Load Bank Overcurrent Protection

[dinos]

If I have a 750kW, 480VAC load bank (902.5A full load) supplied by 4 sets of 350MCM copper conductors (1240A ampacity), does the upstream breaker have to be set no higher than 900A, or can I go as high as 1200A?

 

[infinity]

The NEC doesn't define the use of load banks directly. I would guess that you would size the conductors at 125% of the maximum load and size the OCPD according to the conductor size.

Good question.

 

[texie]

If I have a 750kW, 480VAC load bank (902.5A full load) supplied by 4 sets of 350MCM copper conductors (1240A ampacity), does the upstream breaker have to be set no higher than 900A, or can I go as high as 1200A?

I assume this is a resistive load bank. I would be inclined to use a breaker value of 125% of the load bank rating, pending manufacurer approval. Load banks I am familiar with usually have a control box for sub dividing the load into smaller chunks thru fuses and contactors for control of load and a set of lugs for the branch circuit connection.