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Commercial Subpanel Question


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I performed an assessment on a commercial building built in the 50?s and used as a sign shop. It has two subpanels fed with 3 conductors each. One has no separate neutral and the other no separate ground running back to the main panel.

I know the IRC states (I?m paraphrasing) a subpanel must have a separate neutral running back to the service disconnect which requires the subpanel to be supplied with 4 conductors: 2 insulated ungrounded conductors, 1 insulated neutral, and a bare ground (or sometime a metal raceway). I also know the IRC does not apply to commercial buildings. So I guess my question is "is this still wrong?" and what standard covers commercial buildings? Would you write it up the same way you would in a residential building?

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If there's no 120 volt loads then a neutral is not needed.

Got to have that EGC on both subs. If the feeder is within RGS - rigid galvanized steel - conduit then maybe you don't need an EGC conductor.

My state and I don't use the electrical section of the IRC, just the NEC.

Marc

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If there's no 120 volt loads then a neutral is not needed.

Got to have that EGC on both subs.

My state and I don't use the electrical section of the IRC, just the NEC.

Marc

Each panel has 120 v circuits, mostly 20 amp circuits.

It has 120 volt loads and there's no neutral? Must be an issue with semantics. Did you mean it has a neutral but no separate EGC?

Marc

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If there's no 120 volt loads then a neutral is not needed.

Got to have that EGC on both subs.

My state and I don't use the electrical section of the IRC, just the NEC.

Marc

Each panel has 120 v circuits, mostly 20 amp circuits.

OK then they are both 120 volt subpanels? That might not be a problem if the grounding is correct. It sounds like an electrician should check things over regardless. Antique equipment.
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