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Phil16 · May 22, 2009, 06:19 AM

I'm wiring an additional panel into a garage. It's connected to the Meter through a switch that switches the power between the company power and a generator. The main house panel is inside the house. I understand that the neutral and ground are connected in the "main panel" only and any subpanel would need these separated. Im not sure the additional garage panel would be a subpanel because it comes from the main power not the main panel in the house. Would it be safe to separate the neutral and ground in the new panel just to be safe? Is it okay to separate the ground and neutral bars in this new panel?

Stratmando · May 22, 2009, 06:33 AM

I would.

tkrussell · May 22, 2009, 06:35 AM

The connection of the neutral and equipment ground, called "bonded", only occurs at the service disconnecting means, AKA Main Breaker.

This breaker often is at the Main Panel.

The switch you refer to feeding this garage panel will act as the same as the main breaker, and the neutral and ground should be bonded there, and feed the garage with a 4 wire feeder consisting of the two hots, one neutral, and one equipment ground, and kept separate at the garage panel.

If the garage is detached from the building that has the main service, that garage panel will also need at least one 8 foot ground rod driven and connect to the equipment ground bar in the panel with #6 copper wire as the grounding electrode conductor.

Clear as mud?

stanfortyman · May 22, 2009, 07:38 AM

Originally Posted by tkrussell

The switch you refer to feeding this garage panel will act as the same as the main breaker, and the neutral and ground should be bonded there, and feed the garage with a 4 wire feeder consisting of the two hots, one neutral, and one equipment ground, and kept separate at the garage panel.

THIS is the key here.

True, the bond only happens at the main breaker/disconnect/panel, but there can be up to SIX of these. So it is entirely possible that the garage panel could be another main, and need to be bonded, IF it were not for the fact that there is a main switch ahead of it.

tkrussell · May 22, 2009, 08:32 AM

I understand, but don't all of the up to six mains need to be grouped together?

Esp if the garage is attached. Your scenario is for detached?

Just want to be clear for readers.

Seems to me in this case the main is at the meter, or should be.

New rule, everyone posts pictures with their questions. So many variables to think of.

stanfortyman · May 22, 2009, 09:31 AM

I see your point TK, and it is a good one.

I have seen and installed 320/400A services with a dual load meter with one panel in a garage/barn/shop and one in a house. I guess you could say each disconnect is grouped (by itself) at each separate structure.

It could be interpreted as a violation of 230.72, but could also be allowed by the final wording of 230.71.
We have always been allowed to do this, but like I said, your points are definitely valid.

KISS · May 22, 2009, 09:39 AM

Wouldn' that generator/house disconnect have a 3rd position of OFF. If it does then it really isw the first disconnect.

I also get the impression that is feeds both panels, again putting it as a single disconnect.

And, the neutral/ground bond shoud be made there.

Also, any idea if this transfer switch switches the neutral?
And re-stating: Does the transfer switch have an OFF position?