NEC Article 700: Emergency Lighting

[gh0st]

Hello, I'd appreciate getting your interpretation on the following NEC 2017 Code sections.

700.15: Does entire area fed with a single emergency lighting circuit comply? Clearly not every fixture in the space would be needed to meet the minimum FC levels. Seems to be a common installation in corridors, stairwells, core & shell designs for future tenant spaces.

700.16: How should "any individual lighting element" be considered and how do we typically demonstrate compliance? Is this a component within the luminaire OR an element up to the luminaire, such as a branch circuit or breaker, or even the generator? Emergency lighting is typically single fixture (if not required by other, say hospital, applications) supplied via single (generator/inverter) emergency branch circuit, controlled via UL 924. There is no redundancy in these installs.

700.17(1): Do central lighting inverters comply such as https://www.myerseps.com/wp-content/uploads/2018/07/Illuminator-IE-Cut-Sheet.pdf ? This only carries a UL 924 listing and provides only bypass and no "transfer". Is a UL 1008 listing required? However, under normal conditions the inverter is fed via 'normal/utility' power and during loss of normal power, will be "transferred" to the battery back up.

700.17(2): Does an entire 4 story stairwell fed via (1) emergency circuit to LED fixtures with integral occupancy sensors (CA req.) that provide for step dimming to 50% during unoccupied conditions comply? If the branch circuit from the inverter to the load fails, the entire stairwell will be in total darkness. However, upstream to that there are technically (2) sources: Normal: Utility & Emergency: Battery/Generator back up. Since new stairwells are required to be provided with 10 FC, even during a "vacancy" condition minimum lighting levels would technically be maintained. I have also seen similar applications in parking garages.

700.19: Appears dedicated neutrals are required.

700.24: I have not come across any luminaires/light fixtures that are "listed for use in emergency systems". How do we comply if we want to avoid the use of Unit Equipment?

700.25: If the example I noted in 700.17(2) is not compliant, it seem a listed branch circuit device is required. I'm only aware of this one: https://www.etcconnect.com/Products...ing-Systems/Branch-Circuit-ELTS/Features.aspx. It would not appear that the Bodine GTD is is compliant with this section. Side note: the GTD is only UL 924 listed, even though GTD stood for Generator Transfer Device.

TIA

 

[steve66]

That's a lot for one post, but I'm give my opinion for the first two:

700.15: Not allowed unless every fixture is required for emergency egress. You say its common, but I don't think I have ever seen this except in spaces with only one fixture.

700.16 - I take "lighting element" to mean the lamp or bulb or LED. Something that is part of the fixture. I also think this originally meant something that would need replaced on a regular basis (aka - a lamp), but now we have LED and those basically last forever. LED's also have multiple LED elements. But there are some fixtures available with dual driver and dual LED boards for AHJ's that require that for redundancy. I do NOT think this includes the branch breakers or generator, which are covered by other codes and requirements.

 

[gh0st]

That's a lot for one post, but I'm give my opinion for the first two:

700.15: Not allowed unless every fixture is required for emergency egress. You say its common, but I don't think I have ever seen this except in spaces with only one fixture.

700.16 - I take "lighting element" to mean the lamp or bulb or LED. Something that is part of the fixture. I also think this originally meant something that would need replaced on a regular basis (aka - a lamp), but now we have LED and those basically last forever. LED's also have multiple LED elements. But there are some fixtures available with dual driver and dual LED boards for AHJ's that require that for redundancy. I do NOT think this includes the branch breakers or generator, which are covered by other codes and requirements.

Thanks for your reply.

Regarding 700.15, I see many designs where a single emergency circuit (from a panel backed by generator or central inverter) is the only source of power to an entire stairwell. This makes sense for me since lighting is typically (1) fixture per landing and sacrificing any 1 would likely not meet minimum FC requirements.

In corridors and future TI spaces, this is where I struggle. Clearly, there's a savings with not having to bring another circuit and the code doesn't indicate maximum light levels. However, if the goal is to limit the unnecessary loads (due to 1FC avg obtained with just select fixtures) then I'd agree.

Good to hear we are in agreement on 700.16.

If you able to provide your thoughts on the other items, it would be much appreciated!