Auto Switch Generator and Main SE Panel Grounding


Old 09-17-18, 10:46 AM
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Join Date: Sep 2018
Location: USA
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Auto Switch Generator and Main SE Panel Grounding

I'm installing new service for a new addition I have built. I have a whole house generator that feeds a 200 amp auto switch. The switch is wired between the service entry meter and the main service panel, all of which are new installation. Main service power is not yet connected to the new meter base. Today the electrical inspector told me that my main service panel must have ground and neutral unbonded and fed with 4 wire service as it a sub panel from the auto transfer switch. This doesn't make sense. Only the hot are switched by the auto switch, ground and neutral are bonded within the auto switch. We are under the 2012 NEC rules at this location and the sections governing generators is not even close to being clear.

I disputed making my main SE panel a sub panel with the inspector and old him I would research more.
Old 09-17-18, 12:15 PM
Join Date: Mar 2010
Location: USA
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Ground and neutral are properly bonded at the first location where there is a whole house disconnect of the hot supply conductors. Unbonded everywhere downstream.

The whole house transfer switch upstream of your primary breaker panel is now "the main panel" if there was not yet another whole house disconnect further upstream say at the meter.

Your primary breaker panel has now become a subpanel and needs the fourth conductor as a ground coming down to it.

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