Proposed wiring for workshop

[rikdogguk]

Hello

I would like to install an electrical supply to my workshop and would appreciate thoughts.

The workshop is around 10 m from the house. I require 2 double sockets and lights.

The CU in the house is RCD protected. There is already a non-functional "garage" circuit with a 32A MCB. This circuit comprises a single live 4mm2 twin and earth cable which is currently terminated in a JB inside the house - the garage was demolished before I bought the house, it seems this is how the electrical supply was disconnected.

My intention is to run a 4mm2 three core SWA cable between the house and shed, in a trench at 500 mm depth. The cable will be in a duct. Warning tape will be placed on top of the duct with a marker layer of sand prior to backfilling.

The existing junction box in the house will be replaced with a suitable metal box - the SWA cable will be terminated in this box and connected to the existing 4mm2 garage circuit.

Workshop side, SWA cable will be terminated in a 32A double pole switch. Sockets will be connected off this in radial circuit. Lighting circuit will be spurred off a socket using a 3A FCU.

I appreciate that if the MCB / RCD trips this would necessitate entering the house to reset, but I dont see this as being too much of an issue (bar a mild convenience).

Does this seem ok?

Thanks, Richard

 

[Simon35]

I would have a double pole switch at the house end, so that if you have any faults on the SWA which trip the RCD, you can isolate it and keep the house power on.

Earthing nuts are easier for the layman than banjos on SWA glands.

Testing?

 

[ban-all-sheds]

I appreciate that if the MCB / RCD trips this would necessitate entering the house to reset, but I dont see this as being too much of an issue (bar a mild convenience).

You might not, but others in the house might disagree, particularly if any problems with damp make it a recurring event.

I would have a double pole switch at the house end, so that if you have any faults on the SWA which trip the RCD, you can isolate it and keep the house power on.

Testing?

 

[rikdogguk]

Good point, a double pole switch in the house sounds like a sensible addition.

Testing - I will look into this.

 

[ban-all-sheds]

A good intro: http://www.tlc-direct.co.uk/Book/8.1.1.htm