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I am going to create a grannie annexe. Our mains supply comes 150 ft under ground to our 12-way distribution box. We have a couple of empty slots. I want to supply the annexe off these. Can I put in a 60A mcb and run a cable to a distribution box in the annexe? It will have a cooker, immersion, ring main and lighting. Any advice appreciated.
I doub't you will get a 60amp BSEN60898 MCB. The biggest thats generally available is 50amp. What your suggesting will work, but it would be far better to spilt the meter tails using henly blocks and take either double insulated tails through the wall to a separate consumer unit for the annexe or run a XLPE SWA lateral from the henly blocks to the new annexe consumer unit.
Remember that Part P of the building regulations applies to this work, so you will need part P consent and pay your local authority fees (normally around £200 - £300). Failure to comply can result in a £5000 fine. (see link below for more info)
Answered 21st Feb 2013
I agree with Electrical Safety Services comments, personally i would interupt the meter tails with a henly block and run a suitably sized SWA (armoured cable) to the second distribution box.
The CSA (size) of the SWA would be determined by the maximum load required at the new distribution board.
If you employ a qualified electrician who is Part P approved they would inform the Local Authority on your behalf at a fraction of the cost - saving you around £200!!!
Hope this helps
Chris - Brightwise Electrical
Answered 23rd Feb 2013