517 - Health Care Facilities - Nursing Home < 150KVA

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HHP

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An existing nursing home facility would like to install a new generator. Currently there is no backup power source and all the power to the building is fed from 2 sub-panels which both feed critical and non critical loads.

My question is:

Is it permitted to backup the entire building with a generator and use one transfer switch and feed the existing panels as they are?

OR

Is it a requirement to separate critical branch and life safety branches and feed them from one transfer switch and install another transfer switch to feed non-essential loads.
 
First, I would start with the State's Health Care licensing group to see if they have any requirement for Nursing Homes that would exceed the NEC.

Next look at 517.40. It lays out the requirements for transfer switches. The switch serving the essential electrical system must be separated should not serve other loads.
 
517.41(B) would allow a single transfer switch for a facility with an ESS load under 150 KVA. But you would need to meet the exceptions under 517.40(A) first.
 
Double Post**

However, if the nursing home is not providing any life support equipment they may be able to get out of that requirement based on 517.40(B)

The separation requirement is in 517.30(B)(3).
 
Thank you for your responses.

My original question was "am I able to backup the entire building with one ATS and feed both critical and non critical loads with one transfer switch." I believe if I meet the exceptions of 517.40(a) this would be OK.

If not then by code, as I understand it, it would require separation of both critical and non critical, with each type of load fed from a separate transfer switch.

Thanks again!
 
HHP said:
Yes. Actually the entire building load is under 150kva according to utility max demand data. It is a small facility.
Click to expand...

Sorry, now I see that was in your title.

I agree with what you said in your last post.

I'm not sure what your optional loads are, but if the facility considers them necessary, you might be able to classify them as critical per 517.43(B)(3).

As a side note, I'm not sure how anyone handles the "delayed automatic" connection (517.43(B)) when they have a single transfer switch. The delay is usually programmed into the transfer switch, and its usually limited to the 10 sec. outage time anyway. With a single transfer switch, you obviously can't have one connection delayed after another without adding additional contactors and such. At that point it probably makes sense to just use a second transfer switch.

My guess is that most people ignore the "delayed" part since most modern generators can usually handle a 100% step load. (Larger motors are probably the exception, since those could overload the generator, and the delay can usually be added in the controls.)
 
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