Trivia:
What are the acceptable mounting elevations for a horn/strobe?
Hint: You won't find it in the NEC or the NFPA 72.
Hi Ryan, is this the answer? (ADAAG see note 6)
4.28.3* Visual Alarms. Visual alarm signal appliances shall be integrated into the building or facility alarm system. If single station audible alarms are provided then single station visual alarm signals shall be provided. Visual alarm signals shall have the following minimum photometric and location features:
(1) The lamp shall be a xenon strobe type or equivalent.
(2) The color shall be clear or nominal white (i.e., unfiltered or clear filtered white light).
(3) The maximum pulse duration shall be two-tenths of one second (0.2 sec) with a maximum duty cycle of 40 percent. The pulse duration is defined as the time interval between initial and final points of 10 percent of maximum signal.
(4) The intensity shall be a minimum of 75 candela.
(5) The flash rate shall be a minimum of 1 Hz and a maximum of 3 Hz.
(6) The appliance shall be placed 80 in (2030 mm) above the highest floor level within the space or 6 in (152 mm) below the ceiling, whichever is lower.
(7) In general, no place in any room or space required to have a visual signal appliance shall be more than 50 ft (15 m) from the signal (in the horizontal plane). In large rooms and spaces exceeding 100 ft (30 m) across, without obstructions 6 ft (2 m) above the finish floor, such as auditoriums, devices may be placed around the perimeter, spaced a maximum 100 ft (30 m) apart, in lieu of suspending appliances from the ceiling.
(8) No place in common corridors or hallways in which visual alarm signalling appliances are required shall be more than 50 ft (15 m) from the signal.
Roger:
Very good. That is the ADAAG requirement. Question: does your state recognize the ADAAG as the standard for new construction?...most states do not.
If they don't what standard do they use?
Ryan,
I very often quote the elevation stated in NFPA 72 for this question? Am I looking in the wrong book?
Ryan, the state doesn't enforce the adaag although many local municipalities do.
Our local code enforcement does for some parts.
Roger
Depending upon what document your jurisdiction uses for accessibility guidlines (ADAAG or ANSI A117.1), it will be what Roger stated or (assuming a wall mount) the ANSI standard of 80"-96" A.F.F., measured to the bottom of the device.
I believe that there are more states that enforce the ANSI than states that enforce the ADAAG.
I think you will find the same height requirement in NFPA 72 2002 edition para 7.5.4.
How about 14' to 17' high?
We do this a lot for ceiling mount horn/strobes in retail stores.
The normal spec around here is 84" to the top of the device.
Tough to achieve when you are doing the rough without the fire alarm system chosen so there are no cut sheets to give device dimensions.
Ron: Thanks for the input. I don't have a copy of the NFPA 72 because it is out of my jurisdiction, I leave it to the fire marhall. I call this out on plan review often and have been told by EE's that the 72 has a different elevation. Thanks for the correction.
Bob: I don't have the ANSI here at the house so I'll back this up on Monday, but I believe for a ceiling mount you are permitted to go up to the ceiling as long as it is not more than 30(?) feet A.F.F.
I agree that 30' is the max height on ceiling mounted strobes. Both ANSI 117.1 and NFPA 72 have a nice chart to establish coverage of a strobe considering the room size and strobe candela rating.
Help me out here, we are discussing a strobe that will reflect and bounce from many areas virtually being impossible to ignore or miss.
Now, we have maximum height requirements for an item that doesn't need to be directly looked at. (I always wondered why the word Fire was on the strobe, who could read it in an event)
Now I ask, we have an individual in a wheel chair that has limited mobility in their neck, do they need to see a flashing strobe or an EXIT SIGN?
Many times the exit signs (lights) are on the ceilings much higher than the strobes. (confused)
Roger
Roger, I wish I had a good answer for that :-p The only thing that I can think of is that accessibility requirements are for people with all sorts of disibilities, not just people in wheel chairs, but also people with hearing or sight impairments. The only thing that I can think of is that if someone were near blind they would need to see where the strange bouncing light was coming from, and this might not be an easy thing to do if the elevation were higher.
Again, I have no way to back that up, but it's the only thing I can think of.....?
OK, I'll buy that. So now every one reguardless of impairment knows there is a fire, how do we insure they can see the "exit signs" ?
I have heard (this is only hearsay on my part) of a building that had the exit signs mounted at door hardware level on the active side of the doors.
Roger
One of the ways that this is established is by placing exit signs at the floor level. Ever notice that in hotel/motel corridors there are signs at the ceiling and floor? The intent is that the corridor may be filled with smoke, requiring people to crawl to the exit.
My opinion is that this is kind of silly. If there is that much smoke in the building, you had beter have all of the occupants out already.
The building code has a concept called "travel distance" and "common path of egress travel". Basically, (depending on what kind of building), you are only allowed to travel 75 feet before you have the option to exit in more than one direction. Travel distance states that you can only go 300' (depending on the type of building) before arriving at an exit, such as a protected stair enclosure. Doing the math, you are expected to have all of your occupants to the exit in under 2 minutes! This includes the reaction time, the panic stage and the travel time. Pretty restrictive requirements when you think about it.
Sorry Roger I got off the topic there. In regards to exit lights, one of the things that was conirmed in the night club fire in Rhode Island was the belief that people exit in the same door that they enter. You could have had 5 exits from that club and there still would have been a panic to escape out of the front of the building. In many types of buildings, the "main entrance" is required to be signifigantly larger than the other doors. With that being said, perhaps the idea is that, if you can't see an exit sign, hopefully you can remember how you got to where you are and get back out.
The height requirement is to afford a minimum amount of light where the person is. If it is on a 50' ceiling, the light will not effectively make it to the floor for anyone to have it catch their eye.