Exterior egress lighting

Status
Not open for further replies.
hmspe

hmspe

Senior Member
Location
Temple, TX
Occupation
PE
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
 
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.
 
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 ]
 
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?
 
Re: Exterior egress lighting

sceepe,

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

Lucky they are basically the same.

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

Chris
 
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
 
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
 
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.
Click to expand...
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?
 
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
 
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.
 
Re: Exterior egress lighting

Been out of town, sorry I missed the continuation of this topic. I agree completely with Raider1.

Sceepe, how will you provide exterior illumination if the exterior circuit fails, unless the exterior em pack senses the condition of the exterior circuit? Raider1 is correct that 1006.1 requires exterior illumination at all times the building is occupied. I don't see how this can be accomplished with the scenario you described at the end.

I've noticed the real problem is teaching contractors to pull a hot wire with the switched leg(s) to the exterior unit.

Jim T
 
Re: Exterior egress lighting

Raider1 is correct that 1006.1 requires exterior illumination at all times the building is occupied. I don't see how this can be accomplished with the scenario you described at the end.
Click to expand...
Because you have to illuminate the exterior egress at all times, if you want to use a wall pack (or a remote head from an interior emerg wall pack) you need a second fixture that runs on "non emergency power". This non emerg fixture will burn anytime the building is occupied (except for the photocell exception). Now I agree that the remote head and the non-emerg fixture have to be on the same circuit. When "normal" power is lost to the non emerg fixture, the wall pack or remote head will run off the battery. So the exterior egress is illuminated all the time. This is the same as having one flourescent fixture with an internal battery pack.

Now the issue is whether the non emerg fixture and the wall pack need to be on the interior lighting circuit or the exterior lighting circuit. My contention is that the interior circuit is better because the space on either side of the exit door will be on battery power at the same time.

Sceepe, how will you provide exterior illumination if the exterior circuit fails, unless the exterior em pack senses the condition of the exterior circuit?
Click to expand...
In this situation, the non emerg fixture will stay on because it is powered from the interior circuit which has not failed.

I've noticed the real problem is teaching contractors to pull a hot wire with the switched leg(s) to the exterior unit.
Click to expand...
I could not agree more. Nothing worse than telling a guy on final inspection that he has to go back a repull an unswitched hot to all of his exterior fixtures with battery packs. I have had it happen and the guy looked like I kicked him in the teeth. I have put "warnings" all over my lighting plans and details.
 
Re: Exterior egress lighting

So maybe the solution would be unit equipment that can sense two circuits....

Or, maybe it shouldn't make a difference. One possibility would be invocation of the "three circuit" rule, since most projects have multiple outdoor lighting circuits. This would get back to the definition of "space" -- is the applicable area just around the door, or the "path to a public way", or the side of the building, or the entire lot? If there are three or more outdoor circuits then it might be fully acceptable to use the interior circuit to supply the exterior EM lighting. The 1999 NEC is what's handy at the moment, and 700.12(e) Exception does not preclude the separate circuit for EM from supplying other loads (if the exception said "dedicated" it would be a different matter). The entire lot outdoors could easily be considered "a separate and uninterrupted area".

My opinion is that the safest configuration is to have the interior EM pack supply the lighting for the exterior egress path, since the critical emergency situation is a failure of the normal interior lights. Having the exterior lights fail may be a Code violation and an inconvenience, but it's generally not an emergency situation requiring egress if the outside lighting is the only thing that's failed. Between street lights, moonlight, and etc., it's seldom totally dark outside, anyway. In this case what I consider safest may not be what is required to meet Code.

I think this is an area that needs correlation and clarification in the Codes.

Martin
 
Re: Exterior egress lighting

sceepe

Thanks for the clarification, now I can see what you are saying, and I agree that it would work.

The only other problem, and it won't always be one, is that Chapter 13 of the IBC adopts the IECC. 805.2.3 of the IECC says the exterior lighting must be automatically switched or on 24 hours a day. If you wall switch the hall lights, you shouldn't wall switch the exterior fixture.

Jim T
 
Re: Exterior egress lighting

Sceepe,

I also agree that it could work. You would need to make sure that the exterior em light meets the requirements of 700.16.

Chris
 
Status
Not open for further replies.
Top