Wiring for smoke exhaust fan.

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dahualin

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Is there any special requirement for the wiring to smoke exhaust fan? I have checked the Art. 695.6(B) about circuit conductors for fire pump. It requires a listed electrical circuit protective system with a minimum 1-hour fire rating. Is EMT 1-hour fire rated? Do I have to use MI cable for this application? There are a lot of smoke exhaust fans on roof. Thanks.
 
e57

e57

Senior Member
Location
San Francisco, CA
dahualin said:
Is EMT 1-hour fire rated? Do I have to use MI cable for this application?
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I do not beleive that any wiring method has a fire rating...???? The construction around it would have a fire rating in most cases.

Not a "FIRE" expert, but one would think that a "smoke" exaust fan would not be run perpetually as would a fire pump would be a means to put out the fire, and would need to be run to the bitter end as required by the code you mentioned. A "smoke" exaust being fully invloved in fire would only aid the fire, as a means of travel after it finished exausting the "smoke"... One might want it on with a fire in the area, but not to continue while on fire inifinately.

What is this "Smoke Exaust Fan" for?

Most that I have installed have been fine with using whatever wiring method allowed in the building type. Often EMT/MC... Where I am all FA systems are in EMT, but the fans are not 'part' of the alarm system. The duct detectors would be...
 
infinity

infinity

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Location
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Are we speaking of a smoke purge fan used to remove the smoke after a fire? If so I believe that EMT is permitted as a wiring method. This has nothing to do with the requirements for fire pumps. Those require concrete encased RMC or MI cable to achieve their fire rating.
 
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dahualin

Senior Member
Yes, we are talking about smoke purge fans. I thought the smoke exhaust fan is also life safety equipment. But NEC doesn't cover it. So I thought of fire pump. Thanks.
 
M

mauk

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Location
NY
Occupation
Electrical Engineer
dahualin said:
Yes, we are talking about smoke purge fans. I thought the smoke exhaust fan is also life safety equipment. But NEC doesn't cover it. So I thought of fire pump. Thanks.
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I believe smoke evac fans are listed under critical branch equipment. Is that just for health care facilities?
 
steve66

steve66

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Location
Illinois
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Engineer
If you look in the IBC, there are "smoke control systems", and then there are "smoke and heat vents."

Smoke control systems require two sources of power, all wiring in conduit (regardless of voltage) and the standby power source and transfer switch has to be in a room with a 1-hour rating separate from the normal source.

Smoke and heat vents only require one source, but wiring must be protected aginst temps of 1000F for 15 min.

See the IBC for more.

Steve
 
sceepe

sceepe

Senior Member
Mechanical Engineer in my office specs a smoke control fan that is rated to run for 5 hours at 500 degrees. I told him that was nice but the wiring to the fan is not required to be anything special. Wonder if I should have derated for high ambient temp???:) :-? :)
 
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