Two Panels, One Facility

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Trey4U

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Alabama
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Retired Electrical Contractor
I have a 400 amp service panel on a building and right next to it a 225 amp sub panel that feeds small A/C units. The service panel has a ground rod and GEC, does the sub panel need to have a GEC connected to the rod? What Code article covers this? I think the equipment ground from the service panel is sufficient.
 
The GEC only connects to your main service panel in this case. Any subpanels downstream in the same structure would only have an equipment grounding conductor ran to them, but no GEC.

250.24
 
Trey4U said:
I have a 400 amp service panel on a building and right next to it a 225 amp sub panel that feeds small A/C units. The service panel has a ground rod and GEC, does the sub panel need to have a GEC connected to the rod? What Code article covers this? I think the equipment ground from the service panel is sufficient.
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250 parts II and III. Mostly part II tells you what must be grounded, part III mostly tells you how to install the GEC/GES.

You have a feeder that is not supplying a separate building/structure, it is already connected to the GES of the service or separately derived system that supplies it.
 
I vaguely remember reading a Code Article that specifically mentioned more than one panel at a facility. Anyone know where I might find that again?
 
Trey4U said:
I vaguely remember reading a Code Article that specifically mentioned more than one panel at a facility. Anyone know where I might find that again?
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There is 250.64(D) Building or Structure with Multiple Disconnecting Means in Separate Enclosures, but that is not what you have described your application to be. You have a service supplied panel and then a feeder supplied panel - in same building. You do need to install a GES for a feeder supplied panel if in a separate building
 
If there is more than one service panel then you cannot just connect to one panel. The other service panel would also need to be connected to the gec
 
Dennis Alwon said:
If there is more than one service panel then you cannot just connect to one panel. The other service panel would also need to be connected to the gec
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Only one service panel feeding a panel next to it and another inside. I figured the equipment ground to each sub panel was sufficient but thought there was a specific Code article addressing this.
 
The enclosure(s) that contain the main disconnect(s) is (are) where the GECs terminate to the neutral, the insulated-from-ground neutral begins, and the premises EGC system begins. Everything downstream is wired like you would a sub-panel, and the neutral should not be grounded again.
 
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