This is a guest post from the wonderful sheddie Andy over at Workshopshed.
An electrician is needed to install a Steel Wire Armoured cable in a deep trench to provide mains power in your shed.
Determine what electrical equipment you are going to use e.g. numbers of computers, workshop equipment, lawn mowers, lights etc?
Determine where you will want lights and sockets. It is likely that the cable inside the shed will require protection such as conduit or trunking.
Do you have special requirements such a weather proof sockets outside the building or machines that canâ€™t just be plugged into the mains?
Locate your fuse box; the electrician may have questions about it. It may need upgrading.
How far is the building from your home and how far is the fuse box from the exterior wall of the house?
Discussions with the electrician
Get hold of a competent person i.e. registered electrician who can complete domestic Part P Electrical Safety work. It is theoretically possible to do this yourself and get is signed off but the difference in cost/effort is unlikely to be worth it.
The electrician may need to make changes to your fuse box to support your new cable; this could include the addition of an RCB Residual Circuit Breaker; safety device that cuts the power in case of problems such as cut cables or damp) and an MCB (Miniature Circuit Breaker; a safety device that cuts the power in case of overloads and also acts as an on/off switch)
You will need to discuss the route of the supply cable with your electrician. Factors to consider will include: trees roots, flowerbeds, vegetable plots, driveways and paths.
The electrician will work out what size cable from your usage requirements and the length of the run. The more things you need to power and the further the distance, the fatter the cables need to be.
You need to dig a trench between the house and shed. Before digging, mark out with rope and use a spade or half moon tool to cut any turf. Stack this turf somewhere safe, it can be kept up to 2 weeks without watering. The trench needs to be at least 50cm deep and just wide enough for a cable.
For a short trench a drain spade should suffice, for a long trench you might want to consider renting a petrol driven trenching tool. The ease of this job will vary dependant on the type of soil as well as how many rocks and roots are present in it. The trench will be deeper under the flower beds and vegetable plots. It is quite surprising how much space you will need to keep all the soil, the looser and sandier your soil, the bigger the space you will need. Soil with lots of clay can be piled higher than sandy soil.
The electrician will route the cabling through the house, drill any holes in the masonry, terminate the cable at each end, and connect the cable to the fuse box via the MCB.
They will also fit your lights and sockets. They should provide a plastic tape to place over the cable warning people of the cable below.
Most importantly the electrician will supply a certificate of work which you will need when you come to sell your house.
Replace half the soil into the trench, bash it down with a wooden post and use a hose to water the soil. Donâ€™t overwater; you are not making a stream. Now replace the rest of the soil and repeat.
Place the turf back on the trench ensuring that you don’t leave gaps between the pieces. Leave it a week before mowing the lawn. If the grass dies or you have gaps then you will need to plant grass seed.
These instructions are based on my experiences in the UK earlier in 2008. If you live in a different jurisdiction or environment then these may not apply.