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Tuesday, December 14, 2021

Question:

Hello CQD,

In reference to NEC 250.122 (B), as it applies to increasing conductor sizing to compensate for voltage drop, it states that the grounding conductor shall be increased in size proportionately to the increase in circular mil area of the ungrounded conductors. The ratio from ungrounded and grounded conductors, to the grounding conductor is one to one for 15, 20, and 30 amp circuits. For example the ungrounded and grounded conductors in a 120-volt, 20-amp circuit are increased from #12 to #6 to compensate for voltage drop. Would the one to one ratio #12 grounding conductor also have to be increased to a #6?

Dennis Dipascuo

A

Answer:

Hello Dennis,

Thanks for the question. The equipment grounding conductor has to be adjusted in size proportionately to the adjustment in size of the ungrounded conductors when addressing voltage drop situations. In long runs, current what goes out must be able to return on an effective ground fault current path, without the impedance due to under sizing.

Hope this is useful.

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