Domestic Shed Installation

[LGRSol]

Hi All,

Having recently qualified as an electrician, I am beginning to understand the adhocs and curveballs that customers can throw at you.

Last week I went to quote for a shed installation. The shed is approximately 25m from the property and would be a relatively straight forward notifiable job i.e. SWA buried to a safe depth (500mm), 2 way DB in shed for 1 way lighting and ring final sockets.

Now in my limited experience, as far as I am concerned the install would be directly to the main DB and either protected by a 30mA RCD or alternativly using an RCBO. However the customer has said that they really want the source to be from a fused spur out of the ring final circuit in the garage.

Obviously I am fully aware of the regs and in particular 5.7 of Part P. As far as I am concerned, this is an absolute no go, however I am struggling to find if this is stated anywhere in the wiring regs. Before I say this to the customer please could I have some advice / thoughts.

Much appreciated,
Lee

 

[gazdkw82]

A 4mm radial seems overkill for a shed.

Ring circuits have advantages in some situations, particularly in supplying a large number of sockets in multiple rooms of domestic premises where they are more economical.

To rule out one installation method over another based on opinion is narrow minded.

Could be overkill but it gives more scope in the future for added equipment. All depends on what's being used.

Could do A3 radial. 20mcb, 2.5mm.

Narrow minded? Most decisions are based on facts and opinions. IMO rings have more disadvantages than they have advantages. It's fact radials are easier to install and less complicated to test/understand.

 

[Leyland30]

The iet released a wiring matters document (google) detailing the use of a spur from ring circuit to serve an outbuilding - accepted arrangment subject to the considerations already mentioned by other posts.

You may also want to consider the distance of the shed from the origin of the supply. The greater this is, the stronger the case for a dedicated earth at the shed end I.e. TT arrangement. Presumably there are no metallic services entering the shed e.g. gas/water pipe work.

 

[Leyland30]

The iet released a wiring matters document (google) detailing the use of a spur from ring circuit to serve an outbuilding - accepted arrangment subject to the considerations already mentioned by other posts.

You may also want to consider the distance of the shed from the origin of the supply. The greater this is, the stronger the case for a dedicated earth at the shed end I.e. TT arrangement. Presumably there are no metallic services entering the shed e.g. gas/water pipe work.