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https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl DIY Forum >> Electrical Questions >> 2nd shed sub CU, main switch required? https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl?num=1244797429 Message started by MikeGB on Jun 12^th, 2009, 10:03am

Title: 2nd shed sub CU, main switch required?
Post by MikeGB on Jun 12^th, 2009, 10:03am

Shed 1 has 6mm swa from 40 Amp mcb (non rdc side) in house CU into shed 1 CU main 40 amp 30mA 2 pole rcd protecting all sub circuits.

32 amp mcb in shed 1 CU feeds to shed 2 via 6mm swa into 4 way enclosure with 3 ways used 2 x 6 amp and 1 x 16 amp mcb's.

Do the regs require to have a double pole means of isolation in this 2nd shed or can I just attach an "Isolate elswhere" label to the adaptable box that the swa enters the enclosure via?

I dont think it makes much difference but the sheds are right next to each other.

Title: Re: 2nd shed sub CU, main switch required?
Post by Lectrician on Jun 12^th, 2009, 11:15am

It is a difficult one to call in some respects.

For the price of a dinrail mount double pole isolator, I would fit one anyway.

Title: Re: 2nd shed sub CU, main switch required?
Post by MikeGB on Jun 12^th, 2009, 11:52am

Well if it was that simple I may have just done that :-) but the enclosure is 4 ways (singles) so with 3 used its a case of a new enclosure as a switch will take 2 ways.
No requirement under 17th that you know of that says you must have the switch then? If so I will just go with the label.

Title: Re: 2nd shed sub CU, main switch required?
Post by Y3 on Jun 12^th, 2009, 5:48pm

Your point of isolation is effectively the main switch, or the 32a CB in shed one?

Title: Re: 2nd shed sub CU, main switch required?
Post by MikeGB on Jun 12^th, 2009, 7:22pm

The point of isolation for shed 2 would be either via the supplying 32amp mcb in Shed 1 (live feed only) or via the main switch in Shed 1 (both poles)