generator wiring

angler3November 4, 2012

i just purchased a 5500 gen.. shop told me to use 20 amp outdoor box with 20 amp twist. they were out of 30 amp boxes. they told me that it can handle the 30 amp... i am using 10/4 wire with a double breaker rated for 30. my concern is will the 30 amp melt the 20 amp outdoor box. they told me the wiring and size of prongs are the same, the layout is different to distinguish amps. Is this safe and true.

thanks for any help.

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Ron Natalie

Salesmen are by and large:

1. Ignorant
2. Will lie to make a sale.

    Bookmark   November 5, 2012 at 10:05AM
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So the wire from the generator to the 20amp twistlock can handle 30amps. The wire from your 20amp outdoor box back to the breaker panel can handle 30amps. The only things rated 20amp are the twistlock and box. Since the prongs are indeed the same size (different orientation), you might believe that you can get away with it. However, inside that 20amp twistlock receptacle, there may be smaller pieces of copper between the female slots and the screws. Can they handle more than 20amps? I doubt it. That's why they make 30amp twistlocks.

Will it instantly melt if you push 21amps through it for 5 minutes? Probably not. 28amps for 12 hours? Might have a problem.

If you are backfeeding your generator into your breaker box (which I think that is what you are doing), that is very dangerous. It relies on you cutting the main to prevent backfeeding to the pole (and killing your friendly lineman trying to get power back to your house). Try as you might to always remember, you continue to see reports of home owners and linemen getting killed (or worse) with people backfeeding a generator via a plug and breaker.

    Bookmark   November 5, 2012 at 2:54PM
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