I have a shed that I am using as an office. Since everything that I will need to power (lights, computer, space heater) are already being powered by an extension cord to an outdoor outlet on the house, I won't need a subpanel, and I would like to simply extend the power from an existing 15 amp circuit running along the exterior wall of the house (either from the indoor circuit or outdoor outlet). What do I need to do in order to wire this up to code? I can't run a dedicated circuit because I don't have room in my old service panel in my house.
Update:
The distance from house to shed is about 30 feet or less. The extension cord that I'm using is probably only 16 gauge. The space heater that I have been using is a small 500W. But I recently started using an additional 1500W (two heaters, 2000W combined). I assumed that if it was drawing too much power it would have tripped the circuit breaker, but it hasn't. I don't want to install a subpanel or mess with the main service panel due to the difficulty of running a new circuit from the outside of the house to the inside service panel. I don't mind using a larger conduit to make it easier to run new cables in the future if necessary. The main goal right now is to extend an existing circuit as easily as possible while remaining code compliant so that I can get the inspection done, add insulation and cover up the walls.
Here are some photos of my current service panel:
Best Answer
If you want to tap that circuit, get a box extension that has 1/2” conduit entrance. Most locations will require a “bell box” extension something like a 5400-0 . This brings the existing box out so you can connect conduit to the box and bury it and come up in the office. You will need the conduit from the box down the wall into the ground to burial depth. Depending on the distance and work to bury rigid conduit may be best, only need to bury 6”, if you use pvc 18”, or go with underground feeder / direct burial. If using conduit you will need a thhn/thwn wire type almost all thwn wire is dual rated thwn. With a 15 amp circuit 14 awg wire is needed. There are other ways to tap into circuits but a box extension at an existing location is the easiest. If this is the circuit you are using now you know it will hold for the loads because you are using it now. You will need GFCI protection on the receptacles.