• Each truck, truck tractor, or bus must be equipped with either: (1) a fire extinguisher having a UL rating of 5 B:C or more; or (2) two fire extinguishers, each of which has a UL rating of 4 B:C or more.
• Vehicles, when stopped, must use as a warning device either three bidirectional emergency reflective triangles that conform to the requirements of the applicable FMVSS, or at least six fusees.

All trucks, truck tractors, and buses (except those towed in driveaway-towaway operations) must be equipped with fire extinguishers, and warning devices. (393.95)

Fire extinguishers

Each truck, truck tractor, or bus must be equipped with either (1) a fire extinguisher having an Underwriters’ Laboratories (UL) rating of 5 B:C or more; or (2) two fire extinguishers, each of which has a UL rating of 4 B:C or more. If the vehicle is used to transport hazardous materials in a quantity that requires placarding, it must be equipped with a fire extinguisher having a UL rating of 10 B:C or more.

Each fire extinguisher must:

• Be labeled or marked by the manufacturer with its UL rating.
• Be designed, constructed, and maintained to permit visual determination of whether it is fully charged.
• Be filled and located so that it is readily accessible.
• Be securely mounted to prevent sliding, rolling, or vertical movement relative to the motor vehicle.
• Use an extinguishing agent that does not need protection from freezing.
• Use extinguishing agents that comply with the toxicity provisions of the Environmental Protection Agency’s Significant New Alternatives Policy (SNAP) regulations. (393.95(a))

Warning devices

Vehicles must use one of the following warning devices when stopped:

• Three bidirectional emergency reflective triangles that conform to the requirements of Federal Motor Vehicle Safety Standard (FMVSS) No. 125, 571.125; or
• At least six solid-fuel flares (fusees) and as many additional fusees as necessary.

Other warning devices may be used in addition to, but not in lieu of, the required warning devices. The additional warning devices must not decrease the effectiveness of the required warning devices. When red flags are used as warning devices, they must be at least 12 inches square, with standards adequate to maintain the flags in an upright position. (393.95(f), (k))

Note that at least one specific brand of battery-operated LED light has been approved for use as a warning device in place of the devices mentioned above.

Minimum burning requirements for flares

Each fusee must be capable of burning for 30 minutes. Fusees must conform to the applicable UL requirements and be marked with the UL symbol. (393.95(h))

Hazardous material exception

Liquid-burning flares, fusees, oil lanterns, or any warning signal produced by a flame must not be carried on any:

• Commercial motor vehicle (CMV) transporting Division 1.1, 1.2, or 1.3 (explosives) hazardous materials;
• Cargo tank motor vehicle used for the transportation of Division 2.1 (flammable gas) or Class 3 (flammable liquid) hazardous materials whether loaded or empty; or
• CMV using compressed gas as a motor fuel. (393.95(g))