Replacing a Consumer Unit

[BraileTrail]

Hi,

I am going to replace our old cartridge fuse consumer unit with a new split-load one. While I am at it, I am going to move it from its current inconvenient position (currently you need a step ladder to reach it) to some where more accessible in the dark. So I need to extend the meter tails by about 1m. Having read the archives, I am going to contact my supplier and tell them the fuse seal will be broken to install a new CU, then after removing the old CU I will put in a Henley block to extend the tails down to the new CU.

My question is this, what is the best way to extend the various circuits down to the CU, there is a little slack in the current wiring but certainly not 1m. Would joining them with chocolate block of the appropriate rating be OK? I would put it in some sort of secure plastic box rather like a central heating wiring centre box.

Thanks, BraileTrail

[BigWallop]

Crimp connectors for all the PVC circuits is the best way to extend them. As for the meter tails, you're better to remove the main fuse at the head end and replace with tails directly from the meter to the new CU. Using Henley blocks is OK if you wish to tail off to another CU for an outhouse or garage, but if you're only intention is to supply a new CU from the meter, then new one piece tails direct from the meter is better than joints.

[BraileTrail]

Thanks for the advice re the meter tails.

In message , BigWallop writes

Do crimp connectors meet the current wiring regs? I am thinking we may have to have an inspection when we sell the house.

Thanks, BraileTrail

[Owain]

If you put a battery-backed-up emergency lighting unit next to the CU, it won't be in the dark when the power goes off. You could put another one near where you keep the stepladder, although MCBs can usually be poked on/off with a window-pole or similar.

Would that be a sufficient solution to the accessible-in-the-dark problem and save you a lot of work: ;-)

Don't. They will probably witter on at you about Part P. Just pull the fuse, *ensuring there is no load on the circuit*.

You would probably be better putting in a 100A switch-fuse at the current CU location. This may be required for meter tails >1m. This will also isolate the supply to the new CU when you're poking about inside it.

Crimps, or DIN rail mounted terminals in a DIN rail box.

When you are running the cables to the new CU you may have to take cable grouping factors into account.

Owain

[Bob Eager]

Having a joint in the tails is not a particularly good idea, IMHO. But OTOH you shouldn't be breaking the meter seals to put in new tails.

I'd 'join' the tails by putting in a 100A isolator. Useful in the future...!

[Andy Hall]

Yes they do for this purpose. You do need to house the single wires in some auitable way. You also need to use good quality crimps with the correct crimping tool - available from an electrical wholesaler such as Newey & Eyre, TLC, WF, etc.

There is new legislation as of April this year, Part P of the Building Regulations. Many discussions on this have taken place on this newsgroup. The type of work that you describe, certainly falls within its scope.

Your options if you wish to comply with the legislation are:

- Employ an electrician who is a member of one of the approved organisations such as NICEIC. He can do the work, inspect, self certify and give you a certificate.

- If you want to DIY, use the Building Notice procedure c/o building control at your local authority. There will be a fee for this and the work should be inspected and certificate issued.

If you don't care about the legislation you can opt to do nothing. At the time that you sell, an inspection may be initiated by the purchaser. You may also be asked about works that you have carried out by the purchaser's solicitor. A diligent one may pick up on the lack of certificate and post April 2005 work (though it is unlikely I think and hard to prove) and if you answer truthfully, there would need to be a regularisation done with the local authority. The cost for this is not a lot different to the building notice procedure.

[Andrew Gabriel]

Some meters have a separate cover over the consumer's meter tails, although most don't. You should not break any seal on the meter, which may mean you can't connect new tails to it.

[Dave Plowman (News)]

I'd say absolutely not - unless they are in a position where they are mandatory.

[BigWallop]

Why would you say that? What alternative would you recommend, and why?

[John Rumm]

They do. You will also want sleaving over the overall cable once the individual wires are joined. Heatshrink sleaving (CPC do wide sizes on reels in white and grey - which works well on T&E cables).

To get the neatest join, strip three inches or so of the overall sheath off the wire and then leave one conductor full length, then cut each of the others about one inch shorter that the previous one. Cut the conductors of the mating bit the other way round so the wire ends will all meet up. That way you don't end up with a bunch of crimps all side by side which creates a big bulge in the wire which makes it take more space and makes it harder to slide the overall sheath over the join.

[Dave Plowman (News)]

I'd not joint cable anywhere where crimps were the only 'legal' way - I'd replace it. I've seen too many badly made. So I'd not recommend them for amateur use.

[John]

Have a look at the meter, some recently installed have a isolation switch which will allow you work on the CU and Tails, while others you will need to remove the fuse. I would look at installing a Henley Block (Sometimes called LN block), and a earth bar. All of these can be bought from ScrewFix.

If the CU is near a ceiling, can you not put proper joint boxes above the ceiling, if you use crimps you will need to provide a box to protect the joints, while with proper joint boxes protection will not be required.

J

[John]

Only if you provide additional mechanical protection, this means you put everything in a plastic or metal box (Which will require earthing). These can be bought from City Electrical or any similar outfit.

By the time you have messed around with extra box(es), with all the glands, and finding a place for it, you could have bought a set a of 6 amp, 20 amp and 32 amp joint boxes and fitted them.

If you do everything by the Wiring Regulations or On Site Guide, you will not have anything to worry about.

J

[BraileTrail]

Thanks to everyone for the informative replies.

BraileTrail