DIY Doctor

Move a consumer unit

Postby kipwad » Sun Oct 26, 2008 9:37 am

Hi to you all
I should say at the outset I am a retired electrician, which sort of proves
you're never to old to learn.
I'm changing the garage into a bedroom and need to re-site the consumer unit. The meter box is on the outside wall and feeds the consumer unit via 2x25 mm double sheathed tails through the wall cavity, standard stuff. The new site for the consumer unit will be some 10m away, and as I need to get this right the first time, I could use some good advice as to what cable and protection I need to install so as to comply with all the relevant regulations etc

Thanks in advance
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Simply Build It

Postby ericmark » Sun Oct 26, 2008 6:40 pm

In order to mount the consumer unit remote from the incoming supply you need an isolator at the incoming supply. I think this is fire regulations rather than electrical regulations at least I have never found it in BS7671.
Second problem is protection of cables with the new regulations see 522.6.6 I think that's the regulation. You can't protect with RCD so either SWA or trunking etc.
I am sure you are aware of Part P there is a link on projects.
The new 17th Edition BS7671:2008 is a pain with all the RCD rules and buried in wall rules. It's not cut and dried and there are many options and for you there is an ace you can play in that it is under supervision of a responsible person. I would not want to play the Ace as it would not help with house sales.
But there seems to be some disagreement in translating the BS7671 and as a result you will find conflicting advice only way is the read it yourself if your signing the completion cert. Or if someone doing it for you then get their advice first.

Postby kipwad » Tue Oct 28, 2008 10:01 am

Hi Eric
Makes you long for the good old 13th edition! Having been retired for several years I'm definitely out of touch with all the latest regs etc. Thanks for the advice, much food for thought
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Postby ericmark » Tue Oct 28, 2008 10:29 pm

I well remember in 1989 returning to the UK and having a young electrician with me it seemed with every other sentence saying the 16th Edition says. Although he had a big mouth not quite big enough to shove the 16th Edition down. But as time went on I found I was getting into trouble on a regular basis for not following the regulations which had now become a British standard. So I finally went back to school and took course and exam.
The main thing I realised was people seemed to use Chinese whispers as to it’s content and often it did not say what people said it did.
Some of this was due to it being in some old regulation book an example was cooker isolators. And also some of the regulations had been moved from the main book to the guides. Number of cables in a conduit etc.
Now we have even more books from Part M (Height of sockets etc.) and Part L (Energy saving) and Part P (Registering work with council) plus ESQCR supply regulations and it has reached the stage where one feels one needs a degree in law.
I is easy to find a regulation to say you can’t do something it’s finding what you can do which is the problem.
The 522.6.6 A cable concealed in a wall or partition at a depth of less than 50 mm from a surface of the wall or partition shall: is becoming a real problem as it says nothing about what type of supply or voltage it refers to and protecting a cable with earthed metallic covering or 522.6.7 Where Regulation 522.6.6 applies and the installation is not intended to be under the supervision of a skilled or instructed person, a cable installed in accordance with Regulation 522.6.6 (v). and not complying with Regulation 522.6.6 (i), (ii), (iii) or (iv), shall be provided with additional protection by means of an RCD having the characteristics specified in Regulation 415.1.1. This is not possible where SELV supplies are involved yet there is nothing to exempt SELV circuits from the regulation.
It is plain therefore there are errors in the regulations and some common sense is required.
There are also other blatant errors else where in that Part P refers to BS7671:2001 which has been withdrawn and is not available in Welsh which means the issuing authority has broken the law which brings the whole set of regulations into question.
The fact that my local authority Flintshire do not issue completion certificates when they fit a consumer unit makes one realise the local authorities are not really interested.
There have been court cases and people have been found guilty of not complying with Part P but every one also has substandard work as well I have not seen any for purely breaking the Part P laws without also being substandard work involved as well.
The fact that very few councils know what they are doing and the building inspectors in the main do not have a clue as to electrical work yet are responsible for site safety.
I have seen so many badly filled in installation reports. My son was telling me the other day how they had changed to format and he had not noticed and had put readings in wrong boxes. This should have been picked up by his boss, and the overseeing group plus the LABC but was completely missed.
I have seen TT supplies with earth rod measurement of less than 1 ohm who are they kidding it is quite plain they have not measured just the rod but have left all bonding connected. Done it myself but with a note to the effect unable to turn off supply etc. but seen these readings entered as Ze.
House bashing was always a young mans job where speed was main requirement but now it’s more skilled than some of the maintenance work with more test equipment than we could have ever aspired to when I was a young lad. Palm tops seem the norm.
Time I retired too Eric

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