ceiling-mount NAs and large stores.

I have frequently seen in my area in large stores when they replace the fire alarm system they go from having wall-mount NAs, on the walls and/or support beams to having NAs on the ceiling. Have you noticed this in your area?

the local Walmart did that, with wheelock MTs on the wall giving way to ceiling mountain spectralert classics

I’m thinking it may have something to do with part code part efficiency. Wider strobe coverage. Have they put remote strobe on the ceiling and put horns on the walls? That is one way they sometimes do it which is a waste. How they should do it is put the ceiling mount horn strobes on the ceiling and kill two birds with one stone.

I’m much better with sprinkler codes than alarms, but I do believe it has to do with increasing coverage. Strobes on the ceiling can alert a wider area than on walls, columns, etc.

That and wall mounted devices in a retail store tend to get blocked more easily by stock, signage, and displays. I probably write up more devices blocked in retail then I do devices that don’t work!

Same with the Walmart I work at; when it was first built it had wall-mount Wheelock MT-24-WM horn/strobes. When it was converted and expanded into a Walmart Supercenter, they put in a new Fire-Lite MS-9600UDLS system with SpectrAlert Advance horn/strobes. They put them EVERYWHERE, even in smaller offices and in the restrooms! I was told the Walmart corporation wanted it that way. And of course, another obvious difference was that the old alarms were on Continuous (a few co-workers told me that), while the new system is on Code-3.

My local Targets are like such. Red horns on the support beams and white RSS remote strobes on the ceiling.

An Alco I go to whenever I go to Nebraska did that. They had Simplex 2901-9833 horns on the walls, but they were replaced with Spectralert Advances on the ceiling.

Wall mount strobes generally have a wider coverage area than ceiling mount strobes, a strobes mounted high up on the ceiling quickly get de-rated and lose effectiveness. Usually when strobes are on the ceiling it’s for easier installation.

I am not expert at all, but it seems that in a retail setting, where you have aisles, displays, and not many walls (large open area stores like Walmart and Target tend to only have the four outer walls) it would seem that if you mounted strobes on the ceiling and had 110 cd, they would have better coverage than wall mounted ones. Newer Walmarts around here also mount them on conduite poles and lower them towards the ground.

If you have a wall mount strobe rated at 110cd, chances are the ceiling mount equivalent (same current draw) is only 95cd which will have less coverage area. Also by code NA’s can’t be mounted above 30 feet, and even then they are de-rated. For example, by code, a ceiling mount 75cd strobe at 20’ can cover a 44x44ft area, whereas at 30ft it can over cover a 30x30ft area. A wall mount 75cd strobe can cover a 45x45’ area. A wall mounted strobe should be mounted at 80" or within 6" of the ceiling (if the ceiling height is under 80"). This is all in chapter 18 of the nfpa 72.



In aisles, wall mount on columns will do better, in more open areas you might opt for ceiling mounts purely for installation costs or because of a lack of columns.

My Walmart did the same thing. There are still two wheelock MTs hanging on the wall in the Walmart. They have a mix of SpectrAlert classic horns and horn/strobes on the ceiling.