Electrical supply to extension

[paull123]

Hi
I am trying to save a few quid and do a lot of the work myself. I am not a noob but would like some advice.
At present I have a 10mm radial supply coming in to a kitchen extension from the consumer unit which was added by a qualified electrician in garage when extra work was done to house. It is round my ex partners house so without checking I assume it is off a 32 amp breaker. It is just a single wire which is obviously isolated. I want to install a ring main of 6 sockets and a separate radial supply for an electric cooker. Cooker will be a built in one, separate gas hob. I cant find rating of any to buy yet, I am right to guess at 2-3kw ?
So how do you go about it. Can I install a separate consumer unit with 2 RCD's in kitchen extension for the 2 circuits ? Too much work to run new cables back to old consumer unit.
I do understand that all work has to be certified and I would not make the final connection.
Thanks for any advice.

 

[sparkwright]

Assuming it is a 10 mm2 cable, ie the CSA of the conductors, it would seem reasonable to use that garage cable, though you may want to upgrade the MCB.

You will presumably need a lighting circuit too.

Smoke and heat detectors will almost certainly need to be added.

You WILL need to discuss all of this and more with the electrician doing the connecting up/certificates though of course.

 

[paull123]

Thanks for your reply. Lighting circuit is already sorted off existing board. Will this suffice ?
http://www.screwfix.com/p/lap-2-way-populated-rcd-garage-consumer-unit/6348g

 

[DaveHerns]

Not for a ring main and a cooker supply. What's in the garage and being fed by the existing supply?

 

[paull123]

Sorry Dave not made myself clear. Garage has been converted to a dog grooming parlour. Just a small ring main in there. My question is really how do you attach a ring main of 6 sockets and a supply for a cooker off a radial supply off a 32 amp circuit breaker from the main consumer unit ?

 

[sparkwright]

As said, best confirm the cable size to the garage first. If it IS large enough, you can THEN increase the breaker at the house end. A 2 or 3 way board in the garage would be suitable for the two circuits you need.

Typically the new board could consist of an RCD incomer, with two MCBs
or
A main switch with two RCBOs.

Size of the cooker would be handy, but I think you estimated 3 kW.

How do you know the cable is 10mm2?

 

[winston1]

If the supply is already RCD protected in the house there no requirement of need for other RCDs in line in the garage.

So after confirming cable size the next question to ask is if there is already RCD protection.