# What kind of wire would i need to carry 20 amps 100 feet underground

Have an existing underground circuit that goes from the house to the end of the back yard. It's about 40 years old, and I have no idea what shape the wire is in, but it still works. I'm thinking about build a shed at the end of the yard to use as a woodshop. I don't want to actually wire the building up, but I was thinking of running a new line underground. What would I need to run a 20 amp line around 100 feet underground.

• 100ft underground? 30M? That is quiet the hole you are digging. You sure you don't mean 100cm? 100cm is doable (barely) with a trench digging shovel (in the right soil, if you are lucky). 100mm seems reasonable. 30m is some serious earth moving Commented Sep 15, 2016 at 6:04
• @Oxinabox, I think it's safe to assume he means 100' linear feet, not 100' deep. Commented Sep 15, 2016 at 11:44
• You say a "20A line", but what is the load? Commented Sep 15, 2016 at 11:44
• @SpeedyPetey ooooooooooooooooooohh that makes more sense Commented Sep 15, 2016 at 12:17
• Yes I mean underground, for 100 feet, not 100 feet underground .... and 110 volts not 220 Commented Sep 15, 2016 at 18:57

## Wire size

You can use a calculator like http://wiresizecalculator.net/ to figure this out.

Keep in mind that the distance is not just the distance underground, but the entire wire distance from the panel to the receptacle/switch/fixture.

For 140', you'll need #6 copper or #4 aluminum.

## Burial depth

For a 120V, 20A circuit, protected by GFCI, in residential use, using direct-burial rated wire (UF), the minimum depth requirement is 12".