Wire Derating - 30 Amps


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Old 03-17-14, 07:17 AM
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Wire Derating - 30 Amps

When wiring 30 amps for a generator, whether it be for the portable cord or the *inlet* run, am I supposed to derate and use 8 AWG versus 10.

All the *off the shelf * generator cables all seem to be using 10AWG
 
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Old 03-17-14, 08:32 AM
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You are not required to, however I usually try to.
 
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Old 03-17-14, 08:37 AM
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Axis of Overkill or not

The L14 won't work with 6 Wire
However, buy once cry one.

I've been thinking I might just pull 6/3-8/1 for the inlet.
I'll have to splice it to a smaller wire gauge for the L14.
Maybe to *some eyes*, it might look hodge-podged.

The bigger gauge wire will always be there, IF I need to upsize once more.

Bad Idea ?
 
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Old 03-17-14, 10:50 AM
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The portable line set is in free air.

Inside the house under 35' I use #10. Over that and I'll upsize to #8.
#6 would be overkill for a portable generator connection.

Derating comes into effect with more than three current carrying conductors.
 
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Old 03-17-14, 07:29 PM
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Also remember 30A @ 240v = 7200 watts. Many generators with 30A outlets are under 7200w running watts. Since derating is based on power (watts), it's rare that you'd need to derate to a larger than 10ga wire for a reasonably sized generator.

Unless you have a long run, I don't think it's worth upsizing the wire from the generator, especially with the termination issues you'll run into.
 
 

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