517.31(D) vs 700.4 & 701.4

[m sleem]

Referring to generator sizing, i think hospitals have the toughest design requirements compared to other applications, but in 517.31(D) the requirements of generator sizing is easier than the same in 700.4 & 701.4 i.e. the generator in hospitals is sized to demand load but in other buildings the generator is sized to connected load. Please correct me if i am wrong.

Thanks in advance

 

[dkidd]

You're right. It doesn't seem logical.

 

[RD35]

It is my understanding that 517.31 (D) addresses the reality that hospital emergency systems are usually very large and very diverse. If a designer were to follow only 700.4 and/or 701.4 when sizing equipment for a large hospital, he/she would be forced to specify equipment that is unreasonably large and expensive. I suppose the risk inherent in this approach on a large hospital is very low.

 

[m sleem]

I don't think they are mistaken since they intentionally indicate 400.4 & 401.4 in section 517.31(D), but what's the logic behind?

 

[m sleem]

It is my understanding that 517.31 (D) addresses the reality that hospital emergency systems are usually very large and very diverse. If a designer were to follow only 700.4 and/or 701.4 when sizing equipment for a large hospital, he/she would be forced to specify equipment that is unreasonably large and expensive. I suppose the risk inherent in this approach on a large hospital is very low.

May be!

 

[m sleem]

Any other feedback

 

[don_resqcapt19]

NFPA 99, Health Care Facilities Code, and not the NEC has purview over these requirements. You need to look to NFPA 99 for additional guidance.