517.31(B)

[m sleem]

I am in a situation where there is existing design for hospital need to be rectified in order to meet NEC requirements, the whole essential branch is currently supplied by common BusDuct system through one ATS without segregation between emergency branches as required in code,

In order to rectify the design without replacing the BusDuct system, can we keep the BusDuct system supplied by normal supply only (ATS to be removed) and for each #3 floors there will be tap off point (plug in) supplies one ATS feeding the three branches (life safety, critical, equipment) as long as it has 150 kva or less?

 

[m sleem]

Any feedback ?

 

[david]

I am in a situation where there is existing design for hospital need to be rectified in order to meet NEC requirements, the whole essential branch is currently supplied by common BusDuct system through one ATS without segregation between emergency branches as required in code,

In order to rectify the design without replacing the BusDuct system, can we keep the BusDuct system supplied by normal supply only (ATS to be removed) and for each #3 floors there will be tap off point (plug in) supplies one ATS feeding the three branches (life safety, critical, equipment) as long as it has 150 kva or less?

IMO, No

 

[m sleem]

IMO, No

Would you cite a reference for objection

 

[steve66]

The 150 KVA limit is for an entire facility, not just for each ATS.

So I also agree - not allowed.

 

[m sleem]

Would you cite a reference for objection

It's confusing, how a hospital has less than 150 kva emergency loads?,

 

[kwired]

It's confusing, how a hospital has less than 150 kva emergency loads?,

Small hospital?

Don't remember size of generator at a small town hospital I used to do work at was, but only had a 200A 208/120 feeder supplied by it, so likely 75kVA or less.

 

[steve66]

It's confusing, how a hospital has less than 150 kva emergency loads?,

It could also be a small surgery center, or other healthcare facility where critical care is provided.

 

[m sleem]