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Smoke detectors in HVAC ducts #101377
03/13/07 08:38 AM
03/13/07 08:38 AM
S
sudsy4  Offline OP
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
2017 / 2014 NEC & Related Books and Study Guides
Re: Smoke detectors in HVAC ducts #101378
03/13/07 12:10 PM
03/13/07 12:10 PM
R
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.

Re: Smoke detectors in HVAC ducts #101379
03/13/07 01:37 PM
03/13/07 01:37 PM
E
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
Re: Smoke detectors in HVAC ducts #101380
03/13/07 01:39 PM
03/13/07 01:39 PM
E
earlydean  Offline
Member
Joined: Dec 2003
Posts: 751
Griswold, CT, USA
Also, that would be CO detectors, not CO2.


Earl
Re: Smoke detectors in HVAC ducts #101381
03/14/07 11:45 PM
03/14/07 11:45 PM
E
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

Re: Smoke detectors in HVAC ducts #101382
03/15/07 06:52 AM
03/15/07 06:52 AM
G
ghost307  Offline
Member
Joined: May 2005
Posts: 926
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
Re: Smoke detectors in HVAC ducts #101383
03/17/07 08:41 PM
03/17/07 08:41 PM
M
Mark20  Offline
Member
Joined: Mar 2007
Posts: 25
Maryland
be sure the power source isn't gfi protected (760.21)


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