Fire/smoke dampers dedicated circuit

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gadfly56

Senior Member
Location
New Jersey
Occupation
Professional Engineer, Fire & Life Safety
I always thought that smoke/fire dampers had to be on a dedicated circuit , but now I'm having trouble finding it. Am I incorrect in this?

I have found the fire alarm circuit is required to have it.

Where is the requirements for the smoke dampers?

I do not believe they necessarily have to be dedicated, but they will probably need emergency power unless they are fail closed. The problem with fail closed of course is that if the power to the damper fails and the power to the fan does not, you can turn your square duct into a round duct right quick, or rupture it entirely. What I've usually seen is power dedicated to the FSD's but a circuit serves multiple FSD's, depending on location and also being on emergency power. You may also have to interlock the fan to the FSD to shutdown the fan if the FSD starts to close before the fan gets a shut down signal from its controller.
 
fire smole dampers requirements

fire smole dampers requirements

Hi, I would like to know if Fire smoke Dampers that are above ceiling require remote alarm indicator.
this Smoke Dampers are part of the Dedicated Smoke Control System in a Hospital.
Can you please advice
 

rlundsrud

Senior Member
Location
chicago, il, USA
They are always fail closed, if power is lost they close. They don't have to be on a dedicated circuit but it is a good idea. The end switches from them should kill the air handler.

No, they don't require any notification/alarming points.
 

Fulthrotl

~Autocorrect is My Worst Enema.~
They are always fail closed, if power is lost they close. They don't have to be on a dedicated circuit but it is a good idea. The end switches from them should kill the air handler.

No, they don't require any notification/alarming points.

legacy stuff, not necessarily.

chloride pyrotector systems have a fusible link that takes
a 12 volt small current, and ruptures a bladder inside a cartridge,
and it gets hot and melts the fire link in the drop chain.

resetting it, requires getting to the damper and putting a new fuse
link in, and wiring it in.

and, a 9 volt battery on an ohm meter, applied across those leads,
can trigger them.

i watched a journeyman drop a whole floor of them, one zone at a time,
while "testing" the system. every time he'd operate the test key, there
was this odd thumping sound.

he dropped about 80 zones in a hospital, three days before opening
of the hospital. 300+ dampers.

lotta overtime.
 

gadfly56

Senior Member
Location
New Jersey
Occupation
Professional Engineer, Fire & Life Safety
They are always fail closed, if power is lost they close. They don't have to be on a dedicated circuit but it is a good idea. The end switches from them should kill the air handler.

No, they don't require any notification/alarming points.

If a particular FSD is in the exhaust path for a smoke control system, it may fail open.
 

Strathead

Senior Member
Location
Ocala, Florida, USA
Occupation
Electrician/Estimator/Project Manager/Superintendent
I do not believe they necessarily have to be dedicated, but they will probably need emergency power unless they are fail closed. The problem with fail closed of course is that if the power to the damper fails and the power to the fan does not, you can turn your square duct into a round duct right quick, or rupture it entirely. What I've usually seen is power dedicated to the FSD's but a circuit serves multiple FSD's, depending on location and also being on emergency power. You may also have to interlock the fan to the FSD to shutdown the fan if the FSD starts to close before the fan gets a shut down signal from its controller.


I am pretty sure that all fire/smoke dampers are fail closed. Even if it is on emergency power. I don't do too much research in to the 100 or so other NFPA codes, but I am pretty sure it is in there.
 

CarlosRGNS

New User
Location
New York
Occupation
Engineer
They are always fail closed, if power is lost they close. They don't have to be on a dedicated circuit but it is a good idea. The end switches from them should kill the air handler.

No, they don't require any notification/alarming points.

This makes sense to me. but do you know of an IFC or NEC section that would allow it?
 
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