I am looking at running conductors for a 20KW air cooled generator. The max. output on the unit is 83A, the factory breaker on the unit is 100A. Taking into account 75 deg. terminations would #4THHN be acceptable or would it need to be #3? This is a residential application.I'm told this same brand unit used to have a 90A breaker, but in the last couple years the manufacturer switched to a 100A. FWIW, the total connected load to this gen set will be approx.60A. Thanks.
20KW Gen hook up.
- Thread starter nizak
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The branch circuit rating is determined by the overcurrent protective device (210.3), so with a 100 amp breaker you have a 100 amp circuit regardless of the 60 amp load.
If you are talking THWN, #3 would be required. With NM (and possibly SE) you are looking at a #2.
If you are talking THWN, #3 would be required. With NM (and possibly SE) you are looking at a #2.
goldstar
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- New Jersey
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- Electrical Contractor
I agree with Augie, # 3 is the right way to go. You have to size the wire to the breaker not what the connected load will be. Not sure if you'd void any mfr's warranties but if you change the breaker to a 60 amp you can then down size the wire. But then you have to ask yourself, why would I install a 20KW unit in the first place.
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