the new CU?

I don't know. I wasn't there (I have to work), but according to the wife they spent the best part of two days walking around the house with 'machines that beeped, fiddling with plug sockets'.

I can see you interpreting this as another attack on you, almost, but the problem is you genuinely don't seem to have any idea of what constitutes proper procedures.

Hey? Attack? No you're right - I don't know anything about 'proper testing procedures'. That's why I've hired an Electrician. You spend your life on this forum telling people to hire electricians. Make your mind up.

If he has "finished tidying" and was showing your wife how the CU works, then from his point of view it was finished.

Which means from his point of view he should have done all of the dead testing, all of the live testing, all of the tests should have been satisfactory, and all of the results and details of the work should have been recorded on an Electrical Installation Certificate.

So where is the certificate? He thought he was done, so why is there no EIC?

I don't know where he was in the testing process. Why are we trying to establish the competency of my electrician? All I know, is that as an ordinary punter, I intend to extract a certificate from him prior to paying him. I can hardly start an argument with him about the quality of his work when a) I was not there when he did it and b) I 'genuinely don't seem to have any idea of what constitutes proper procedures' based on the judgement of some random bloke on the internet whose qualifications I have no idea about and who has not seen the house, the installation or the situation!!

From my perspective he seems to be doing things right. Clearly some testing took place. Clearly the install has uncovered some other fault that went undetected. Does this ever not happen? Must it mean the testing was incompetent? He has vowed to come back and fix it and rescheduled his diary to do so. What more can I realistically ask for? Actually please don't answer that.

I don't understand the relationship between the FCU supplying the garage and the "fat 40A supply to the garage"...

The garage runs from a fused spur from the house into a small CU, with a max load of 13A, which is a touch inadequate for my needs. So he installed a new circuit for me which is at 40A at the CU. We haven't removed the old one.

 

[shedbang]

You can give the loft a clean, remove any junk, put down boards for moving about (if not already boarded) and put in some lights which are powered from a separate section of the CU.

I've done all of this, but at the last step I opened up the CU, got something wrong, really hurt myself and burned half the house down. Why did you tell me to do this? I don't think I'm competent...

 

[EFLImpudence]

I'd just like to say that everyone seems to be forgetting that it did work for three days.

Not ideal, I know, but something must have gone wrong since it appeared to be good.

 

[shedbang]

I'd just like to say that everyone seems to be forgetting that it did work for three days.

Not ideal, I know, but something must have gone wrong since it appeared to be good.

Thanks, yes, you're absolutely right. As nothing bar the boiler is attached to the circuit, my suspicions lie with the lighting that is on it. In particular today I found an aged security light which doesn't illuminate, but does appear to be on. We'll start with that. As the house is empty it's entirely possible it didn't trigger for 3 days.

 

[shedbang]

I think it's good practice to close down old threads, especially with a happy ending.

As suggested above, it did turn out to be the garage circuit (running off an FCU from the ring that was tripping the new RCD). We don't know what it is in the garage which is causing it, but as the building will be re-wired to the new CU in there in due course, there seems little point in finding out.

For the benefit of BAS, I do now have an EIC (that's a document that turned out to be a bit of a disappointment), I await something from Building Control (they're not speedy out our way). I paid my Sparky as a satisfied customer, and once the walls and floor are sorted in the garage it will be wired up and I shall be happy. For now.

And it wasn't the sockets I installed. For which I am pleased.

 

[SimonH2]

So where is the certificate? He thought he was done, so why is there no EIC?

Perhaps the guy is one who likes to produce professional paperwork - not something scribbled with a half-working pen (or several, in different colours) and covered in dirty marks from doing it with dirty hands while still on the job. And since the problem showed up, he's been late home so didn't do it that evening.

Just because there isn't a work of art printed certificate available as the guy is putting his tools away, doesn't mean that there won't be one by the time the guy wants paying.