Fire Pump w/ On-Site Standby Generator as Alternate Source

[infinity]

I have a fire pump with two power sources, one a feeder supplied by a disconnect switch with a tap before the service disconnects and the other by an on-site standby generator as the alternate source. The feeder disconnect is sized and fused at 600% of the fire pump FLA. Should the disconnect/OCPD for the alternate source also be at 600% or would normal motor rules apply? I've been perusing Article 695 but I haven't found anything conclusive.

 

[hillbilly1]

Some engineers will have you tap ahead of the main on the generator, but if I remember correctly, with backup generators, it is not required. You are required to have enough capacity to start and run the fire pump which may mean load shedding other non critical loads.