I'm installing a 50 amp sub panel to my detached garage being fed from 100 amp sub-panel. I'm using 4-4-4-4 aluminum. Do I have to keep the ground separate from the neutral if I drive a rod into earth?
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2 Answers
Neutral and Ground Must be Separate Except in the Main Panel
Period.
No exceptions.
The reason you are using quadplex cable is to separate neutral and ground. If you didn't need to keep them separate then you could save money with triplex.
The ground wire/rod is needed for "natural" electricity. The ground wire back to the main panel is primarily for wiring and device problems. Both are needed.
And it really is no big deal. That subpanel should come with a ground bar anyway. If it doesn't (e.g., a "main" panel being used as a subpanel, which is perfectly fine) then you can add a ground bar easily and inexpensively.
The 50A is determined by the breaker in the panel feeding the subpanel. With 4 AWG wires you can actually go up to 65A, provided you have enough capacity in the panel and the service. The building requires a disconnect, and you can use a separate disconnect (a $20 air conditioning disconnect will do just fine) or you can use a backfed breaker on the feed, or you can use a "main" panel that comes with a main breaker. You could put in a 42 space 200A main panel and use the 200A main breaker as the disconnect, because the 50A breaker in the feed panel protects the wires.
answered Aug 9 at 22:01
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YES.
Neutral and ground can only be bonded at the first panel(main) in the service.
Every other panel must have neutral and ground separate.
Detach buildings do need their own ground rods plus the ground to the feed panel.
