Salty Cajun Folks With Electrical Knowledge

[Reggoh]

Originally Posted by keakar

last I was aware, the electrical residential wiring code called for only 3 wires, two main wires and a ground wire (often slightly smaller sized) so this is why everything 220v "inside" the house is running off or 6/2 with ground or 8/2 with ground romex.

for safety they use an extra main wire connected to the exterior panel ground lug is why you need 3 main wires when running under ground out to a shed or separate garage? its just extra safety in case there is a problem with the grounding rod for the shed or garage.

The appliances in your home that you are talking about (hot water heater) are dedicated 220v and only require 2 hots and a ground... a sub panel in a garage or shop needs the 4th wire for a neutral so you can run 120v.

220v needs 2 hots and 1 ground
120v needs 1 hot, 1 neutral, and 1 ground

If you need help send me a PM... I'm not an electrician but I did stay at a Holiday Inn express last night.

(Just kidding... I am an industrial electrician so some of the residential guys may know a little more about code than I do but I'd be glad to help if I can)