||11-11-2008 11:46 AM
Originally Posted by BenJoeM
I am getting ready to install a garage sub panel. I had a couple of questions.
I am adding a 60 amp sub panel off of my 200 amp panel. The question I have is about running the wire. I am running a #6 (or should it be #4) wire from the main panel (with a 60 amp breaker) to the sub panel. I had planned on running it in PVC conduit to the edge of the house and then going underground to the side of the garage, back in using PVC conduit up into the box. two questions:
1. I read that the depth of the underground conduit needed to be at least 18 inches for PVC. Is this correct? Does it matter?
2. If I am grounded at the main box on the side of the house, do I need to re-ground when I get to the garage? The main box is where I am running the power from.
#6 is fine for THHN/THWN. Not for UF (direct burial).
Using conduit is IMO the best way to go. Yes 18" is correct for the depth. You need four wires. 2-hots 1-neutral and one ground.
You need to drive at least one ground rod at the garage near the panel. You will install a bare #6 from the rod to the grounding bus terminal strip in the sub. You will keep the grounds and neutrals separate. You will use a disconnecting means at the garage. A main breaker sub panel will do the job for you.
Run a green ground wire with the other three wires. Terminating at the neutral/ground bar in the main panel and the ground terminal strip in the sub.
Make sure the wire is rated for wet locations. THHN and THWN are usually rated the same. There must be a "W" in the wire description.