NEC Life Safety Branch 517.32 (e)

[jampe]

For a life safety branch circuit for a hospital, I am interpreting this section of the code to allow, or require, night lighting in the generator room and transfer switch rooms with battery backup fixtures to be supplied from the LS circuit. Does "task illumination" in generator or transfer switch rooms require all fixtures to be on LS circuit? I don't think so, but others appear to think so. Request thoughts on interpretation of "Task illumination battery charger for battery powered lighting units".

 

[david]

I think it would depend on how many sources of lighting you have in these rooms. Do these rooms have a normal lighting circuit as well as a emergency lighting circuit? Are the wall packs (unit equipment ) working to back up the emergency lighting in these rooms?

If so only the emergency lighting source would be allowed to be supplied from the life safety branch.

It sounds like your rooms have a lighting circuit with unit equipment providing the emergency lighting in these rooms.
If so then the battery charging system for the unit equipment must be supplied by the life safety branch
Couple that with 700.12(f) the loss of the lighting circuit in those rooms would have to trigger the unit equipment to provide emergency lighting. I would say that the lighting circuits associated with the unit equipment must be supplied by the life safety branch.

 

[steve66]

For a life safety branch circuit for a hospital, I am interpreting this section of the code to allow, or require, night lighting in the generator room and transfer switch rooms with battery backup fixtures to be supplied from the LS circuit. Does "task illumination" in generator or transfer switch rooms require all fixtures to be on LS circuit? I don't think so, but others appear to think so. Request thoughts on interpretation of "Task illumination battery charger for battery powered lighting units".

No, you are not required to have all the lights in the generator or transfer switch room on the LS branch. You should have the battery powered light in the generator or ATS room on the life safety branch.

I believe you could put a few other lights in these areas on the life safety branch, but the critical branch is probably better per 517.33(9).

In my opinion, it would be a bad design to put all the lights in these areas on the LS branch. I suggest putting them on at least two branches - for example, critical and normal.

ATS's sometimes fail, and circuit breakers sometimes trip, even when the utility power is available. If the right component fails, the critical branches will be without power while the normal power is still availble. No sense in having to try and find a problem like that in the dark.

 

[david]

In my opinion, it would be a bad design to put all the lights in these areas on the LS branch. I suggest putting them on at least two branches - for example, critical and normal.

ATS's sometimes fail, and circuit breakers sometimes trip, even when the utility power is available. If the right component fails, the critical branches will be without power while the normal power is still availble. No sense in having to try and find a problem like that in the dark.

you state at least two branches and I agree that would be better, then you go on to say for example the critical branch and the normal branch. You did not state the Life safety branch and critical branch or the life safety branch and the normal branch.

I agree it would be a better design to have these areas served by at least two of these three choices.

After rereading the op post these emergency lighting fixtures have battery units as part of the fixture not using wall packs in these rooms, so I would include the life safety branch and normal branch as the two branch choices in these areas.