Emergency Load - Sharing generator - Code Questions

[anbm]

I have this situation if anyone has experienced about it, please help, thanks:

We have a hospital which has its own utility xfmrs and (4) emergency generators as backup emergency source.

There is a medical office building (MOB) located next to the hospital which also has its own utility xfmr. However, we want to have some emergency load (lighting and elevator, receptacles) to be fed from same generator sources as hospital by adding a separate ATS.

Will code allow MOB emergency load be fed from same emergency sources at hospital? The reason owner doesn't want to have a separate generator for office bulidng because of the space, mantenance amd its emergency load is not large enough.

TX-man

 

[dpc]

See NEC 517.30. I believe this would be allowable within NEC requirements provided all other conditions are met, including automatic load shedding and selective coordination. The MOB would have to realize that if there was any type of overload, fault, voltage dip, etc, they would be automatically tripped off the local generator in an instant.

Whether or not doing it this way is a good idea would be a different question.

 

[anbm]

Thanks, DPC. What's your occupation field? May I ask?

Anbm

 

[dpc]

I'm a consultant - but I don't specialize in health care facilities, so you may want to get a second opinion.

 

[davidbeach]

For what it's worth, when I was doing health care I would have had no problem with the concept of feeding the MOB from the central generator. The specific details do matter considerably though.

 

[RyanJackson]

Be rather careful when you call an elevator an "emergency" load. If you are governed by the IBC, Chapter 27 will call it a standby load, unless your building is greater than 4 stories...

 

[davidbeach]

Strictly speaking there is no "emergency" power in a health care facility; just Life Safety, Critical, Equipment (in various flavors), and potentially optional standby.

 

[RyanJackson]

David: I agree... sort of. When you look at 517.26, it requires compliance with 517.26. While you are correct, these systems must still compl;y with ARticle 700.

Interestingly, there was an accepted proposal in the 2008 cycle to delete this section, and it nearly passed the comment stage. Luckily it was finally rejected.