As an underwriter, you‘ll benefit from the guidelines presented here—intended to help you work successfully with your insureds to identify, reduce, or eliminate hazardous conditions.

Cooking hazards can cause serious fires and place lives at risk. Fires produce more than $10 billion of damage and kill more than 3,000 people every year in the United States. To protect against the loss of life and prevent losses to both the insurer and insured, underwriters need to be aware of the wide range of potential cooking hazards. By identifying those hazards, underwriters and loss control departments can work together to help insureds improve the safety of their cooking establishments.

You can find hazardous cooking conditions not only in normal cooking facilities, such as restaurants, diners, and taverns, but also in other occupancies, such as schools, hospitals, and nursing homes.

Cooking equipment

Cooking equipment that’s improperly installed, maintained, or used represents a potential for major losses. To minimize losses, underwriters should determine whether cooking equipment and related items comply with National Fire Protection Association (NFPA) Standard 96. The standard covers cooking equipment that produces smoke and grease-laden vapors and includes fryers, grills, broilers, charbroilers, stoves or ranges, and kettles (large open vats that use gas, electricity, or steam for cooking). Fryers are one of the most common sources of fires involving cooking equipment.

Limited cooking equipment

Limited cooking equipment, which includes hot dog rollers, infrared warmers, toasters, coffeemakers, and steam tables—can also be hazardous, even though those devices don't produce grease-laden vapors.


Commercial cooking equipment producing grease-laden vapors

Cooking equipment clearances

When evaluating cooking equipment, you must consider how close the equipment is to combustible materials, such as plywood walls, wooden cupboards or shelving, and grease filters. The list below shows appropriate clearances.

Listed appliances to combustible material

  • Per manufacturer specifications

Unlisted appliances to combustible material

  • Minimum of 6 inches

All appliances

  • 24 inches to filters if no exposed flames
  • 36 inches to filters if flames exposed
  • 48 inches to filters for charbroilers

National Fire Protection Association

Scorched walls and grease around hood indicate inadequate clearances

Exhaust systems

An exhaust system consists of a hood or canopy, a fan and duct system, and grease-removal equipment.

Exhaust systems should meet the following clearance criteria:

  • Minimum of 18 inches from hoods and ducts to combustible material
  • Minimum of 6 inches to noncombustible material if duct is enclosed
  • Minimum of 10 inches from outlet to adjacent buildings
  • Minimum of 10 inches from outlet to air intakes, space permitting


Properly designed hood

Hoods should be made of stainless or carbon steel or other approved fire-resistant material. They should extend completely over all equipment that produces grease-laden vapors.


A typical fan duct system

A duct system is a passageway that transmits grease-laden vapors to the outside. Ducts should consist of fire-resistant materials, be isolated from other exhaust or ventilation systems, and lead directly to the exterior. Qualified personnel should also maintain and clean ducts regularly.


Fire wrap is an acceptable duct insulation

Fans move air and grease-laden vapors to the duct system. Fans and motors should be UL listed for use in grease-laden atmospheres and have blades of nonferrous metal, such as aluminum.


Grease filters and extractors

Those systems help rid hoods of grease. Commercial cooking operations require metal filters. They should be UL-listed.

Hazardous accumulation of grease in the exhaust system

Hazardous accumulation of grease in the hood and duct

Exhaust system schematic

Here's a schematic diagram of a typical cooking exhaust system, courtesy of the National Fire Protection Association (NFPA). The schematic shows the components of an exhaust system and required roof clearances.

Reprinted with permission from NFPA 96, Ventilation Control and Fire Protection of Commercial Cooking Operations, Copyright ©2004, National Fire Protection Association, Quincy, MA 02169. This reprinted material is not the complete and official position of the National Fire Protection Association on the referenced subject, which is represented only by the standard in its entirety.

What is fire?

Fire is a series of chemical chain reactions that break fuel down into pieces and result in waste products of carbon dioxide, carbon monoxide, water vapor, unburned fuel or smoke, and other chemicals.

You can stop a fire in the following ways:

  • Remove the heat source (dousing with water, for example)
  • Cut off the oxygen (such as putting a lid on burning grease)
  • Use extinguishing chemicals (such as those found in fire extinguishers)

The table above shows the four classes of fire, with examples of each below.


Flames flaring up in a restaurant cooking area

Class A burn of cardboard boxes

Class B burn of flammable liquids

Extinguishing systems

The class of fire determines the type of extinguishing agent used. Commercial kitchens use five types of automatic extinguishing systems.

Automatic sprinklers

The building should install sprinklers according to NFPA standards. Sprinklers protecting cooking equipment require separate control valves.

Dry chemical systems

Dry chemicals such as sodium or potassium bicarbonate can extinguish Class B and C fires. Those systems extinguish fires by interrupting the chemical reaction. However, because hot surfaces aren't cooled, reignition can occur.

Wet chemical systems

Wet chemicals are water-based solutions made of potassium carbonate and are used to extinguish Class A and B fires. The solution mixes with grease and forms a soapy mixture that cools and smothers the fire. There's less chance of reignition.

Carbon dioxide (CO2) systems

These systems function by flooding the fire area with carbon dioxide, smothering the fire. Because of increasing concerns of dangerous health effects at high exposure levels, CO2 systems are becoming rare.

Automatic extinguishing system

Below are the Components of an automatic extinguishing system.

Storage cylinder

Pressurized gas in the cylinder forces chemicals out to extinguish fire. Underwriters need to ensure that the pressure is maintained at the proper level.

Activating devices

An activating device sets off the system in the event of fire. The fusible link is the most common device and requires replacement annually. The system also needs a manual device to activate it in case the automatic device fails. The manual pull should be well marked and located near an exit.

Piping and nozzles

Dry and wet extinguishing systems require different kinds of piping and nozzles. Dry nozzles are larger and usually capped to protect them from grease. Wet nozzles are small and may have a plastic cap on them. Nozzles must point at the equipment they‘re designed to protect.

Automatic fuel shut-off

When the extinguishing system activates, it should automatically shut off the gas or electricity providing heat for cooking.

Manual pull

Automatic shut-off for gas

Installation and maintenance

Underwriters should determine whether a facility has a certificate of installation and a current maintenance contract for its system. New systems and systems not previously recognized require certificates of installation. The certificate indicates that the property has installed the system according to listing and manufacturing instructions. A maintenance contract should indicate that the system is serviced twice a year.

In the event of a fire or damage to a cooking area, a qualified professional should inspect the risk to determine that the structure and equipment are sound, capable of maintaining their fire protection function, and in compliance with accepted guidelines.

Photo courtesy of Superior Safety

Restaurant hazards

Verisk field representatives go on-site to survey properties with cooking facilities and report on cooking hazards we've described here.


We also review other areas that can affect a property's potential losses:

  • Type of entertainment — Does the restaurant have a band, dancing, or amusement devices, such as video games?
  • Alcoholic beverages — How much alcohol does the facility sell or consume?
  • Emergency lights — Do emergency lights operate when the electricity fails?
  • Exits — Are exits accessible and properly marked?
  • Pest control — Do qualified personnel conduct regular pest control?
  • Food delivery — How's food kept hot or cold during the delivery process? Are driving records of drivers checked?
  • Food storage — Is food refrigerated or frozen properly?
  • Parking — Is the lot well lit? Is there valet parking?
  • Tripping hazards — Are there sufficient handrails? Are floor surfaces highly waxed or polished? Is there adequate lighting?
  • Snow and ice removal — Does building management keep walks, steps, and parking lots free of snow and ice?
  • Licenses — Does the restaurant have proper licenses?

Verisk also collects information on:

  • Sales value of the items sold in the restaurant facility
  • All kitchen equipment
  • Construction of the building
  • Heating and electrical systems
  • Fire protection
  • Crime protection

Parking lot lighting

Underwriter's checklist for cooking hazards

  1. Have personnel installed cooking equipment, grease removal systems, and extinguishing systems according to the manufacturer’s instructions and the standards of the NFPA, the American Gas Association, or UL?
  2. Are cooking areas and exhaust systems clean and free from grease buildup?
  3. Do cooking equipment and exhaust systems have adequate clearance from combustible materials?
  4. Does the hood cover the cooking area?
  5. Is all electrical equipment, including fans, approved for use in a grease-laden atmosphere?
  6. Is there a certificate of installation and a current maintenance agreement for the extinguishing system?
  7. Has an automatic fuel shut-off been installed and connected?
  8. Is a manual activation device for the extinguishing system located in an exit path?
  9. Are extinguishers installed and maintained in accordance with NFPA standards?

Additional resource

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