Shunt trip for kitchen equipment

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mparkstexas

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Our policy is typically to put all kitchen equipment that is under the hoods on one panel with an MCB. Then note the breaker to be tied into the FA so when it goes off, the MCB trips and kill on the equipment.

Does anyone know how the FA communicates with the MCB? Is it just a low voltage signal? Does anyone know any pros/cons other than saving space on the panel for all the individual shunt trips?

Thanks!
 
Shunt Trip

Shunt Trip

something to keep in mind is that most manufacturers shunt trip breakers take up an additional space to accomodate the shunt trip you could also accomodate this by running the cirucits thu a contactor and controlling the coil via a f.a. contact.
 
Three solutions I have seen:
1. MCB in panel serving under hood has shunt trip or undervoltage trip - shunt operates when voltage is applied by opening the breaker - undervoltage trip has 120V circuit from fire alarm relay which opens when FA activates droping power from the undervoltage coil and preventing the breaker from being closed until power is restored.
2. Feed to panel is broken through a contactor - operating just like undertrip.
3. Mutilple pole contactors are used to break circuits under hood - again operating like the undertrip.
Usually the control circuit is 120VAC on all the above and broken either through NC or NO open contacts on a fire alarm monitoring relay depending on the arrangement needed.

Have a good day!
 
some FA panels might have a set of dry contacts you can connect too. they also might have a set of powered 24vac contacts you can use. depends on who makes the FA panel. do you have the specs of the FACP
 
If the equipment shutting down is cooking appliances, make up air, gas valve etc associated with the fire suppression system (Ansul or equivelent) "Hood System", there is a microswitch (dry contact) inside the suppression system that is only capable of low current coil voltage which trips your contactor, to perform these various shut downs.

The fire alarm in the building does not interface with the kitchen hood fire system or shut down circuits other than simply monitoring the hood system for alarm status:).
 
Mr. Parks, the only concern with tripping the entire panel is that the exhaust fan(s) muct operate (regardless of the manual switch position) and the horn/strobe, if there is one, must operate.

If there are a lot of electrical appliances under the hood, the shunt-trip main breaker can be more economical, and, as you noted, space-saving over individual circuit shunt-trips, but . . .

I do a fair amount of the wiring for retro-fitting of existing hood systems, and have had to tap the panel's incoming conductors to supply a small sub-panel for the fans and the horn-strobe.

I also often use contactors for receptacles and appliances, rather than shunt-trips, especially in retro-fits where no shunt-trips were installed originally. They're much less expensive, and no cable to run back to the panel.

I have several circuits drawn if you need some ideas.
 
STHOMAS said:
. . . there is a microswitch (dry contact) inside the suppression system that is only capable of low current coil voltage which trips your contactor, to perform these various shut downs.
Click to expand...
I beg to differ. Every microswitch I've checked has had at least a 10a contact rating; the newer ones I connect these days are all rated for 16a.

Figuring a once-a-year or so operation for testing, I have no hesitation controlling 120v fan motors directly by the microswitches themselves.

I can control both intake and exhaust motors (or their contactors) by a single microswitch, whether they're controlled by one or two switches.
 
Kitchen Hood Shutdown

Kitchen Hood Shutdown

The shutdown is for the electrical power under the hood only. The hood fire suppression system has a set of dry contacts to operate the MCB with shunt trip or contactor which controls the power under the hood. The fire suppression system will also initiate an alarm at the F/A panel if there is one. Typically the Exhaust hood will remain on however the make-up air fan must shut down on suppression. Our shop just had a big debate on whether or not the hood should shut down so I called a state fire marshall who researched and came back with
"They no longer care if it is on or off" however the make-up air must shut down.

Hope this helps.

LeeB
 
It depends on the fire suppression system. Some require the exhaust as well as the intake fans to be shut down. Always check with the fire suppression manuacturer - they are listed devices.
 
Around here, and everywhere I've heard about, it's exhaust on and everything else off.

We even have to lose the gas during manual exhaust-fan shutdown. Owners hate that.
 
LarryFine said:
I beg to differ. Every microswitch I've checked has had at least a 10a contact rating; the newer ones I connect these days are all rated for 16a.

Figuring a once-a-year or so operation for testing, I have no hesitation controlling 120v fan motors directly by the microswitches themselves.

I can control both intake and exhaust motors (or their contactors) by a single microswitch, whether they're controlled by one or two switches.
Click to expand...


I suppose the micro switch ratings have improved since I have had anything to do with them...its been many years.

INMO if I were invloved in a new design, I would encourage as part of the design to have the microswitch control a contactor, or shunt trip circuit simply because I would not want the hood system service tech near motor voltage (if this is the correct term, I am just a fire guy :) ) Plus there are usually several things that need to happen upon activation of the suppression system. My preference would be to have one switch control shutdown(s), and another to trip the FA system.
 
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