Sometimes code gets in the way. E.g. in the school I went to growing up they had to have firealarms in all kind of closets and storage rooms. We got at least once per semester a firealarm when some teacher went in to sort stuff due to the dust.

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js2 5 hours ago | parent [-]

There's generally two types of smoke alarms each with pros/cons: photoelectrical which are very susceptible to dust and ionizing which generally are not:

https://www.nfpa.org/news-blogs-and-articles/blogs/2023/03/0...

I wouldn't think code dictated the alarm type. (I just replaced all nine sensors in my home due to age and went with all photoelectric this time and it was less than six months before I had my first false alarm. Never had any false alarms with previous ionizing type.)

	▲	femto113 4 hours ago \| parent \| next [-]
		"False" isn't really binary. In my condo building we used to have in-unit smoke detectors wired directly into the building alarm, which meant whenever anyone in any of 200 units burned their toast sirens were blaring. The smoke was real, it just wasn't a threat to the whole building. This would happen once a month or so, and because it's a highrise that sent the big ladder truck down our little street. The fire department got sick of this so we updated a few years ago to have heat detectors that are wired into the building-wide alarm but the smoke detectors only go off locally. False alarms have fallen to basically zero, but the downside is that for reasons not entirely clear to me the new system has to get inspected every 6 months, which includes making sure every one of 200 heat sensors is working, so we get days with 100s of very short bursts of the alarms twice a year.
	▲	Animats 3 hours ago \| parent \| prev [-]
		In my aerospace days, our buildings had both ionization and temperature detectors, plus water flow on the sprinklers. Any detection would sound loud buzzers locally, but two sensors, or water flow, had to trigger before everything powered off. That's common in big installations. We once got an alarm because the heating element in a computer room air conditioner had turned on for the first time ever. It was defective and started to smoke. Smoke detection tripped, buzzers sounded, lights on a panel showed where the problem was, and alarms went off in the security control center. But this didn't trigger building evacuation or full power down. That took confirmation from a second sensor. Someone ran into that computer room, saw smoke coming from the A/C unit, and pulled the big red power switch, installed by the safety people, on the air conditioner. Then we had time to shut down normally, the safety people came to clear the alarm, and the HVAC people came to fix the problem. I kept the burnt heating element on my desk for a few days for people to see. This is typical for big industrial plants. Bad stuff will happen, and you have procedures for it.