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#101377 - 03/13/07 09:38 AM Smoke detectors in HVAC ducts  
sudsy4  Offline
Member
Joined: Apr 2002
Posts: 32
Elizabeth,PA USA
On the job I'm on, the smoke detectors in the HVAC ducts are powered from the convienience outlets in the RTU's. I don't have a copy of NFPA 72, but this doesn't seem like a good idea to me. Should any one trip or turn off a breaker for these outlets there is an alarm initiated. Any info will be appreciated.


Bill

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#101378 - 03/13/07 01:10 PM Re: Smoke detectors in HVAC ducts  
rad74ss  Offline
Member
Joined: Apr 2004
Posts: 156
Pryor, OK USA
I can't site a specific code but the equipment my company manufactures requires the entire smoke circuit to be operated off of a dedicated fire circuit. That includes the fire/smoke detectors, CO detectors, smoke purge and blower interlocks. If there is an outlet somebody is going to plug a drill into it eventually and depending on the fuse or circuit breaker size pop the circuit.

Edited out CO2 I must have been craving a soda.


#101379 - 03/13/07 02:37 PM Re: Smoke detectors in HVAC ducts  
earlydean  Offline
Member
Joined: Dec 2003
Posts: 751
Griswold, CT, USA
NFPA 72 requires:

"Fire alarm systems shall be provided with at least two independent and reliable power supplies, one primary and one secondary." and:

"Connections to the light and power service shall be on a dedicated branch circuit." and:

"The OC device shall have a red marking, shall be accessible only to authorized personnel, and shall be identified as 'FIRE ALARM CIRCUIT CONTROL'."


Earl

#101380 - 03/13/07 02:39 PM Re: Smoke detectors in HVAC ducts  
earlydean  Offline
Member
Joined: Dec 2003
Posts: 751
Griswold, CT, USA
Also, that would be CO detectors, not CO2.


Earl

#101381 - 03/15/07 12:45 AM Re: Smoke detectors in HVAC ducts  
Elviscat  Offline
Member
Joined: Aug 2005
Posts: 214
Seattle Washington USA
would a CO2 detector be what they use to track gases that cause global warming? j/k


#101382 - 03/15/07 07:52 AM Re: Smoke detectors in HVAC ducts  
ghost307  Offline
Member
Joined: May 2005
Posts: 915
Chicago Illinois USA
CO is what they're concerned with; carbon monoxide is much more deadly than carbon dioxide (although they're both bad news in the appropriate concentrations).


Ghost307

#101383 - 03/17/07 09:41 PM Re: Smoke detectors in HVAC ducts  
Mark20  Offline
Member
Joined: Mar 2007
Posts: 25
Maryland
be sure the power source isn't gfi protected (760.21)



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