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Thread: Exterior egress lighting

  1. #1
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    Exterior egress lighting

    I'm seeing two schools of thought from plans reviewers. Some want the exterior lamps supplied from and monitoring the interior lighting circuit(s), and accept single heads outdoors. Some want the exterior lamps supplied from and monitoring the exterior lighting circuit, and require two lamps per location. Between the IBC and NEC I see some basis for both views. I'd like to get any comments on what's acceptable other places, and hear any comments.

    Martin

  2. #2
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    Re: Exterior egress lighting

    Martin,
    In my area most want dual lamps. Weird thing is that they are ok with a two lamp fixture with one ballast. IMO that doesn't meet NEC.

    As for monitoring the interior or exterior lighting, I don't monitor the interior circuits to determine when to cut on the exteriors. Code requirement is that emergency fixtures be supplied from the circuit that supplies the normal lighting for the space. IMO interior lighting is not in the same space as the exterior lighting.
    "In this house, we obey the laws of thermodynamics" - H. Simpson.

  3. #3
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    Re: Exterior egress lighting

    NEC 701.11 (G) talks about unit equipment. It requires the unit equipment to be fed from same branch circuit that feeds the normal lighting in the area.

    This section requires that the outside lights, if using unit equipment for em power, be fed by the outside light circuit.

    Two lamps are required, so the failure of one of the lamps will not place the area in total darkness.

    (edited for poor spelling)

    Chris

    [ November 16, 2005, 01:05 PM: Message edited by: raider1 ]

  4. #4
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    Re: Exterior egress lighting

    Chris,
    Let me start by saying that I agree with your post. However to be a nit pick. Article 701 which which*you reference applies to legally required standby systems. Article 700 applies to emergency lighting so the unit equipment requirements in 700 should be used. Fortunately they are identical.

    Side bar, wonder why 700.12(F)3 says that unit equipment for emergency lighting must have provisions for one or more lamps when 700.16 requires two or more "lighting elements". Is there a difference between a lamp and a lighting element?

    Other Questions: Is a ballast a lighting element? If so doesn't that mean a two lamp compact flourescent fixture with a battery back and one ballast does not satisfy code requirements for emergency egress lighting?
    "In this house, we obey the laws of thermodynamics" - H. Simpson.

  5. #5
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    Re: Exterior egress lighting

    sceepe,

    You are right I opened the book up and didn't really see the article, my bad. :o

    Lucky they are basically the same.

    Good question about a "lighting element" I will be interested to see what others have to say.

    Chris

  6. #6
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    Re: Exterior egress lighting

    Thanks for the replies. What the NEC says is clear. The confusion seems to stem from the recent adoption of the IBC by many of the jurisdictions in the area, replacing the UBC. Arizona has home rule, so each governmental entity adopts whatever Code they want on whatever schedule they choose.

    Some people are apparently considering the exterior EM lighting as an extension of the interior, rather than being a stand-alone. The argument runs along the lines of scenarios where a tenant space loses power when the exterior lights are powered (possibly from a different source) but no turned on, so the exterior EM lighting does not come on, which means there's no exterior light on the egress path. There also seems to be divergence on the number lamp heads. Some treat each doorway as an area, but others apparently treat the outdoors as a single area.

    This will get better when the IBC is better understood, but at this point everyone is on a learning curve and the interpretations vary greatly.

    Martin

  7. #7
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    Re: Exterior egress lighting

    Many manufacturers including Lithonia, are providing inaccurate information about exterior emergency lighting. They often suggest that the exterior fixture be run from the inside exit light em power. This usually is a violation of 700 as pointed out above. I challenged Lithonia on this matter, and they didn't seem to understand that Article 700 applied.

    I believe that the exterior em lighting must sense the exterior lighting circuit, not the hallway circuit for example. You need the exterior em lighting when the exterior system fails, not necessarily when the hall lights go out. This usually requires a battery for the exterior fixture.

    Jim T

  8. #8
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    Re: Exterior egress lighting

    The more I think about this the less sure I am about it. Doesn't it make sense for the exterior fixtures to come one when the lighting circuit for the adjacent interior space trips/dies/fails.

    First we are only talking about a situation where the emergency fixtures are normally off. If the emergency fixtures are on photocell and burn all night, it doesn't make a difference what circuit they are connected to. There will be light outside the door no matter which circuits fail. However, if the exterior fixtures are normally off and come on only where the normal power is interrupted, wouldn't you want them to come on when the interior corridor lights fail.

    Take this scenario. Office building with exits on all 4 sides and a corridor leads to each door. The question is does code require the exterior fixtures to be wired to one outside lighting circuit (option 1) or each fixture wired to the circuits for the connecting interior corridors (option 2).

    In the option 1 scenario, If all exterior fixtures are on a dedicated exterior lighting circuit and its breaker trips, all batteries come on, all 4 fixtures burn. If interior corridor lighting circuit trips, the outside emerg lts do not come on.

    In the option 2 scenario, if interior corridor lighting circuit trips, corridor emerg lights and outside point of egress lts comes on. Isn't that a safer system which is what we want?

    700.12(F) says:
    The branch circuit feeding the unit equipment shall be the same branch circuit that is serving the normal lighting in the area and connected ahead of any local switches.
    Doesn't it make more sense to say the light outside the door is in the same area as the lights inside the door. As opposed to saying the light outside the door is in the same area as the lights on the other side of the building?

    Jim / raider what do you think?
    "In this house, we obey the laws of thermodynamics" - H. Simpson.

  9. #9
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    Re: Exterior egress lighting

    Sceepe,

    In senario 1, if the interior hallway circuit trips, the exterior will still be illuminated by the normal exterior lights. The unit equipment lighting only operates in an emergency, so there will be normal lighting for egress.

    In senario 2, if the interior hallway circuit also feeds the exterior unit equipment, than if the exterior lighting circuit tripped the exterior emergency lighting would not come on.

    IBC 1006.1 Illumination required. The means of egress. including the exit discharge, shall be illuminated at all times the building space served by the means of egress is occupied. This says that the exit discharge needs to be illuminated at all times.

    IBC 1023.6 Access to a public way. The exit discharge shall provide a direct and unobstructed access to a public way.

    It seems to be pretty clear that the exterior of the building needs the unit equipment to be fed from the same circuit as the required exterior egress lighting.

    Chris

  10. #10
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    Re: Exterior egress lighting

    Raider,
    Neither of the IBC sections you reference say anything about which circuit to connect the exterior emergency lighting to. I agree that you have to illuminate the exit at all times and I agree on the definition of an exit discharge. However, I don't think either of these code sections tell us how to wire an exterior emergency lights.

    As I said before, it may be a mute point. Most of the time the exterior fixtures are on a dedicated exterior circuit so that they can be switched with a photocell/time clock regardless of whether the code requires it.
    "In this house, we obey the laws of thermodynamics" - H. Simpson.

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