"Quigs" wrote in message
om...
Can someone help me with their thoughts on shed electrics.

I want to run electric to my shed, and am planning to use 2.5mm SWA
cable so its protected. How deep should I bury it - I can do this
under a hedge so should avoid random spade attack etc.

I want to run 1 internal double socket, I IP55 external socket, 1
internal strip light and an external PIR light.

Real questions a-

1) What should the MCB rating be at the house consumer unit and should
it be RCD protected?

2) Do I need to add another consumer unit in the shed? If so what
should the maximum RCD rating be on this?

3) Should I add a local earth rod? If so what guage of earth wire
should I use to connect to it?

4) Is there an electrical book that I can read, that can help me with
this kind of question in the future?

Thanks

Quigs

If you use SWA cable for the supply, then try to go as heavy as you can
without being over the top. If you use a two core SWA with 6mm conductors
from the house and have it protected with a suitable breaker, 45amps will do
it, within the consumer or sub-mains switch, then you can really take the
supply as dealt with and safe for anything, other than welders and massive
heating elements, you want to fit and work with in the shed. Burying the
cable is the one thing people don't usually do properly and the only advice
I give them is to bury it as far down as possible so it doesn't get dug up
again accidentally. And that doesn't mean by you because you know it's
there, it's also by other people who might live in your house after you do.
Having power into the shed is also a great selling point remember.

Within the shed itself you should have a consumer unit with enough ways to
take a small ring mains circuit protected at 30amps for wired fuses, or
32amps for an MCB breaker, and run your sockets from this. A lighting
circuit will be protected by a 5amps wired fuse, or 6amps MCB breaker,, and
this is enough to run even halogen security lights from if you wish. It's
also a good idea to have an all weather socket low down beside the door and
separately fused from the other circuits and can be used for all manner of
things in the garden.

Always make the system separately earthed from the house circuits, but this
doesn't mean separating the bonding on the SWA cable between the two points.
Use the house earth to protect the outer skin of the cable between the two
consumer units, but have a separate earthing rod into the ground locally to
the shed and connected directly to the earthing bar in the shed consumer
unit. It doesn't interfere with any of the systems proper working profiles
and just gives the added local protection needed for this type of
installation. Make sure that the impedance between the rod and the ground
is as low as humanly possible, so this night mean you have to bang in a two
metre length of 15mm copper pipe to have a proper protective local earth.