portable generator wire sizing

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Stevenfyeager

Senior Member
Location
United States, Indiana
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electrical contractor
The most common size portable generator around here is 5000 w. The plug outlet on the generator is usually 30 amp twist type. I run 10-3 from the generator inlet to a 30 amp breaker using a 'geninterlok' kit. Just checking, is this what you do ? Thank you.
 
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Yes that is fine and probably it's the most common (30 amp-inlet, conductors, and CB) setup used for connecting a portable generator to a home. Don't forget the Article 702 required signs at the inlet and the panel.
 
Stevenfyeager said:
Thank you. My customer is now looking at buying a 7000 w geenerator. Is my set up ok for that ? (7000 w/240 v = 29 a)
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I would guess that it's fine. You would need to know the size of the output CB and receptacle on the generator. My 8500 watt Generac has a 30 amp output and connects with a L14-30 cord set.
 
For my own home I used a 50A inlet and breaker. The generator has a 30A outlet and 22A breaker.

The generator will protect itself and the 30A cord. The 50A inlet provides room to expand.

Parts not much more expensive, labor is the same.

Jon
 
Stevenfyeager said:
And you also ran a #10 wire like I did ?
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#10 conductors are all that you need for a 30 amp installation unless you feel that voltage drop may be an issue.

Like Jon I actually installed a 50 amp inlet with #8 conductors for possible future expansion. (y)
 
NM, MC, and other 'building wire' cables don't include the EGC in the count. SO and other portable cords do.

Receptacles and plugs are described as X poles/ Y wires. X does not include the EGC Y does.

So for a residential single phase generator install you would have 10-3 NM to a 3 pole 4 wire inlet, then to 10-4 SO cable to the generator.

Jon
 
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