Sizing Generator feed

[ScottA23]

Can a 1200 amp generator feed a 3000 amp transfer switch?
Normal feed is 3000 amp from the Utility, the load is also 3000 amp.
I was told the NEC code doesn't restrict feeder sizing based on panel rating.
Where is this in the NEC code?

 

[Dennis Alwon]

You can if the transfer switch is manual. If it is an automatic transfer switch then the generator must be able to carry the entire load

 

[ScottA23]

Do you have a code reference for that?

 

[hillbilly1]

Its more of a design issue, yes, if automatic, it must be able to carry the full load, but that doesn't mean it has to be 3000 amps. It can be done several ways, one, is automatic load shedding, such as an energy management system, or even an electrical interlock. The ocp in the generator dictates its feeder size.

 

[texie]

Do you have a code reference for that?

If the load is 3000 amps how is it gonna work if the genset is only 1200 amps? Do you have automatic load shedding?
The code will vary on whether this is a 700, 701 or 702 system. See .4 in each Article.

 

[LarryFine]

Normal feed is 3000 amp from the Utility, the load is also 3000 amp.

Highly unlikely. Is the load 3000a or is the service rated at 3000a?

 

[tortuga]

Do you have a code reference for that?

If your talking optional standby system your reference is 2020 NEC 702.4 (B),
Legally required 701.4(B)