FA Fan Shutdown

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mstrlucky74

Senior Member
Location
NJ
Need a little clarity on fan shutdown fire alarm wiring.. In short to activate shutdown is it wiring from fire alarm relay to a starter, vfd or control panel. I know there is sometimes conflict as to who does the wiring from the relay to mechanical equipment...fa contractor or mech guy.
 

ron

Senior Member
Agreed in part: To activate shutdown is it wiring from fire alarm relay to a starter or vfd. You can only wire from fire alarm relay to a control panel if the control panel is actually a starter or VFD, or if it is a BMS control panel, it would have to be listed for smoke control.

They do not want a regular BMS to be responsible for fan shutdown if it is not listed for smoke control (more rubust than just BMS)
 

JoeyD74

Senior Member
Location
Boston MA
Occupation
Electrical contractor
Need a little clarity on fan shutdown fire alarm wiring.. In short to activate shutdown is it wiring from fire alarm relay to a starter, vfd or control panel. I know there is sometimes conflict as to who does the wiring from the relay to mechanical equipment...fa contractor or mech guy.

While it could be in the mechanical company's contract to do all the wiring it should be done by an electrician or alarm guy
 

gadfly56

Senior Member
Location
New Jersey
Occupation
Professional Engineer, Fire & Life Safety
Need a little clarity on fan shutdown fire alarm wiring.. In short to activate shutdown is it wiring from fire alarm relay to a starter, vfd or control panel. I know there is sometimes conflict as to who does the wiring from the relay to mechanical equipment...fa contractor or mech guy.

Usually the fire alarm contractor will supply an addressable relay that will trigger on a general alarm input or a specific device. For a roof top unit, it is common for the relay to break the thermostat connection and this usually shuts down the fan. If you are interrupting more than a few amps, an interposing relay whose coil current is supplied through the addressable relay. The interposing relay is usually rated for 10 amps or up. Or it could be a multi-pole contactor. In order to keep things straight, the FA contractor may run leads for the relay to a terminal block in a junction box, labeled for NC, NO, and C. That way the electrician isn't actually touching any of the fire alarm components.
 
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