If it is a detached garage it needs its own main breaker/disconnect 225.30 (Some AHJ's require this be on the exterior), and a EGC going back to the main house panel in addition to the grounding system at the garage. 250.32(A)
Mark Stetson Stetson Electric
Re: Sub in Garage#39406 06/19/0412:39 AM06/19/0412:39 AM
Check for the fire wall rating, some local codes will require a 1, or 2 hour rating for a wall from a garage to dwelling space. Condo's especially! So in this case your openings would need to be of a certain (small TBA) size. Depanding on the fire code. Or you'll have to go with a surface panel. In some cases like this I'll have the general put up the rock where the panel will be, put a 14x14x4 box above it, stub all the cable evenly in a pattern into the back of it. (2 for larger circuit counts) Then a 2 1/2" nipple into the panel. This way, it's a pattern of small holes, (that you can feed and chalk from the back) as opposed to a 14x36" hole. Theres nothing sillier than a rock box, and chaulk for a panel!
I put cans in cieling that i didn't know was going to be fire rated once, boy was that a mistake!
Mark Heller "Well - I oughta....." -Jackie Gleason
Re: Sub in Garage#39408 06/21/0404:22 PM06/21/0404:22 PM
Techgod, a separate EGC is not needed from the house to a detached garage as long as there are no other metallic connections between the two buildings (TV, phone, water pipe, etc...). However, I personally would never run only three wire for a detached garage (I doubt that any licensed/informed electrician would).