ECN Forum Forums Code Related Discussion NEC & other Code issues Horn/strobes

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.