Generator Inlet Vs. Back-fed CB

[infinity]

Say you have a 50 amp generator inlet with #8 MC cable are you required to use a 50 amp back-fed circuit breaker or can it be smaller say 30 or 40 amps? Unless I'm missing something it seems like the NEC is silent on this.

 

[480sparky]

The NEC is not silent on this. It's covered in 310.15.

 

[infinity]

The NEC is not silent on this. It's covered in 310.15.

There is no section in 310.15 that uses the word inlet.

 

[480sparky]

There is no section in 310.15 that uses the word inlet.

It won't because it discusses conductor ampacity, not device ampacity.

 

[infinity]

It won't because it discusses conductor ampacity, not device ampacity.

You lost me.

 

[480sparky]

Putting #8 on a 30a breaker is perfectly legal, no?

 

[infinity]

Putting #8 on a 30a breaker is perfectly legal, no?

Yes of course I'm just wondering if there is any requirment when using a 50 amp inlet to be feeding a 50 amp CB at the panel. I don't think that there is or at least I cannot find it in the NEC. They have a 30 amp output on the current generator but may want to upgrade in the future to a large genny so I suggested using a 50 amp inlet, 50 amp conductors, and a 30 amp CB at the panel until the time comes that they upgrade.

 

[480sparky]

If you have the inlet and back-fed breaker and premises wiring all rated for 50, but only a 30a breaker on the genny, you're still good. You have everything protected by that 30a breaker. Upgrade the genny later to one with a 50a output, and you won't need to do any rewiring.

 

[Eddie702]

If you have the inlet and back-fed breaker and premises wiring all rated for 50, but only a 30a breaker on the genny, you're still good. You have everything protected by that 30a breaker. Upgrade the genny later to one with a 50a output, and you won't need to do any rewiring.

I agree

 

[infinity]

If you have the inlet and back-fed breaker and premises wiring all rated for 50, but only a 30a breaker on the genny, you're still good. You have everything protected by that 30a breaker. Upgrade the genny later to one with a 50a output, and you won't need to do any rewiring.

I agree, set it up now for the 50 amp inlet.

 

[jap]

I agree, set it up now for the 50 amp inlet.

What are you using for an interlock at the panel to coincide with the back fed breaker being installed?

JAP>

 

[Rock86]

What are you using for an interlock at the panel to coincide with the back fed breaker being installed?

JAP>

That was my first question while reading this.
also... remember the circuit breaker is only protecting down stream... it doesnt care about what is coming in as long as the conductors are rated.

 

[infinity]

What are you using for an interlock at the panel to coincide with the back fed breaker being installed?

JAP>

Probably something like one of these from the website Dennis recommended.

Manufacturers | GenInterlock