I had the builder install a box on the back of my house for my future building. Now that we have settled in I now have the building put up and dug the trench for the electrical. When I removed the cover on the preinstalled box I found two 12/2 sets of wires. I called the electrician and he checked to find out both wires lead to the one breaker in the main panel. He said I could get a tandem breaker but I thought it was their job to do it right. I have learned that it should gave been 10/1 or larger gauge installed but the wire cant be pulled and replaced. Can I have both wires somehow run to the building to get two 20amp feeds. Help!

 

Can only have one feed.
What do you plan on using this building for?
12-2 would be way undersized for anything but a light and a couple outlets for light loads.

 

(Terminology: cables not wires. Wire is a single conductor. Cable is two or more wires in a metallic or nonmetallic sheath.)
Only as a multi-wire circuit. Code forbids more than one source of power. You can use a multiwire circuit to provide two 20 amp circuits because by code that counts as a single circuit but you can't use two 2-conductor cables because by code all conductors must be in the same raceway (sheath or conduit). One twenty amp circuit is all you can do.

No such critter. Did you mean 10-3 cable.

Did you ask him if he got his license from a Crackerjack box? A newly installed panel should not be so full you need to use tandems*. Seriously is this a general contractor or a licensed electrician? If GC do you know if he had a licensed electrician do the work? Were permits pulled and approved? While it wouldn't have affected the would be shed wiring it makes me wonder about competence.

Joecaption1 wrote:
I disagree. Most sheds are well served by a single 20 amp feed but we will not know till you answer Joecaption1's question on usage. What will you have out there? Abandoning one cable could be the best answer for your situation.


*Please post a picture of your breaker box with the door open. http://www.doityourself.com/forum/li...-pictures.html