Consumer Unit Rating

7 Jul 2004
Reaction score
United Kingdom
I presently have a gas cooker. I want to change to an electric hob and oven. The consumer is rated for 80Amp. There is no spare slot for a 32Amp MCB. However, when I add up the ratings of all the fuses installed in the consumer unit it comes to 70Amp, leaving only 10Amp before the rating of the box is exceeded. As all these circuits will not be loaded at anyone time can the total rating of the all the fuses exceed the rating of the consumer unit?
Sponsored Links
yeah that shouoldn't be a problem we don't expect everything to be on at once

as to the problem of physical space in the CU i see a couple of soloutions

one is to henly in a seperate small CU but this is not a job for begginers and is something i would aviod where possible

another option (assuming you have 2 lighting cuircuits) is the following

remove lighting cuircuits from CU (thus freeing 2 slots)
fit a 16A mcb to CU (this still leaves one slot free for your cooker)
from the 16A mcb run 2.5mm cable to a grid plus box
in the grid plus box fit two 5A fuses one for each lighting cuircuit

to build up the grid plus box you will need

2 of theese

1 of theese

1 of theese

a normal plastic surface box
and a single segment of chock block to join up the neutrals
In theory, couldn't you just uprate the lighting circuit to 10 amps, and use a junction box to connect the two to the same MCB?
Sponsored Links
then we get into the old argument of

should 10A switches be used on a 10A lighting curcuit
plus it would be an issue if in future anyone wanted to use 5A sockets (for lamps controlled by lightswitches) or plug in pendants or SES lampholders or SBC lampholders on that lighting cuircuit
Actually, wouldn't the issue arise with use of 2a sockets, rather than 5a sockets? It is fairly standard to have 2a sockets on 5 amp lighting circuits, so surely the limit for 5 amp sockets would be on a 10 amp circuit or something?

Just assuming, I know it's a bad practice, I don't know too much about BS546 sockets, except that a 15 amp socket goes on a 16 amp radial.

I suppose though your answer is more versatile, and given that no further questions need be asked, yes, I suppose you have a better solution.
a lot of people use 5A sockets rather than 2A ones because the 2A variety are not shuttered (at least in mk)

and there is still the issue of someone wanting to fit fittings that take ses or sbc lamps

overall i still prefer the idea of fusing the cuircuits at 5A each in a grid box
True, I think you have a good solution, taking more into account.

A problem with putting 5 amp sockets on a 6a lighting circuit is accounting for load. 2 amp sockets need to be accounted for as a minimum of 0.5 amps, whereas 5 amps are generally counted at half their load (2.5 amps), so you can fit more 2 amps on a circuit where safe.

I think the 2 amps aren't shuttered because the requirement for it is negligable due to the small size of the pins.

As for the 5 amps, I would like to see us using an equal pressure shutter like they have in German sockets, and plugging europlugs in them, as I read they fit quite well, and it would have enough protection at the CU.
im sure its come up and turned into a long argument several times before

cazn't rememebr for sure whether it was here or on screwfix directs forums though

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

Sponsored Links