Sharing

[hhsting]

I have one generator with two breakers one that feeds switchboard feeds three ATS: life safety, legally required, optional and second breaker feeds fire pump. Can one generator share building loads life safety, optional standby, legally required with fire pump or two separate generators are required? Any other codes or NEC 2017 addresses that?

I had similar questions previous threads but they were not about gen sharing itself

 

[don_resqcapt19]

See 700.4(B) and 695.3(D)(1). You will have to have enough generator capacity to supply the Article 700 loads, the Article 701 loads and the fire pump at the same time. Remember that the fire pump has to be able to start and you will have to have enough generator capacity to do that, even when it is supplying the other loads.
This is a design issue far beyond any plan review.