Originally Posted by

**GoldDigger**
Expanding a little on what kewired said:

For what it is worth, the NEC would be perfectly happy with the ungrounded conductors not being oversized in the first place, which would make the trip time even worse.

Another argument is that the voltage divider effect before the OCPD trips will make the momentary voltage on grounded surfaces higher than it would be if the EGC is also oversized. But since it would be at least one half of the line voltage anyway, I do not see that as particularly important.

If you take as given that a size increase for VD will only be done if the VD would otherwise be more than 5%, then the need to upsize the EGC to maintain low trip time does make sense.

If you upsize to reduce 2% VD to 1% VD, then the motivation to upsize the EGC iscbmnot nearly as strong.

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I see long runs on irrigation installation where even if EGC is compliant with the rules, there is still enough resistance that fault current is limited. Seen several instances where fuses never blow where they would have if long circuit lengths weren't involved. But this is often further complicated by the fact that 480/277 can sustain an arc fairly easily and that arc is also current limiting. Bolted faults should still blow the fuse, just may take a little longer than if there wasn't long conductor run.

I live for today, I'm just a day behind.

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