NEC 517.26

[Kidd]

Hi all,

Designing a backup system for a small clinic. I've got a type 2 EES with the only life safety equipment being egress lighting and some task lighting. I've got an equipment branch as well.

Going through article 517 it gives guidance on the backup run time requirements for the life safety branch (article 517.26) stating to follow article 700. So I assume 90 minute backup for the life safety branch but what about the equipment branch? Planning on using battery backups for the egress/task lights, and a generator for the equipment branch but I don't see a section that states run time requirements for the equipment branch or that points back to any of the 700, 701 or 702 articles? I looked through a few other NFPA codes, and found most point back to NEC 517. Have you all ever come across this or designed something similar?

Thanks!

 

[roger]

The equipment branch is the equivalent of 702 and doesn't have very strict requirements.
The Equipment branch can be shed if necessary whereas the Critical and Life Safety branches are crash and burn.

 

[jim dungar]

Life safety needs to to be backed up for as long as it needs to be run. I would think 90 minutes for egress lighting would be sufficient. The equipment branch needs to be backed up for as long as the client wants it.

 

[Kidd]

Got it, thanks guys!

On the same note, I was under the impression that the critical branch should also have the same 90 minute run time requirement. Going back and looking at the code, it doesn't have a statement about following article 700 the same way the life safety branch does. The only thing I see is the requirement for having it turn on within 10 seconds [NEC 517.32(B)], but no mention of runtime. I always assumed it was the 90 minute minimum, but am I wrong in that assumption?

 

[Strathead]

Got it, thanks guys!

On the same note, I was under the impression that the critical branch should also have the same 90 minute run time requirement. Going back and looking at the code, it doesn't have a statement about following article 700 the same way the life safety branch does. The only thing I see is the requirement for having it turn on within 10 seconds [NEC 517.32(B)], but no mention of runtime. I always assumed it was the 90 minute minimum, but am I wrong in that assumption?

I think you are looking in the wrong codes. NFPA 99 would be where I would start. NFPA 101 may have something in it, and NFPA 110 would be another reference. There are also design standards for various healthcare types as well. The information in the NEC is less about the design of the system and more about the installation.

 

[Strathead]

Got it, thanks guys!

On the same note, I was under the impression that the critical branch should also have the same 90 minute run time requirement. Going back and looking at the code, it doesn't have a statement about following article 700 the same way the life safety branch does. The only thing I see is the requirement for having it turn on within 10 seconds [NEC 517.32(B)], but no mention of runtime. I always assumed it was the 90 minute minimum, but am I wrong in that assumption?

In a hospital, for example, life safety isn't merely to allow time to evacuate. That is what the 90 minutes is for. In a hospital, you will have people refuge in place, so the time will be much longer in most cases. I think the stand alone emergency department we just did had a calculated run time of 30 hours. A stand alone ED is actually classified by code as a hospital.

 

[Kidd]

I think you are looking in the wrong codes. NFPA 99 would be where I would start. NFPA 101 may have something in it, and NFPA 110 would be another reference. There are also design standards for various healthcare types as well. The information in the NEC is less about the design of the system and more about the installation.

Thanks for the reply! Yea I checked out NFPA 99. Article 6.7.6.2.1.5 points back to NEC Article 700. NFPA 101 points to NFPA 99, but I know you're right about the run time being longer in certain health care facilities. I forget the exact wording, but basically calculate a run time long enough to keep life supporting equipment running or long enough to finish any surgeries/operations. I'm sure there's more reasons to calculate a longer run time, I just wasn't sure what (or if) there are standard minimum run times for critical or equipment branches.

I appreciate everyone's response, thanks!

 

[JARSuites]

Not from Texas but it looks like Texas has the 2015 IBC adopted. Chapter 27 Section 2702.1.4 Load Durations. Minimum 2 hour duration unless otherwise specified in another chapter.

Edit: If the healthcare facility is a licensed facility or CMS certified the minimum duration would be dependent on there rules. Each facility(hospital, nursing home, ambulatory surgery centers) will have different duration that they are required to have.