Stairwell Egress Lighting

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Hello all,

See code section below. Both 2005 & 2008 NEC say the same thing. My interpretation is that (2) emergency branch circuits or equivalent should be designed into a required egress path such as an exit enclosure/stairwell. If (1) branch circuit was used for the whole stairwell and a ground fault occurred, the circuit breaker would trip rendering the stairwell in total darkness or at least dark enough to create a hazard when attempting to egress. Of course (2) sources of power should be available (Normal & Generator usually). I think the intent of this section actually adds another level of redundancy so that if the (1) panel or branch circuit fails, another will still be energized.

Need Comments.
Thanks .... Jeff


700.16 Emergency Illumination


Emergency illuminationshall include all required means of egress lighting, illuminatedexit signs, and all other lights specified as necessaryto provide required illumination.Emergency lighting systems shall be designed and installedso that the failure of any individual lighting element,such as the burning out of a lamp, cannot leave in totaldarkness any space that requires emergency illumination.Where high-intensity discharge lighting such as highandlow-pressure sodium, mercury vapor, and metal halideis used as the sole source of normal illumination, the emergencylighting system shall be required to operate untilnormal illumination has been restored.Exception: Alternative means that ensure emergency lighting
illumination level is maintained shall be permitted.

 
Stairwell Egress Lighting

Ok I understand that it doesn't require (2) circuits but it requires design and installation such that any individual lighting element can't render the path in total darkness. So if you had a stairwell that covered (5) stories and everything was on the same circuit and perhaps other stairwell circuits came off the same panel and that panel tripped, all the stairwells would be dark. I'm just thinking that this section wants a better design where (1) source doesn't feed all the stairwells or (1) circuit doesn't feed multiple stories. It does lead one to believe that it's all about how many lights and obviously we don't want it all wired in series. I appreciate the comments and no I did not write this up on my Project.
 

anbm

Senior Member
Ok I understand that it doesn't require (2) circuits but it requires design and installation such that any individual lighting element can't render the path in total darkness. So if you had a stairwell that covered (5) stories and everything was on the same circuit and perhaps other stairwell circuits came off the same panel and that panel tripped, all the stairwells would be dark. I'm just thinking that this section wants a better design where (1) source doesn't feed all the stairwells or (1) circuit doesn't feed multiple stories. It does lead one to believe that it's all about how many lights and obviously we don't want it all wired in series. I appreciate the comments and no I did not write this up on my Project.


Reading building code...couldnt remember which section now, but I think we must to use (2) circuits serving egress lights in starwell. One circuit can be used if the lights have integral battery.
 

copper chopper

Senior Member
Location
wisconsin
anbm you are correct, for say a 5 story stairwell you could put all lights on the same circiut providing they have a battery back up or a seperate lamp to illuminate the stairwell for up to 2 hours ( if its not a place of assembly then it would be 8 hours).OR if this complex has a generator then you could have the whole stairwell on the generator panel or say a 3 lamp flourescent fixure were 2 lamps are on normal power and 1 lamps on the generator power.And if this stairwell leads to egress it needs an exterior light as well with these same reqirements.These are in the lighting codes of the building code section.
 

Ragin Cajun

Senior Member
Location
Upstate S.C.
Reading building code...couldnt remember which section now, but I think we must to use (2) circuits serving egress lights in starwell. One circuit can be used if the lights have integral battery.

Can anybody tell us exactly where this is found? I looked in the IBC and either it's not there or I missed, it.

Thanks,

RC
 

steve66

Senior Member
Location
Illinois
Occupation
Engineer
Reading building code...couldnt remember which section now, but I think we must to use (2) circuits serving egress lights in starwell. One circuit can be used if the lights have integral battery.

Well, if you aren't doing internal batteries, that means you have some remote generator or emergency supply. So that would be one circuit required for the emergency egress lights.

Normally, a space would also have non-emergency lights (normal lights on a normal branch circuit.) So that would be the second circuit.

I would not design a stairwell placing all the lights on the emergency circuit. The normal circuit is a backup for the emergency circuit. If a branch breaker on the emergency circuit tripped (picture the load side of the ATS), it would leave the stairwell in total darkness (even when utility power is still available).

In article 700 of the NEC, it says that emergency power shall be provided by a separate system. So in my opinion, its that section that basically requires two circuits - one normal and one emergency (unless there are individual batteries.)

Edit: Look at 700.17 (1) and (2) in the NEC.
 
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anbm

Senior Member
Well, if you aren't doing internal batteries, that means you have some remote generator or emergency supply. So that would be one circuit required for the emergency egress lights.

Normally, a space would also have non-emergency lights (normal lights on a normal branch circuit.) So that would be the second circuit.

I would not design a stairwell placing all the lights on the emergency circuit. The normal circuit is a backup for the emergency circuit. If a branch breaker on the emergency circuit tripped (picture the load side of the ATS), it would leave the stairwell in total darkness (even when utility power is still available).

In article 700 of the NEC, it says that emergency power shall be provided by a separate system. So in my opinion, its that section that basically requires two circuits - one normal and one emergency (unless there are individual batteries.)

Edit: Look at 700.17 (1) and (2) in the NEC.


In my mind, I think you can have all stairwell lights on emergency power, but you have to alternate them so the lights can be fed from (2) separate circuits in case one breaker trips, there are still egress lights powered from other circuit. See NFPA-101 7.9.2.3(2) below.


7.9.2.3* The emergency lighting system shall be arranged to provide the required illumination automatically in the event of any interruption of normal lighting due to any of the following:
(1) Failure of a public utility or other outside electrical power supply
(2) Opening of a circuit breaker or fuse
(3) Manual act(s), including accidental opening of a switch controlling normal lighting facilities.

 

steve66

Senior Member
Location
Illinois
Occupation
Engineer
In my mind, I think you can have all stairwell lights on emergency power, but you have to alternate them so the lights can be fed from (2) separate circuits in case one breaker trips, there are still egress lights powered from other circuit. See NFPA-101 7.9.2.3(2) below.


7.9.2.3* The emergency lighting system shall be arranged to provide the required illumination automatically in the event of any interruption of normal lighting due to any of the following:
(1) Failure of a public utility or other outside electrical power supply
(2) Opening of a circuit breaker or fuse
(3) Manual act(s), including accidental opening of a switch controlling normal lighting facilities.


You could put them all on 2 separate emergency circuits. But then you have to claim that all the lights are legally required egress lights since those are the only loads allowed on the emergency transfer switch.

Also, if there is a shared main circuit breaker on the load side of the transfer swtich, then you aren't complying with #2 above. (Picture both branch circuits coming from the same panelboard that has a main circuit breaker. If that breaker trips, the area is in the dark.) I could even see an issue if both branch circuits are fed from the same transfer switch. Transfer switches do sometimes go bad.

Much better to have one normal circuit & one emergency ckt, or two emergency circuits from separate transfer switches.
 

iwire

Moderator
Staff member
Location
Massachusetts
For what it is worth, in buildings with generators I have never seen a 'normal' circuit used in an egress stair.

Typically the only lights in the stair are on an emergency circuit as there are so few lights all of them are required.

I also usally see only one circuit used. You can call it poor design but IMO it is code compliant.
 
Stairwell Egress Lighting

For what it is worth, in buildings with generators I have never seen a 'normal' circuit used in an egress stair.

Typically the only lights in the stair are on an emergency circuit as there are so few lights all of them are required.

I also usally see only one circuit used. You can call it poor design but IMO it is code compliant.

IWIRE - I understand what you're saying but consider this ... 700.16 says the system shall be "designed" so that any individual lighting element failing won't render the stairwell dark. When they say "such as" it gives an example of what could cause and outage but there are other situations that could also render the stairwell dark. If the individual lighting element somehow caused a ground fault, then the breaker would trip. This would violate 700.16. It's true that mostly every stairwell is wired with one emergency branch circuit. I just happened to stumble on this because a breaker did trip on my Project and the stairs went dark. I looked into it and saw this section of code. I would have never questioned it otherwise.
 

anbm

Senior Member
You could put them all on 2 separate emergency circuits. But then you have to claim that all the lights are legally required egress lights since those are the only loads allowed on the emergency transfer switch.

Also, if there is a shared main circuit breaker on the load side of the transfer swtich, then you aren't complying with #2 above. (Picture both branch circuits coming from the same panelboard that has a main circuit breaker. If that breaker trips, the area is in the dark.) I could even see an issue if both branch circuits are fed from the same transfer switch. Transfer switches do sometimes go bad.

Much better to have one normal circuit & one emergency ckt, or two emergency circuits from separate transfer switches.

I would say the intent of code is for branch circuiting, otherwsie, what happen if generator doesn't start or generator main breaker fails, etc, you can list all other scenerios.
 

steve66

Senior Member
Location
Illinois
Occupation
Engineer
For what it is worth, in buildings with generators I have never seen a 'normal' circuit used in an egress stair.

Typically the only lights in the stair are on an emergency circuit as there are so few lights all of them are required.

I also usally see only one circuit used. You can call it poor design but IMO it is code compliant.

Bob: That may be common, but I don't believe that complies with 700.17.

I would say the intent of code is for branch circuiting, otherwsie, what happen if generator doesn't start or generator main breaker fails, etc, you can list all other scenerios.

I don't believe that's a correct interpertation. The other items you mention would only be an issue during the times the utility power is out. A main breaker on a emergency panelboard could trip leaving a stairwell in darkness even when utility power is available. The normal power is a backup for the em power except only the short times the utility power is out.

IWIRE - I understand what you're saying but consider this ... 700.16 says the system shall be "designed" so that any individual lighting element failing won't render the stairwell dark. When they say "such as" it gives an example of what could cause and outage but there are other situations that could also render the stairwell dark. If the individual lighting element somehow caused a ground fault, then the breaker would trip. This would violate 700.16. It's true that mostly every stairwell is wired with one emergency branch circuit. I just happened to stumble on this because a breaker did trip on my Project and the stairs went dark. I looked into it and saw this section of code. I would have never questioned it otherwise.

I believe you have the right idea, but I think a "lighting element" only includes a lamp or a bulb. Not a breaker. I think 700.17 is the relavant section.

By the way, did the breaker trip while the utility power was still available??
 
Bob: That may be common, but I don't believe that complies with 700.17.



I don't believe that's a correct interpertation. The other items you mention would only be an issue during the times the utility power is out. A main breaker on a emergency panelboard could trip leaving a stairwell in darkness even when utility power is available. The normal power is a backup for the em power except only the short times the utility power is out.



I believe you have the right idea, but I think a "lighting element" only includes a lamp or a bulb. Not a breaker. I think 700.17 is the relavant section.

By the way, did the breaker trip while the utility power was still available??

The circuit breaker poped when electricians opened the old panel and a wire arced against the panel. This panel had circuits for (2) stairwells so they went dark. The power source has nothing to do with this debate. All 700.17 and other sections related tell you is that you have to have normal power and back-up power. That's not the issue. The issue is when a lighting element causes a fault that will renders the stairwell dark. In the scenario I mentioned, the breaker tripped by some other action, but it made me look at this section. If one of the fixtures were to cause a fault, it could trip the breaker. I know ballasts are made to prevent this, so the chance of this happening may be minimal but we do other things to protect against fires, earthquakes etc... The chance of a fire or earthquake is minimal too. There's that old saying sh_t happens. At this point, I don't think this is enforceable, but it's something to think about.
 

anbm

Senior Member
The circuit breaker poped when electricians opened the old panel and a wire arced against the panel. This panel had circuits for (2) stairwells so they went dark. The power source has nothing to do with this debate. All 700.17 and other sections related tell you is that you have to have normal power and back-up power. That's not the issue. The issue is when a lighting element causes a fault that will renders the stairwell dark. In the scenario I mentioned, the breaker tripped by some other action, but it made me look at this section. If one of the fixtures were to cause a fault, it could trip the breaker. I know ballasts are made to prevent this, so the chance of this happening may be minimal but we do other things to protect against fires, earthquakes etc... The chance of a fire or earthquake is minimal too. There's that old saying sh_t happens. At this point, I don't think this is enforceable, but it's something to think about.

I think the best design is connect every stair landing light to same emergency corridor/egress lights serving that floor and don't share emergency lighting circuits between floors,
this can prevent the whole stair lighting goes into dark as you said. There are not that many lights in stairwell, it does not hurt to have them all
on emergency power.
 
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