Electrics fault with rcd protected circuit

I've just had the electrical second fix completed by my electrician for our loft conversion. Before leaving he did a number of tests on the new upstairs circuit. The circuit is a radial with 5 double sockets, the floor area is approximately 35m2. The electrician left and I assumed all was okay and that I would get an electrical certifiacte for submission to building control ahead of getting a completion certificate. I phoned the electrician to discuss payment and he (the boss of the younger guy who did the work) told me that the guy who did the tests said that he in not comfortable signing an electrical certificate because some of the test readings cause him concern. He said that when testing the rcd protected circuit his meter would sometimes read very few ohms and then when he would re-test it would read high numbers of ohms. I not quite sure what this means, he later checked his equipment and says that it is functioning normally. Can anyone tell me what the possible/ probable causes may be for fluctuating readings when testing the circuit?

Many thanks.

Your electrician should answer this question, thats why you paid him.

He should give you another price to fault find problems with the existing circuit.

I would like to have an idea of what the fault might be because
a.) I don't want to be ripped off and lied to by the electrician
and
b.) I'm worried this might be a spanner in the works of what was a reasonably smooth loft conversion which took me over a year to do almost entirely single handedly, no other laubor except this electrician!

londonboy said:

He should give you another price to fault find problems with the existing circuit.

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What ??

Why pay more for a problem to be solved, the problem was part of the OP's spec'd work and as such the guy should return and resolve the matter as part of the job. Not at extra cost !


OP

So run us through the work he did. New radial 5 sockets, where did the lights come from ? Added on to the floor below or a 2nd new circuit (with the 1st being the radial loft sockets).

Did they add to a board with spares or provide a separate board, or a new board for the whole house ?

What is on the trouble board as far as other circuits, mcb's, rcbo's and rcd ?

The way I read it the fault is with an EXISTING circuit not the newly installed one.

The lights are a seperate circuit on its own fuse. I didn't replace the fuse box, there is a seperate rcd connected to the new upstairs radial circuit.

The loft was previously converted in the 80's, I stripped everything back and started again. thus there was power in the loft (2x doubles Radial) before I started. The electrician formed the new radial circuit from the 80's cable which ran from the fuse box to the loft. I didn't want the plasterwork ruined in the room below as would be nessesary to find a new cable route for a ring circuit so the electrician removed most of the old radial circuit (sockets and cables) and joined the new radial circuit to what remained of the older cable which dated from 83. Length of cable re used a few metres, 4 or 5.

ollieman said:

The lights are a seperate circuit on its own fuse. I didn't replace the fuse box, there is a seperate rcd connected to the new upstairs radial circuit.

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Where is the rcd, on the main board, on it's own board with onlt the loft radial, or what ??

Your reply does not state if the rcd is new or was it existing. An rcd on a board normally controls a bunch of different circuits.

How did the guy join the old wiring for the radial to the new, at the 1st socket or in a junc box ?

You really need to be clearer as to what you have, at the fuse board.

RCD faults can be anywhere, so if the rcd controls 4 or 5 circuits the fault could be steming from a single circuit or even a combined leakage over all the circuits.

Please detail the rcd and what it controls (circuit wise), also confirm if rcd is new or existing in situ.

The RCD is brand new and fixed onto the same ply backing as the main fuse board which itself is from around 1990. Th RCD is linked only to the new upstairs radial circuit. The cables were joined by junction box. I hope this makes things clearer.

Could well have been a large variation in the readings (presumably earth loop impedance?) due to use of the low-current ELI test mode to prevent the RCD tripping during the test. Apparently this can be quite susceptible to electrical noise and the like.

Presumably the electrician performed at least continuity and insulation resistance tests on the short existing section of wire before deciding it would be appropriate to re-use it?

In all honesty, I'm not sure there's a lot more you can do other than have the electrician and his boss return and perform the tests again. Without knowing more about the testing performed, it's difficult to advise further. For example, what were the R1+R2 readings?