Kitchen Hoods and Shunt Trips

Status
Not open for further replies.
charlie b

charlie b

Moderator
Staff member
Location
Lockport, IL
Occupation
Semi-Retired Electrical Engineer
I am out of the office for a couple days, and can?t get to my code books. I have a commercial kitchen that has a dishwasher located under a Type I hood. I don?t know the difference between Type I and Type II hoods, and I don?t know why the dishwasher has a hood over it. But we are being told that because it is under a hood, it must have a shunt trip breaker that is controlled through the fire alarm system. I can?t see why, as it is not a heating appliance.

Question 1: Where does the requirement for shunt trips come from? A fire-related NFPA code?

Question 2: Does the NEC have anything to say about shunt trip requirements?
 
Dishwashers generally only need a class 2 hood if one is needed but the requirements for electric shut down for a class 1 hood can be found in the IBC 2012 as you can see shut down is only required for cooking appliances not all electric needs to shut down. There are separate requirements for make up air shut down but that was not part of your question.

[F] 904.11.2 System interconnection.
The actuation of the fire suppression system shall automatically shut down the fuel or electrical power supply to the cooking equipment. The fuel and electrical supply reset shall be manual.
 
Thanks, Rick. Can you enlighten me as to the nature of a Type I versus a type II?
 
charlie b said:
Thanks, Rick. Can you enlighten me as to the nature of a Type I versus a type II?
Click to expand...

Type I hoods are desiged to remove "grease laden vapors" created by cooking appliances such as deep fryers, flat plate griddles, range tops, tilt skillets, etc. Type II hoods are designed to remove heat or steam. Pizza ovens and commercial dish washers go under Type II hoods.

If the 2012 requirements are as quoted, this is a step down from previous requirements. It used to be that power had to be removed from everything under the hood. I once had to put a convenience receptacle that had a wall clock plugged into it on a shunt trip breaker, because the receptacle was under the hood.
 
SECTION 505 {IFGC}
DIRECT-VENT, INTEGRAL VENT, MECHANICAL VENT AND VENTILATION/EXHAUST HOOD VENTING
505.1 General. The installation ofdirect-vent and integral vent appliances shall be in accordance with Section 503. Mechanical venting systems and exhaust hood venting systems shall be designed and installed in accordance with Section 503.
505.1.1 Commercial cooking appliances vented by exhaust hoods. Where commercial cooking appliances are vented by means of the Type I or II kitchen exhaust hood system that serves such appliances, the exhaust system shall be fan powered and the appliances shall be interlocked with the exhaust hood system to prevent appliance operation when the exhaust hood system is not operating. The method of interlock between the exhaust hood system and the appliances equipped with standing pilot burner ignition systems shall not cause such pilots to be extinguished. Where a solenoid valve is installed in the gas piping as part of an interlock system, gas piping shall not be installed to bypass such valve. Dampers shall not be installed in the exhaust system.
Exception: An interlock between the cooking appliance( s) and the exhaust hood system shall not be required where heat sensors or other approved methods automatically activate the exhaust hood system when cooking operations occur.
IFC
Type I. A kitchen hood for collecting and removing grease vapors and smoke.
IMC
HOOD. An air intake device used to capture by entrapment, impingement, adhesion or similar means, grease, moisture, heat and similar contaminants before they enter a duct system.
Type I. A kitchen hood for collecting and removing grease vapors and smoke. Such hoods are equipped with a fire suppression system.
Type II. A general kitchen hood for collecting and removing steam, vapor, heat, odors and products of combustion.
 
Type 1 hoods include a little more than grease ladden vapors. The requirement for electric shut down has been around for some time and has often been incorrectly enforced. The idea is to shut down the heat sources under the hood to prevent reignition of the fire. Better luck next time.

IMC 2012
507.2.1 Type I hoods.
Type I hoods shall be installed where cooking appliances produce grease or smoke as a result of the cooking process. Type I hoods shall be installed over medium-duty, heavy-duty and extra-heavy-duty cooking appliances. Type I hoods shall be installed over light-duty cooking appliances that produce grease or smoke.

LIGHT-DUTY COOKING APPLIANCE. Light-duty cooking appliances include gas and electric ovens (including standard, bake, roasting, revolving, retherm, convection, combination convection/steamer, countertop conveyorized baking/finishing, deck and pastry), electric and gas steam-jacketed kettles, electric and gas pasta cookers, electric and gas compartment steamers (both pressure and atmospheric) and electric and gas cheesemelters.
MEDIUM-DUTY COOKING APPLIANCE. Medium-duty cooking appliances include electric discrete element ranges (with or without oven), electric and gas hot-top ranges, electric and gas griddles, electric and gas double-sided griddles, electric and gas fryers (including open deep fat fryers, donut fryers, kettle fryers and pressure fryers), electric and gas conveyor pizza ovens, electric and gas tilting skillets (braising pans) and electric and gas rotisseries.
HEAVY-DUTY COOKING APPLIANCE. Heavy-duty cooking appliances include electric under-fired broilers, electric chain (conveyor) broilers, gas under-fired broilers, gas chain (conveyor) broilers, gas open-burner ranges (with or without oven), electric and gas wok ranges, and electric and gas over-fired (upright) broilers and salamanders.
EXTRA-HEAVY-DUTY COOKING APPLIANCE. Extra-heavy-duty cooking appliances include appliances utilizing solid fuel such as wood, charcoal, briquettes, and mesquite to provide all or part of the heat source for cooking.
 
Last edited:
Type 2
507.2.2 Type II hoods.
Type II hoods shall be installed above dishwashers and appliances that produce heat or moisture and do not produce grease or smoke as a result of the cooking process, except where the heat and moisture loads from such appliances are incorporated into the HVAC system design or into the design of a separate removal system. Type II hoods shall be installed above all appliances that produce products of combustion and do not produce grease or smoke as a result of the cooking process. Spaces containing cooking appliances that do not require Type II hoods shall be provided with exhaust at a rate of 0.70 cfm per square foot (0.00033 m3/s). For the purpose of determining the floor area required to be exhausted, each individual appliance that is not required to be installed under a Type II hood shall be considered as occupying not less than 100 square feet (9.3 m2). Such additional square footage shall be provided with exhaust at a rate of 0.70 cfm per square foot [.00356 m3/(s ? m2].
 
Type 1 hood not required and the dishwasher not part of the commercial cooking equipment. Unless the dishwasher is under the same hood, that serves cooking appliances, which has a fire extinguishing system, IMO there is no requirement for a shunt trip.

2009 IMC SECTION 507 COMMERCIAL KITCHEN HOODS
507.2.2 Type II hoods. Type II hoods shall be installed above dishwashers and light-duty appliances that produce heat or moisture and do not produce grease or smoke, except where the heat and moisture loads from such appliances are incorporated into the HVAC system design or into the design of a separate removal system. Type II hoods shall be installed above all light-duty appliances that produce products of combustion and do not produce grease or smoke. Spaces containing cooking appliances that do not require Type II hoods shall be ventilated in accordance with Section 403.3. For the purpose of determining the floor area required to be ventilated, each individual appliance that is not required to be installed under a Type II hood shall be considered as occupying not less than 100 square feet (9.3 m2).
 
Status
Not open for further replies.
Top