I want to extend a circuit from my house to my shed / shop. I need to run this extension underground. Can I purchase a wire capable of being buried without conduit or should I plan on running the wire in conduit?

THANKS!

 

Most people would just buy UF-B cable. This cable can be direct buried. If you GFCI protect it (by running it through a GFCI receptacle in the house) before it goes underground, it only needs to be buried 12" (the GFCI in the house will also fulfill the requirements for GFCI protection out in the shed). You probably need to buy a short section of conduit to protect the cable where above ground and until it reaches the bottom of the trench. Code only allows you to run one such cable to an outbuilding without a subpanel. 12/2 UF-B is probably what you want, protected by a 20-amp breaker in the main panel. If the distance is over 100 feet, you need to start worrying about voltage drop.

 

A practice worth considering is to use a multiwire branch circuit to supply the shed. By doing that you will lessen the voltage drop whenever both circuits are in use and you will double the power delivered to the shed without needing a sub panel in the shed.
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Tom