additional consumer unit

[kinhell]

I'm having a new kitchen built in the summer. Its on the opposite side of the house to the external fuse box. I'm thinking that it might be a good idea to have an additional consumer unit in the new utility room. This will mean just running 1 cable from the fuse box to the new consumer unit. I was thinking of running the cable myself and get the electrician to connect it when they build the extension.
I will need
1 ring curcuit for the appliances in the kitchen,
1 ring curcuit for the appliances in the utility,
1 lighting ring for the kitchen,
1 lighting ring for the utility,
Separate connection for the cooker and hob.

Can someone tell me what size cable I need so I can get the boards up and get the cable through?

The new consumer unit will be a couple of metres from the gas meter( but I want to get the gas meter moved)
Is it best to leave the gas meter there for earth bonding or will the sparky just connect up the earth cable at the other end in the original fuse box?

I need to find out so that I can plan having the gas meter moved .

 

[davy_owen_88]

Do you know the power rating for the cooker/oven/hob? Without those there is little advice we can give that would be of much use besides install the biggest just in case.

Oh, don't bother fitting 2 lighting circuits, 1 will be more than sufficient and instead of 1 ring per room just install a single RCD protected ring circuit feeding both rooms and install a 20A radial for the fridge/freezer from the non-RCD protected side.

The gas should be bonded to the main earth terminal, which will be at the original CU.

 

[kinhell]

Not decided on the cooker or hob so what would the maximum sized cable you would reccomend?

Thanks for the advice about the ring circuit. Much appreciated.

 

[davy_owen_88]

Not decided on the cooker or hob so what would the maximum sized cable you would reccomend?

Thanks for the advice about the ring circuit. Much appreciated.

I would advise you get a gas hob and an electric oven (hobs use loads of 'leccy) and that would help keep the cable size down.

32A ring
32A radial for double oven (although with diversity you could probably get a hob onto this too..)
20A radial for fridge/freezer
6A lighting

50A MCB and 10mm² cable should be ok assuming no de-rating factors are applied to the cable. These derating factors include running in conduit/trunking, running in insulated loft/walls, areas of high ambient temperatures and being bunched together with lots of other cables. Will any of these apply to the cable run from current CU to the new CU?

 

[kinhell]

I was pondering whether to use trunking from the consumer unit to first floor level as its outside on the side of the house as our walls have insulation so would be difficult to pull through. It would be 4 metres of trunking and then run under the boards on first floor level coming out in the new utility straight into the new CU. Otherwise its a matter of trying find a way through the cavity insulation.

 

[davy_owen_88]

A big drill bit and a short length of conduit will get through the cavity no problem.

 

[Lectrician]

16 or 25mm split con would be my choice, fed from a sw fuse, not a way inside the original consumer unit.

 

[kai]

A pair of B16 radials, will be sufficient to feed the Fridge and Freezer respectively.