GROUPING

[DAJ]

1) I have split my lounge light circuits in two - thus 2 x 6a RCBO's feed one room. I done this because one of the RCBO's feed a total of 12 x 50w dimmerble halagen spots and the other RCBO 8 x spots (same). I've now been told by an electrician, I should have used 2.5mm and not 1.5mm - is that correct?

2.5mm on a 6A RCBO? No, 1.5mm is more than adequate unless (off the top of my head) completely surrounded by insulation, even then it might be ok.

2) At the rear of the consumer unit, I have colour coded each cable, or pairs of cables, by taping them together using various coloured insulating tape. For example, I have "grouped", using tape, about 18" of the tails entering the CU. I done this to easily identify each group when connecting them up to the RCBO's and to help those that work on the CU in the future. Again, the electrician has told me that this can cause a fire. true?

Can you post a picture?

3) I have used 10mm cable from the 40a RCBO in the CU to the cooker outlet (about 9m). This will feed a 5.7kw oven and from that, 6mm cable feeding hobs totaling 5kw (dominos). I done this because I thought a 40a RCBO could feed around 13000w. Once agian, the electrician has told be that I've messed up! I should have used 10mm on everything including the feed to the hobs. he also said that a 40a was not enough! True or false?

How big is your house? (it is a relevant question) What do the MI's say about electrical connection of the appliances? What kind of hobs are they (ceramic, induction etc) and how many rings? How did you calculate 13kw? 40A may not be adequate for this load. WRT cable size, there is some debate about the sizing of the final connection to cooking appliances but it seems to be generally accepted that if there is no guidance in the MI's then the appliance can be connected with a cable which exceeds the max draw of the appliance but not necessarily as large as the circuit cable. In any case 6mm t&e at 9m length can safely carry 40A, although there may be ambient temperature factor to consider.

4) One of the 32a RCBO's at the CU, feeds outside 2 x 2 gang sockets which are RCD protected. He (the electrician) has told me that you should "NEVER" put an RCD on a circuit protected by RCBO's.

If anything it makes the installation a tiny bit safer because if one RCD was faulty there would be a back-up but it is generally seen at the least as unnecessary and pointless, there are discrimination problems and it can increases the inconvenience in the event of a fault/faulty RCD. Ideal solution would be having a protected/surface run/deeply buried cable on the non-rcd side and have the RCD at the outdoor socket and but simply changing the outdoor sockets for normal weatherproof ones would regularise the setup and satisfy any departures for the regs relating to discrimination and inconvenience. I'm sure there a few threads on here where it has been discussed.

5) I installed, from scratch, 3 light circuits and 4 x socket rings (extension, loft conversion and terrace). In doing so, I had to provide a neutral feed to all light switches because I installed X10 light switches. I installed all the switches (20 of them!!!) and they all operated perfectly when commanded to either by switching them on manually or via the computer/mobile phone. the electrician has told me that i could face prosecution for installing neutral feeds to switches!!!!

There are problems if you have data cables alongside mains or sharing the same enclosures. There is absolutely nothing wrong with having neutrals at switch location and for an electrician to tell you otherwise suggests he must be a con merchant or dangerously incompetent.

There are other things he said, but they'll keep for another post. he has told me that the whole lot needs "ripping" out" and doing by a "qualified sparks who knows what hes doing mate". I am so down now. I've spent months and months of research and man hours, not to mention money! I was, and still am, proud of the level of workmanship I have achieved, but now worried that it all may have to be done again. HELP!!

If you had done much research on here you would have found many people who are told to involve an electrician from the start, or notify building control and find out their procedure for DIY rewire attempts. You have not done this . . . WHY!?

What were the other things he said?

Lets have some pictures of your work so we can assess your workmanship.

Thanks for your help mate.

 

[DAJ]

What was the actual reason for this electrician to appear on the scene? The answer to this may well affect any answers given.

I asked a local builder to give me a quote for repair work to a chimney. he turned up with another guy "electrician". I took my family out for lunch today and found out he is, in fact, a roofer who works part-time as an electrician for the builder!!!!

 

[DAJ]

I've tested all the circuits, one by one and all on together with no problems

Could you scan or photograph your schedule of test results and post it?

I've now been told by an electrician, I should have used 2.5mm and not 1.5mm - is that correct?

I feel competent

- that means you know how to design circuits, know what the current carrying capacity of your cables are given their installation method, grouping and other de-rating factors, what the voltage drop will be and therefore you know whether you should have used 1.5mm² or 2.5mm².

GUESS YOU BUILT THE ARK THEN!

2) At the rear of the consumer unit, I have colour coded each cable, or pairs of cables, by taping them together using various coloured insulating tape. For example, I have "grouped", using tape, about 18" of the tails entering the CU. I done this to easily identify each group when connecting them up to the RCBO's and to help those that work on the CU in the future. Again, the electricain has told me that this can cause a fire. true?

I feel competent

- that means you would have applied the necessary grouping factors when working out the cable sizes.

Once agian, the electrician has told be that I've messed up! I should have used 10mm on everything including the feed to the hobs. he also said that a 40a was not enough! True or false?

I feel competent

- what was your design load allowing for diversity?

the electrician has told me that i could face prosecution for installing neutral feeds to switches!!!!

I was, and still am, proud of the level of workmanship I have achieved, but now worried that it all may have to be done again. HELP!!

I feel competent

- that means you must know if it's any good.

 

[1john]

Basically you think you have done an excellent job and someone has disagreed so you have got upset. Post pics of your work and we may see your side of things. Some of what the roofer/spark has said is nonsense but without pics we cant confirm or really advise mate. Get some other local guys in to have a look too, go direct to the sparks though, not via builders.

 

[DetlefSchmitz]

What was the actual reason for this electrician to appear on the scene? The answer to this may well affect any answers given.

I asked a local builder to give me a quote for repair work to a chimney. he turned up with another guy "electrician". I took my family out for lunch today and found out he is, in fact, a roofer who works part-time as an electrician for the builder!!!!

I still don't quite get it. You asked a builder to quote for repair work to a chimney. He brings along a roofer who pretends to be an electrician who then, out of the blue, examines all your wiring. Why?

 

[DAJ]

Basically you think you have done an excellent job and someone has disagreed so you have got upset. Post pics of your work and we may see your side of things. Some of what the roofer/spark has said is nonsense but without pics we cant confirm or really advise mate. Get some other local guys in to have a look too, go direct to the sparks though, not via builders.

AT LAST - Thanks, I consider that sound advice and EXACTLY what I intend to do. I am positive the work I've done is fine, the first fix was checked and OK'd by a QE but I reckon it's time to put my mind at rest and get him back. You're absolutely correct in what you say about me thinking I've done a excellent job (and also that I'm a little upset at the reaction on here) and what you say about pictures is correct too.

It's my intention to post some pictures, as soon as I have uploaded them.

Thanks again for your advice.

 

[DAJ]

What was the actual reason for this electrician to appear on the scene? The answer to this may well affect any answers given.

I asked a local builder to give me a quote for repair work to a chimney. he turned up with another guy "electrician". I took my family out for lunch today and found out he is, in fact, a roofer who works part-time as an electrician for the builder!!!!

I still don't quite get it. You asked a builder to quote for repair work to a chimney. He brings along a roofer who pretends to be an electrician who then, out of the blue, examines all your wiring. Why?

Oh dear, Ill try and explain - There is some lead flashing that needs to be replaced around the chimney and the pot needs replacing. The builder came with this other guy, I assumed simply a mate. He didn't "examine" my wiring, he asked me how I'd done it (sockets, CU etc. all in situ finished). he then began to take sharp intakes of breathe and shook his head. he seemed to know what he was talking about up to the point when he refered to things I have mentioned here. later, i found out he was a roofer who was going to do some of the work on or around the chimney!