Consumer unit replacement


Postby Beaufighter » Sun Mar 15, 2009 5:39 pm

Hi, I need to replace the existing consumer unit for one that has a bigger capacity. At present there are only six circuits but due to an extension, loft conversion and conservatory I need to more capacity so that individual circuits may be run. My question is basically, how do I replace the existing unit as far as the feed from the supply meter is concerned? I am conscious, of course, that this is live so how do I isolate this and make it safe before I commence work and then return the connection so all is back to normal.

Any help and advice appreciated.
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Postby kbrownie » Sun Mar 15, 2009 9:14 pm

Hi Beaufighter,
This is not a DIY job and needs to be done by a person that has the skill and knowledge and is compentant to do so. It must comply to both part p and BS7671:2008
The best advise I can offer is get an electrician in that is qualified to the scope of part p or registered with a domestic electrical installer scheme.
KB
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Postby sparx » Sun Mar 15, 2009 9:25 pm

Hi, your local electricity supply company will usually fit a local isolator switch if requested by a 'part-p' registered electrician who should do this very non-DIY job anyway.
A change of consumer unit is reportable to Local Building control and must have test certs. issued afterwards by qualified electrician using calibrated instruments.
regards SPARX
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Postby Beaufighter » Mon Mar 16, 2009 10:01 am

Thanks for the replies. I thought that it may not be so straightforward as I had hoped. Am I right in thinking that once a qualified electrician has installed a new consumer unit it is ok for a competent DIY'er to wire any additional circuits into this as the need arises?

Failing this, as I am just completing the build of conservatory, would there be any problems in extending the existing ring main into this. By this I mean not just to take a spur but to extend the ring into the conservatory from a suitable point, continue the ring and return to where it was taken from. Hope this makes sense and any help and advice appreciated.
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Postby kbrownie » Mon Mar 16, 2009 7:11 pm

Hi Beufighter,
I'll cover a few important relevant points,
You can as a DIYer do any electrical installations in your house providing you apply to your local building controls outlining the work you intend to do. They charge a fee for this!
If it's a new CU you are installing an electrical installation certificate, schedule of test and schedule of inspection will be need to be completed.
Any new circuit from the cu will need a electrical installation cert
Any additions or extension to existing circuits will need a minor works certificate, all these test will need to be made using the relevant test instruments and have a current calibration certficate.
It's a compliated process if you don't know what you are doing you will need to be aware of what the right setting of the meters should be on, what a good reading is and what a bad reading is. Some of these test do put a voltage through the systems and some are live test.
The meters are very expensive if you decided to take this route, my experiences are that it is easier and cheaper to employee a suitable qualified electrician to perform these tasks.
KB
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Postby Dadwood » Mon Mar 16, 2009 7:52 pm

I am ignorant when it comes to things electrical (indeed both kbrownie and sparx have given me valuable advice on a couple of matters in the past) but this question about replacing a consumer unit has got me wondering. So, purely for my information can you tell me: 1. In order to work safely, one must presumably remove the large live side fuse positioned upstream of the meter. If so, this fuse is normally fitted with a tamper proof seal to prevent unauthorised removal. But can that fuse be legally removed by any suitably qualified electrical engineer? or must it be done only by the electricity supplier's staff?
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Postby sparx » Mon Mar 16, 2009 9:30 pm

Hi agn. any new or rewired circuit is also reportable.
Any new work must comply with 17th edition which means even just extending an existing ring the new part must be RCD protected. Since this is not possible to do, there are 2 possibilities, either fit an RCD fused spur from ring and run conservatory radial from it or the whole ring must somehow get RCD at source, back to square one!
Sorry but I really don't understand why so many people think it's ok to DIY potentially lethel electrical work but wouldn't touch gas piping which kills 1/50th of the number of people!

please get a registered electrician in who can certify his work and register it with local authority.
'Competetent DIY'er' is an oximoron, "Competent"- Having sufficient knowledge, training & experience so as to avoid danger.
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Postby Beaufighter » Mon Mar 16, 2009 9:43 pm

Thanks for reply Sparx. I take your point about the safety issue and accept that it will be wise to have this work professionally completed. I shall wire in extension leaving the tails of wires to be connected to where he sees fit and get him to test my work. Hopefully this is a compromise on cost without compromising safety. Take your point about the oxymoron though, as a carpenter I regualy go to people who have had a go but end up with something that is not up to scratch.

Thanks again for help.
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Postby kbrownie » Tue Mar 17, 2009 12:40 pm

Dadwood,
in reply to your question, this equipment belongs to the supply company and it should not be removed or tampered with unless they do it.
KB
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Postby ban_all_sheds » Tue Mar 17, 2009 2:41 pm

[quote="Beaufighter"] By this I mean not just to take a spur but to extend the ring into the conservatory from a suitable point, continue the ring and return to where it was taken from.[/quote]

Be careful how you do this as you may end up with a figure of eight and not a ring. taking a feed from the socket, into the conservatory to the first socket then from the last socket in the conservatory back to the old socket you came from, yes, but that cable needs to be terminated to cable that was going off to the original next socket and not screwed into the socket terminals and the joint available for inspection and testing.

You should also note that by trying to do the half the sparks electrical work for him like al the cable routes and then say covering them up with plaster, boarding and the like he will be unable to confirm corrrect cable routes and inspection is just as important as testing.
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Postby Beaufighter » Tue Mar 17, 2009 2:45 pm

Sorry kbrownie I just need clarification please. Are you saying that once I have had a new consumer unit fitted, which I have bought and paid an electrician for installation, it is then the property of the supply company? I am given to understand that the supply company only have ownership up to the input side of the consumer unit.
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Postby sparx » Tue Mar 17, 2009 8:12 pm

Beaufighter, I believe KB's reply was to the question about the 'cut out' fuse which does belong to the REC (regional electricity company) & legally only they can break the seal, except for some REC's who will allow members of certain organisations to do so and tell them so they can reseal,
regards Sparx
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Postby kbrownie » Tue Mar 17, 2009 9:28 pm

Sorry Beaufighter, Your post had been hijacked and I was answering a question from Dadwood. As Sparx has pointed out.
The consumer unit belongs to you.
KB
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Postby Dadwood » Wed Mar 18, 2009 9:44 am

Hi kbrownie,
Thank you for explaining that the large sealed fuse on the incoming live belongs to the electricity company and can only be removed by their engineers. Now, is it correct to say that a consumer unit cannot be replaced safely unless that fuse is removed? And if so, does that mean that only the local electricity company can replace the consumer unit?
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Postby kbrownie » Wed Mar 18, 2009 12:04 pm

Hi Dadwood,
The Electricty at work regulations, which is a legal document, does state that electricity should not be worked on live.
So this being true the fuse needs to be moved, if there is no other safe means of isolation. It is ilegal to remove this fuse unless as sparxs has mentioned an assosiated party of the supply company who has been authorized to do so.
This can be pre-arranged so the CU can be replaced by your electrician, Your Local supply company won't replace the consumer unit.
KB
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