# Brain Tease: NFPA 72



## jar546 (Feb 7, 2011)

Can a smoke detector in an HVAC duct be set to only send a supervisory signal rather than initiate an alarm signal at a protected premises fire alarm system?


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## Coug Dad (Feb 7, 2011)

Many cities require this so the fire department is not dispatched on unwanted alarms.


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## mtlogcabin (Feb 7, 2011)

jar546 said:
			
		

> Can a smoke detector in an HVAC duct be set to only send a supervisory signal rather than initiate an alarm signal at a protected premises fire alarm system?


That is the preferred method hpwever not the only

Activation of a duct smoke detector shall initiate a visible and audible supervisory signal at a constantly attended location and shall perform the intended fire safety function in accordance with this code and the International Mechanical Code . Duct smoke detectors shall not be used as a substitute for required open area detection.

Exceptions:

1. The supervisory signal at a constantly attended location is not required where duct smoke detectors activate the building's alarm notification appliances.


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## cheyer (Feb 7, 2011)

Yes, sir....it is actually preferred... but the catch in CA. is that the supervisory signal must be sent to a constsntly attended location, if not, it should generate a general alarm at the protected premises......but hang on, if this is a brain tease I may be missing something....


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## cheyer (Feb 7, 2011)

MT beat me to it........


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## cda (Feb 7, 2011)

from 2002 edition   ""DEPENDS""

6.15.5.3  Connections between fire alarm systems and the HVAC system for the purpose of monitoring and control shall operate and be monitored in accordance with applicable NFPA standards. Smoke detectors mounted in the air ducts of HVAC systems shall initiate either an alarm signal at the protected premises or a supervisory signal at a constantly attended location or supervising station.


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## Marshal Chris (Feb 8, 2011)

907.11 Duct smoke detectors. Duct smoke detectors shall be connected to the building's fire alarm control panel when a fire alarm system is provided. Activation of a duct smoke detector shall initiate a visible and audible supervisory signal at a constantly attended location. Duct smoke detectors shall not be used as a substitute for required open-area detection.

Exceptions:

1.	The supervisory signal at a constantly attended location is not required where duct smoke detectors activate the building's alarm notification appliances.

2.	In occupancies not required to be equipped with a fire alarm system, actuation of a smoke detector shall activate a visible and audible signal in an approved location. Smoke detector trouble conditions shall activate a visible or audible signal in an approved location and shall be identified as air duct detector trouble.

this is NY version


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## msjenkin (Sep 12, 2022)

I am new to this supervisory signal requirement for duct detectors. can anyone recommend a good spec?


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## Yikes (Sep 13, 2022)

Off-topic: When I was a college student, my next door neighbor decided it would be fun to barbecue meat *inside* his dorm room, on one of those charcoal mini-hibachis.  He didn’t want the smoke to tip off the resident manager, so his brilliant solution was to make sure his window and door were both tightly closed. 

Fortunately for him, the duct serving his room had a smoke detector.  It did not set off the general fire alarm, but it did send a supervisory signal.  Staff called the fire department, and they opened his door to find him passed out from CO.  They managed to revive him.

He was, of course, expelled from the dorm.  After that, his college nickname was “Kingsford".


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