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G

Greg:

Can any one help re the regs/guidance regarding requirements for double pole switches in outbuildings (fed either directly from a breaker box or from a switched fused spur on a main building circuit)?

Looking at the following graphic
Outbuilding isolation? garage supply - EletriciansForums.net
(originally from iee? doc http://www.electriciansforums.net/a...ted-pme-outbuildings-garage-shed-supplies.pdf) the use of a DP isolator is indicated.

I'd gone further on a previously planned a garage wiring job specifying a main switch unit (into which mcbs for lighting and socket outlet could be fitted).

The client eventually went for a plan not using DP isolation in the garage but just to rely on isolation in the main building. I was told that the electrician cut into the panel of the fuse box so as to fit a breaker. I didn't see the result but presume some form of RCBO was fitted. The supply from the fuse box was then fed back into the outdoor meter box (again I didn't look inside) but I guess that, possibly, RCD protection could have been installed in here.

Anyway, presuming there is RCD protection in a main building, can a feed run straight into outbuilding accessories?

Second query,
The job mentioned had originally been planned with the feed coming into one side of the garage but with a planned socket outlet on the far side and with the garage lighting (not surprisingly) being placed in the middle.
If a feed was run straight into the in terminals of a switch fused connection unit for lighting could the feed to the socket be run from these in terminals? This would have kept the accessory count to two and kept the design in line with the clients wishes.

The pdf indicates a two way board being used in a garage on a diagram explaining garage feed straight from a main building breaker box. I was wondering, even if a two pole isolator switch were fitted (but just in a one gang accessory box as in the diag for feed from a main building spur) whether the lighting fused spur and the socket spur could simply be fed from the DP switch terminals.

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http://leweselectrical.co.uk
 
Last edited by a moderator:
Can any one help re the regs/guidance regarding requirements for double pole switches in outbuildings (fed either directly from a breaker box or from a switched fused spur on a main building circuit)?

Looking at the following graphic
View attachment 8317
(originally from iee? doc http://www.electriciansforums.net/a...ted-pme-outbuildings-garage-shed-supplies.pdf) the use of a DP isolator is indicated.

I'd gone further on a previously planned a garage wiring job specifying a main switch unit (into which mcbs for lighting and socket outlet could be fitted).

The client eventually went for a plan not using DP isolation in the garage but just to rely on isolation in the main building. I was told that the electrician cut into the panel of the fuse box so as to fit a breaker. I didn't see the result but presume some form of RCBO was fitted. The supply from the fuse box was then fed back into the outdoor meter box (again I didn't look inside) but I guess that, possibly, RCD protection could have been installed in here.

Anyway, presuming there is RCD protection in a main building, can a feed run straight into outbuilding accessories?
Yes it would just be another final circuit a final circuit that feeds an outside accessory, as if you had outside lights on a pole or a pond pump. Often if there is just a light wanted or a single socket required it could be a cheaper option that installing a garage CU

Second query,
The job mentioned had originally been planned with the feed coming into one side of the garage but with a planned socket outlet on the far side and with the garage lighting (not surprisingly) being placed in the middle.
If a feed was run straight into the in terminals of a switch fused connection unit for lighting could the feed to the socket be run from these in terminals? This would have kept the accessory count to two and kept the design in line with the clients wishes.
Yes why not. From your protection device into the FCU supply side then parallel out to the Socket. Then on your load side of the FCU to the light which will be fused down.

The pdf indicates a two way board being used in a garage on a diagram explaining garage feed straight from a main building breaker box. I was wondering, even if a two pole isolator switch were fitted (but just in a one gang accessory box as in the diag for feed from a main building spur) whether the lighting fused spur and the socket spur could simply be fed from the DP switch terminals. Yes the double pole switch in the diagram looks like it is a 20amp type and so as it is fed from a 13 amp FCU it would not have a chance to be overloaded

Answers in red
 
Thanks Malcolm for the positive post.
It seems that the regs say one thing and literature such as pdf quoted suggests the use of a larger quantity of equipment than required.


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http://leweselectrical.co.uk
 

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