Subpar voltage in 220V Receptacles? Three Phase Building.


Old 02-27-19, 10:48 AM
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Subpar voltage in 220V Receptacles? Three Phase Building.


We have x4 220v plugs in our 3phase building, all powered by Two-Pole breakers in their respective subpanels. Across the board, between the two hots, I measured 209v. At minimum, 220v should be acceptable, yes?

I tested a good 119-120v for each individual hot to neutral.I find it odd that I tested all four I could find and they all consistently measured 209v.

One of the receptacles I tested is on another sub-panel, which makes me feel like the problem is over-aching over the whole building.I did not test the lugs in the subpanel yet - but will. What other steps can I do to diagnose? What would be the cause of this?

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Old 02-27-19, 11:38 AM
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There is nothing wrong with your building. 208 is the standard voltage in a 3 phase system.
Old 02-27-19, 11:38 AM
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Often in a 3 phase building you have 208 voltage, In the U.S. it is 240 (single phase) or 208 3 phase. We do not have 220v nominal voltage. Equipment incorrectly labeled 220 is really intended for use on 208v or 240v,
Old 02-27-19, 11:47 AM
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208V & 120V are the correct voltages in most commercial buildings on three phase service.

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