Versión en español
I found myself in need to move my noisy woodworking to my back yard to avoid waking up my lady who works night shift. I decided to wire my shed and after some homework and the help of the Instructables community I started my project. Before we start I assume that you know how to wire the different fixtures.
First you will need:
Step 1: The Right Conduit
The right conduit to use is a liquidtight conduit approved for use underground or outside installations. It is a metal conduit covered by resistant plastic. You should find out if there is a code regarding buried electrical lines. My conduit will be buried between 18" and 24". You do not need to worry about frost lines because you are dealing with electricity and not pipes carrying water.
I bought 50 feet of conduit, more than the distance between my house and my shed. The conduit will be connected to a switch box in my basement and to a junction box inside my shed.
You will need an electrician's fish tape to pull the wire inside the conduit. If you find difficult to pull the wire there is a clear lubricant that you can use to make the job easier. Make sure that the lubricant dries before you connect the wire to the main box.
Step 2: Wire
The wire that I got for this project was a type 12-2. It is the right wire for home wiring and for my needs in my shed. Make sure that the wire is inside the conduit before you start the installation.
I became aware that it is against electrical codes to use sheathed cable inside a conduit. Therefore you need to pull three unsheathed wires inside the conduit with a fish tape.
Black wire for the "hot" or "live wire"
White wire for the neutral
Green or uninsulated wire for ground
Step 3: Switch Box
The switch should be inside the house for safety reasons. If you need to turn off the electricity that goes to the shed, the wire underground outside the house will not be energized. Also you will be able to turn off the electricity when you leave for vacation.
One end of your conduit will be connected to this box. When all the wiring is safely installed you can wire the switch to your home electrical panel.
Step 4: Digging the Trench
I dug the trench to bury the conduit by hand ( I mean not literally but with a shovel). I dug for several days, taking my time. If you want to spend some money and rent a trench digger you can but money was an issue for me so this old man decided to dig the trench himself and do it at his pace.
I found a large rock while digging and I did not have any dynamite to blast it so, I patiently dug around it.
Step 5: Wiring the Shed
After I determined the best location for the junction box, I built a panel where I could keep everything together: the junction box, the electrical outlets and the light switches.
I drilled pocket joints in two pieces of 2 x 4 and screwed them to the supporting studs. Then I screwed a 3/4 inch board on the 2 x 4 's.
Step 6: Connecting the Circuit to the Switch and the Main Box
I selected one of the basement windows the entry for the liquid tight conduit. I drilled the hole in the window using a spade bit big enough for the conduit to go in. I connected the conduit to the switch box thus allowing me to turn the electricity off when on vacation.
Step 7: And There Was Light, and the Light Was Good!
Finally I can set my tools to work in or around my shed. My dear wife will be very pleased that I move my noise making to the backyard. A future addition will be an outside motion light. I hope that the information will inspire you to do the same and give ideas.