New Consumer Unit Questions

[Ric]

Am finally getting round to replacing the old rewireable fuse box with a split load consumer unit. Wondered if anyone could clear up the following:

1) I am limited to how much space I have - the supply company changed the meter to a small digital one at some point before we bought the house and it was fitted centrally to the board with no concern for space conservation! The problem I have is that there is not enough room on the board with the meter/main fuse to fit a consumer unit of any reasonable size. There is also not enough room on the wall next to the board. My question is, is it permissible for me to put a board of my own (Plywood or MDF or some such) alongside and flush with the existing board, and then fix the new CU accross these two boards?

2) Going back to the size issue, it is severely limiting my choice of CUs- the only real split load candidate at the moment is a Wylex NHRS6304 but this seems more expensive than other (sometimes larger) CUs. Can anyone recommend any makes/models that are notably small in width? I am limited to a bout 340mm wide (Providing I can do what I outlined in 1!)

I don't really want to go down the non split load board with a mixture of MCBs/RCBOs unless I really have to.

Any help muchly appreciated, Ric.

[Andy Hall]

I don't believe that you are supposed to do that because the board with meter and fuses is the property of the supplier. Whether they would make you remove it is another matter.

You could perhaps use a stacking arrangement of two smaller CUs.

MK do this for their Sentry range - I have used it in my workshop.

The simple arrangement would then be to put the incomer plus non RCD circuits in one unit and the RCD plus its circuits in the other.

.andy

To email, substitute .nospam with .gl

[Andrew Barnes]

Why don't you get the electricity company to come and move the meter? They did this for me no problem.

[Christian McArdle]

it > was fitted centrally to the board with no concern for space conservation!

Technically, you're not allowed to use their board anyway.

to > a bout 340mm wide (Providing I can do what I outlined in 1!)

Would a long board fit next to it rotated 90 degrees? Alternatively, can you fit two small boards, one with an RCD incomer and one with an isolator?

Christian.

[Ric]

Suspected this was the case and yourself and Andy have confirmed it - I just assumed that people did anyway- is it definately a no no?

Unfortunately not, to the left of the board there is about 200mm which is less than most CUs appear to be high. I think I would also be pushing it trying to get two smaller boards in the height available. It is looking more and more likely that I am going to end up with a smaller board than I would have liked (say a 5 way Wylex board or the likes) and use a combination of MCBs and RCBOs.

[Andy Hall]

It will be if the supplier takes exception to it.

It would be a bit tearful if you had to take the CU off and rewire it.

So personally I'd play by the rules.

.andy

To email, substitute .nospam with .gl

[a]

how about ringing them up to ask? Seems they dont care about fuse seals these days so why should they bother about you using a bit of their mounting board?

[Andrew Gabriel]

You'll find that if it develops a fungal infection which starts spreading towards your wood, that board magically becomes 'your' board, even when it has a metal plate stapled to it saying it is the property of London Electricity Board.

[Christian McArdle]

I suppose technically, I should remove the various components that accidentally got mounted on it, too, even if it did end up with fewer components than before (it was a small board and I couldn't fit the new CU on it, like the old fuse board had been).

Christian.

[Dave Plowman (News)]

I removed mine which was mounted on a brick wall at the top of the cellar stairs, and dry lined the wall. So everything is now neat - all the cables go behind the dry lining.

Should I hang on to the old board in case they want it back? ;-)

[Steve Walker]

They certainly don't care in my house - their board fills the cupboard (about 2' wide x 2'6" high, so there isn't anywhere *except* on their board to put anything! There's now a modern CU, a bell transformer and a socket for the answerphone power supply in there, but even the old fuse unit was mounted on their board.

[Ric]

Fair point - I have decided then that the best route may be to go down the RCBO route - I should be able to get a five way CU which should be enough. I would have ideally liked to leave some more spare ways for expansion but I'll just have to live with it. As the individual circuits will be independantly RCD protected I would like to put the lighting curcuit on an RCBO (Is there any reason why I shouldn't do this?) rather than just an MCB but can't seem to see any 6A RCBO's anywhere - does anyone do them?

[Christian McArdle]

I don't know. Most lighting circuits could be 10A. Can you find one of these?

In any case, there's no reason to put a lighting circuit on an RCBO, although it is much safer than putting one on a shared RCD. If there's an electrical fire, it is probably better than the lights stay on even as the cable burns away. The fire is unlikely to have actually started in the light circuit anyway.

Most failure modes in a lighting circuit would either be benign, or would blow the 6A MCB pretty sharp anyway.

Christian.

[Andy Wade]

MK Sentry range, list no. 6932s = 6 A RCBO (Type B / 30 mA )

For full range see

[Ric]

It just occured as a posibility. We've just moved into the house and last week I decided to replace the architrave around the bedroom door - I pulled the old stuff off and found that some smart arse had routed the cable for the landing light switch behind it. On closer inspection I saw that one of the screws in the bottom hinge of the door was skewering the cable. Grabbed my meter and sure enough the hinge was live! Anyway, I thought that in a house where there could be more suprises to come it could be worth putting the lighting curcuit on an RCBO - at least until I have investigated enough to ensure there are no other problems

[Christian McArdle]

Ouch! I'd beg or borrow some proper test gear and do a full electrical inspection, if I were you! (It might not find all the baddies like this, but it's a start!)

Christian.