Not quite, they simply protect pull stations from damage and discourage false alarms. Some of them do have a small horn in them, but they do not activate the system nor are they activated by the system.
NAs (notification appliance) are the horns and strobes wired into the fire alarm system.
I had a basketball hit one Truealerts in the gym at the summer camp I was volunteering at, it set the one alarm off but I shook the alarm and it turned off. It can happen but it’s rare.
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That probably had to do with the reverse polarity supervisory current passing through the device.
That was an add-on to the quoted myth.
I think it would be better phrased as an initiating device instead of a notification appliance. Do you mean how people think lifting the cover activates all the fire alarms?
I’ve been thinking about how hitting a notification appliance with a basket ball could cause it to sound.
First of all the reverse polarity supervisory current does not go through the devices. It is blocked by a diode because the purpose of the reverse polarity is to supervise the wiring, not the devices. If some supervisory current does go through a device that is leakage which shunts current around the EOLR. Enough leakage causes the circuit to show a short condition at the panel.
Now for how could that happen? The Truealert NA could be an addressable unit. On an addressable NAC the polarity does not reverse. Supervision is done by poll and reply. Addressable TA devices have test feature that can be activated with a magnet. The device has a magnetic reed switch on the circuit board to activate the test. Those are very small and the reeds inside the glass tube are quite close together. I have seen magnetic reed switches that are sensitive to physical shock. If jarred hard enough they can close the circuit. In the case of the basketball hitting the device the test feature could have been activated. That is the only way I can figure this happened.
Attempted to add this. However, posts seem to be “one shot” with no editing allowed.
Very little current is available in reverse polarity supervisory mode. It is not enough to sound a device. Have had to troubleshoot circuits that have a device connected backwards. All that happens is that the panel shows a short on that circuit. Have to wire the circuit to a 24 volt source backwards so the incorrectly connected device will sound if a horn or flash if a strobe.
I meant people think the Stopper is the alarm.
It’s a Big 4010 System. So it’s addressable.
When were the signals installed? Addressable notification has only been around for a few years.
I think the system was refitted in 2013. This is the system (If anyone remembers my 113 Troubles thread) That got struck by lightning and had the system replaced.
There’s a misbelief that smoke detectors in public facilities will make noise and even shoot out water or CO2 gas through the slits after being activated by smoke.
Some British smoke detectors do have built-in horn strobes, and in some cases sounder bases are used to add audible signals for smoke detectors, but that’s not the most common case. When it comes to “shooting out water or CO2”… That couldn’t be more false.
Technically they are sounders, but I agree with you