Cooking equipment under commercial kitchen hood

[anbm]

Will kitchen hood' lights, exhaust fan be required shunt trip circuit protection or only cooking equipment located under the hood?

 

[Little Bill]

Can't remember if the lights need to be on the shunt, but the exhaust needs to stay on and make-up air off.

 

[darekelec]

I faintly remember my research that it depended on local codes (not nec).
Same for exhaust air fan.

 

[mopowr steve]

Around here, lights and any appliances off (electric or gas) under hood, but exhaust remains on.

 

[LarryFine]

The usual rules are, when there's a system trip:
The exhaust fan must come on or stay on.
The make-up air fan must turn off or stay off.
All electricity under the hood must lose power.
Electric gas valve: exhaust on, gas reset button.
Mech. gas valve: T-stat w/10-minute exhaust.
Horn/strobe or building alarm connection.

 

[brantmacga]

These are the codes relevant to your question, from NFPA 96 2021 version. You can access the entire code book for free at the NFPA website.

8.2.3.1 A hood exhaust fan (s) shall continue to operate after the extinguishing system has been activated unless the fan shutdown is required by a listed component of the ventilation system or by the design of the extinguishing system.


8.2.3.2* The hood exhaust fan shall start upon actuation of the extinguishing system if the exhaust fan and all cooking equipment served by the fan have been shut down, unless the fan shutdown is required by a listed component of the ventilation system or by the listing of the extinguishing system.

8.2.3.3 The exhaust fan shall be provided with a means so that the fan is activated when any heat-producing cooking appliance under the hood is turned on.

8.3.2 When the fire-extinguishing system activates, makeup air supplied internally to a hood shall be shut off. -- Keep in mind that RTU's may be used for make-up air, and if so, you'll need to shunt the T-stat wire to turn it off.


10.4.1 Upon actuation of any fire-extinguishing system for a cooking operation, all sources of fuel and electric power that produce heat to all equipment protected by the system shall automatically shut off.


10.4.2 Steam supplied from an external source shall not be required to automatically shut off.


10.4.3 Gas appliances not requiring protection but located under the same ventilation equipment where protected appliances are located shall also be automatically shut off upon actuation of the extinguishing system.


10.4.4 Shutoff devices shall required manual resetting prior to fuel or power being restored.


10.4.4.1 Where an electrical gas valve is used for shutting off gas appliances, a manually reset relay shall be used to restore electrical power to the gas valve.


10.4.5 Solid fuel cooking operations shall not be required to be shut down.

 

[GoldDigger]

So, under this set of rules, it is not necessary to cut off power to lighting under the hood (except for heat lamps.)

 

[brantmacga]

That is correct. You only need to disconnect appliances that are heat producing. Some of the restaurants we build have things like POS monitors, and other food processing equipment and coolers that aren’t required to be shunted. Fryers, grills, ovens, etc you would shunt.


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[Grouch]

I can't remember which code it was in, maybe the fuel gas code or building code... it says if the fire suppression system is triggered, and it shuts down the master gas control valve, you don't need to shunt the appliances beneath a hood. Is this right, wrong?

 

[LarryFine]

If you have gas and electricity, they both must shut down.

 

[Grouch]

If you have gas and electricity, they both must shut down.

ok, thanks.

 

[brantmacga]

I can't remember which code it was in, maybe the fuel gas code or building code... it says if the fire suppression system is triggered, and it shuts down the master gas control valve, you don't need to shunt the appliances beneath a hood. Is this right, wrong?

I copy/pasted the code about 5 posts up from here

Electronic control circuits aren’t required to be shunted for gas appliances.

Only electric power used for producing heat.


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[Grouch]

Electronic control circuits aren’t required to be shunted for gas appliances.

So for example, if you have a gas range... that's not required to shut down electrically?

 

[kwired]

State fire marshal is the AHJ for this around here. Don't know what code they use or how well they follow it, but seem to remember last time I was involved with one of those they seemed to be mostly concerned with appliances that typically produce grease laden vapors. Had a griddle and a couple fryers that definitely needed to be shut down by the fire suppression system but also had a household electric range that wasn't even under the hood, and they didn't care much about it. Owner only intended to use it mostly if they were boiling water to cook something or maybe occasionally use the oven.

I think I did have other 120 volt receptacles under hood and did shut them down if fire suppression was activated. What may or may not get plugged into them may or may not have required being shut down but it was somewhat of CYA situation.

 

[brantmacga]

So for example, if you have a gas range... that's not required to shut down electrically?

No

10.4.1 Upon actuation of any fire-extinguishing system for a cooking operation, all sources of fuel and electric power that produce heat to all equipment protected by the system shall automatically shut off.

Only the circuits that are used for producing heat. There are even some grills/fryers we install that have the exhaust interlock built-in, and you have to keep the controls circuit powered while shunting only the heating-element circuits.