I am installing a single phase 18KW generator rated at 75 amps at 240 volts. Somehow I thought that the neutral would be rated to handle 70% of the rated output current, or about 52.5 amps, and therefore I would use #6 thhn wire per 310.16. Am I correct in my thinking? If not, can some nice soul educate me? Thanks to all who answer and have a blessed day!
Neutral sizing
- Thread starter RESI
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- Chapel Hill, NC
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- Retired Electrical Contractor
I would think that the generator neutral would be sized for the 18KW not 70%. Unless you have documentation that says otherwise I would assume 18KW.
Remember the calculated load on the neutral is probably not anywhere near 18kw so you can size the neutral to the load as long as the neutral is not smaller than the gec that would be required-- I think
Hopefully someone else will chime in
Remember the calculated load on the neutral is probably not anywhere near 18kw so you can size the neutral to the load as long as the neutral is not smaller than the gec that would be required-- I think
Hopefully someone else will chime in
445.13 Ampacity of Conductors.
The ampacity of the conductors from the generator terminals to the first distribution device(s) containing overcurrent protection shall not be less than 115 percent of the nameplate current rating of the generator. It shall be permitted to size the neutral conductors in accordance with 220.61. Conductors that must carry ground-fault currents shall not be smaller than required by 250.30(A). Neutral conductors of dc generators that must carry ground-fault currents shall not be smaller than the minimum required size of the largest conductor.
Exception: Where the design and operation of the generator prevent overloading, the ampacity of the conductors shall not be less than 100 percent of the nameplate current rating of the generator.
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