Help a poor student whose hand in is tomorrow!!!

[lazy student]

Cheers Shanky, if carrying capacity is 13.5 A and i've got two 13A sockets and i run a ring final should i use a 25 A MCB?

 

[shanky887614]

no mate. by 13amp socket its the max it can pull.


let me respond to your question with a question.

if your house has 2 ring circuits on 32amp mcb's. a 60amp cooker mcb and a 32amp shower circuit.

why has it only got a 100amp incoming fuse?

its all to do with diversity mate

(type b mcb's come in 6,10,16,32, etc)


remember the mcb is to protect the cable not the device.

i recomend you buy the onsite guide and have a read through it

www.amazon.co.uk/gp/aw/d/1849192871/ref=mp_s_a_1_1?qid=1370374964&sr=8-1&pi=SL75

 

[lazy student]

Cause none of them are expected to pull their max. so i just need enough to protect the cables 16A MCB?

 

[telectrix]

CCC of 2.5mm in conduit , ref. method B , is 24A so a 20A MCB would be appropriate.

 

[lazy student]

brilliant thanks telectrix

 

[Outspoken]

As a reference for both you and your tutor I would refer you to Appendix 15 of BS7671:2008 Ring and Radial Circuit Arrangements : Regulation 433.1 on pp425.

Regulation 433.1 in the title of the Appendix directs the reader in pp81 and specifically 433.1.103, I strongly suggest you read it before proceeding and ensure you understand it.

 

[lazy student]

Ok having got a copy of the regs (don't ask how i did that at 11pm), I think the problem arose because I had forgot that the circuit is "unlikely to exceed for long periods of time the current carrying capacity of the cables" (433.1.5)

Cheers for all the help gents

Lazy