Truck Emergency Equipment and Warning Triangle Rules
Every truck, truck tractor and bus must carry a fire extinguisher and warning devices (49 CFR 393.95). A power unit with no placarded hazmat needs one 5 B:C extinguisher or two 4 B:C, plus three reflective triangles or six fusees. When a CMV stops on a road or shoulder, the driver turns on the hazard flashers at once and sets out the warning devices within 10 minutes (49 CFR 392.22). Spare fuses are no longer required.
Facts checked October 17, 2026
Key Points
- A power unit that hauls placarded hazmat needs a fire extinguisher rated 10 B:C or more. Any other power unit needs one rated 5 B:C or more, or two rated 4 B:C or more each (49 CFR 393.95(a)(1))
- The extinguisher must show its rating, show whether it is fully charged, be easy to reach, and be mounted so it cannot slide or roll (49 CFR 393.95(a))
- For warning devices, a truck carries either three bidirectional reflective triangles that meet FMVSS 125, or at least 6 fusees (49 CFR 393.95(f))
- Spare fuses are no longer required. FMCSA removed that rule effective April 20, 2026. References to liquid-burning flares were removed effective March 23, 2026
- A CMV stopped on a road or shoulder for any reason other than a necessary traffic stop must turn on the hazard flashers right away, and put out the warning devices as soon as possible and within 10 minutes (49 CFR 392.22)
- On a two-way road, the three devices go 10 feet and 100 feet from the truck toward approaching traffic, and 100 feet from the truck the other way (49 CFR 392.22(b)(1))
- Fusees and other flame devices may not be carried on a vehicle with Division 1.1, 1.2 or 1.3 explosives, on a cargo tank for flammable gas or flammable liquid, or on a vehicle that uses compressed gas as fuel (49 CFR 393.95(g))
Where to put the warning devices when a truck is stopped (49 CFR 392.22(b))
| Where you are stopped | Where the devices go | |
|---|---|---|
| Two-way road or shoulder | One on the traffic side, 10 feet from the truck, toward approaching traffic. One 100 feet from the truck toward approaching traffic. One 100 feet from the truck in the other direction. The two 100-foot devices go in the center of your lane or shoulder. | |
| Divided or one-way road | One 200 feet and one 100 feet from the truck toward approaching traffic, in the center of your lane or shoulder. One on the traffic side within 10 feet of the rear of the truck. | |
| Within 500 feet of a curve, a hill crest or other view block | Put the warning in the direction of the obstruction, 100 to 500 feet from the truck. | |
| Business or residential district of a town | Not required, unless lights are required and the street lighting is too weak to see the truck from 500 feet. | |
| Fusees only | Light one fusee at each place. Keep at least one lit at each place while the truck is stopped. Put each one out and pick it up before you move. |
What emergency equipment must a truck carry?
Each truck, truck tractor and bus must carry a fire extinguisher and warning devices for stopped vehicles (49 CFR 393.95). The rule does not apply to a vehicle towed in a driveaway-towaway operation, and the extinguisher rule does not apply to the driven unit in that kind of operation. The rule lists the ratings, the labels, how the extinguisher must be mounted, and what warning devices count. This section does not list a first aid kit, a flashlight or tire chains. Many carriers add them anyway.
What size fire extinguisher does a truck need?
It depends on the load. A power unit used to haul hazmat in a quantity that needs placards must carry an extinguisher rated 10 B:C or more. A power unit that does not haul hazmat needs either one extinguisher rated 5 B:C or more, or two extinguishers each rated 4 B:C or more (49 CFR 393.95(a)(1)). The maker must label each extinguisher with its Underwriters' Laboratories rating. It must show by sight whether it is fully charged. It must be filled and placed where you can reach it, and mounted so it cannot slide, roll or move up and down. The agent must not need protection from freezing.
What warning devices are required?
A truck must carry one of two sets. One set is three bidirectional emergency reflective triangles that meet Federal Motor Vehicle Safety Standard 125. The other set is at least 6 fusees, plus any extra fusees needed to meet the 392.22 placement rules (49 CFR 393.95(f)). You may carry other warning devices as well, but only if they do not make the required devices less effective. Fusees must burn for 30 minutes and meet UL 912. Red flags, if used, must be at least 12 inches square on upright standards. Fusees and any flame signal may not be carried on a vehicle with Division 1.1, 1.2 or 1.3 explosives. They may not be carried on a cargo tank used for Division 2.1 flammable gas or Class 3 flammable liquid, whether loaded or empty. A vehicle that uses compressed gas as motor fuel cannot carry them either (49 CFR 393.95(g)). Those trucks need triangles.
Are spare fuses still required?
No. FMCSA removed the rule that each CMV carry at least one spare fuse for each type and size of fuse it needs. The final rule was published on February 19, 2026 and took effect April 20, 2026. Older guides may still list spare fuses as required equipment. Another final rule from the same day removed the liquid-burning flare references from the rules. It took effect March 23, 2026. The rule text now names only reflective triangles and fusees.
When must a driver put out the warning devices?
Whenever a commercial motor vehicle is stopped on the traveled part of a highway or the shoulder for any reason other than a necessary traffic stop (49 CFR 392.22). The driver must turn on the hazard flashers immediately and leave them on until the warning devices are out. The flashers go on again while the devices are picked up before the truck moves. The driver must place the devices as soon as possible, and within 10 minutes. Flashers can stay on after that, in addition to the devices, but never in place of them. The rule does not count a necessary traffic stop.
Where do the warning triangles go?
The table above has the layout. On a two-way road, put one triangle on the traffic side about 10 feet from the truck toward oncoming traffic. Put one 100 feet toward oncoming traffic and one 100 feet the other way, both in the center of your lane or shoulder. On a divided or one-way road, put one 200 feet and one 100 feet behind the truck toward traffic, and one within 10 feet of the rear on the traffic side. If the truck is within 500 feet of a curve, a hill crest or something that blocks the view, put the warning that way, 100 to 500 feet from the truck. The rule counts paces, so 4 paces is about 10 feet and 40 paces is about 100 feet.
When are warning devices not required?
Not required in the business or residential district of a town, except when lighted lamps are required and the street or highway lighting is not enough to make the truck easy to see from 500 feet (49 CFR 392.22(b)(2)(iii)). A driver who uses only fusees must keep at least one fusee lit at each place while the truck is stopped, and must put each one out and remove it before moving. If gasoline or another flammable or combustible liquid or gas is leaking, no signal that makes a flame may be lit or put out except far enough from the leak to prevent a fire or explosion (49 CFR 392.22(b)(2)(vi)).
Related Free Tools
Truck Breakdown Triage
Pick what is going wrong and get a clear answer: stop now, get help first, or drive on to the next safe stop. Then copy a message for your broker.
Accident Documentation Kit
A step-by-step form for documenting an accident right away. Time is critical.
Pre-Trip / Post-Trip DVIR Checklist
A 49 CFR 396.11 compliant Driver Vehicle Inspection Report with defect tracking.
Frequently Asked Questions
How many warning triangles does a truck need?+
Three bidirectional reflective triangles that meet Federal Motor Vehicle Safety Standard 125. A truck may carry at least 6 fusees instead, except a vehicle that may not carry flame devices (49 CFR 393.95(f) and (g)).
How far behind a truck do you put the warning triangles?+
On a two-way road, put one 10 feet from the truck on the traffic side toward oncoming traffic, one 100 feet toward oncoming traffic and one 100 feet the other way. On a divided or one-way road, put one 200 feet and one 100 feet behind the truck, and one within 10 feet of the rear (49 CFR 392.22(b)).
How fast must I put out warning triangles after I stop?+
As soon as possible, and within 10 minutes. Turn on the hazard flashers right away and leave them on until the devices are out (49 CFR 392.22(a) and (b)).
What size fire extinguisher is required on a semi truck?+
One rated 5 B:C or more, or two rated 4 B:C or more each, if you do not haul placarded hazmat. A truck that hauls hazmat in a quantity that needs placards needs one rated 10 B:C or more (49 CFR 393.95(a)).
Does DOT still require spare fuses?+
No. FMCSA removed the spare fuse requirement in a final rule that took effect April 20, 2026. A carrier may still ask drivers to carry them (91 FR, Feb. 19, 2026).
Do I need warning triangles in town?+
Not in the business or residential district of a town, unless lighted lamps are required and the street lighting is too weak to see the truck from 500 feet (49 CFR 392.22(b)(2)(iii)).
Can I use road flares on a truck that hauls flammable liquid?+
No. A cargo tank used for flammable gas (Division 2.1) or flammable liquid (Class 3), loaded or empty, may not carry fusees or other flame signals. Use reflective triangles (49 CFR 393.95(g)).
What does the DOT require in a truck besides a fire extinguisher and triangles?+
Part 393 sets rules for lights, brakes, tires and other equipment, and a driver must follow them. The emergency equipment rule in 49 CFR 393.95 names only the fire extinguisher and the warning devices. It does not list a first aid kit or a flashlight.
Are the hazard flashers enough on their own?+
No. The flashers may be used in addition to the warning devices, but not in place of them (49 CFR 392.22(a)).
More federal trucking rules
- Hours of Service Rules for Truck Drivers
- ELD Mandate: Who Needs an ELD
- DOT Roadside Inspection Levels Explained
- DOT Drug and Alcohol Testing Rules
- Driver Qualification File Requirements
- DVIR and Vehicle Maintenance Rules
- New Entrant Safety Audit Requirements
- Hours of Service Exceptions and Exemptions
- Motor Carrier Insurance Requirements
- CDL Classes, Endorsements and ELDT Training
- DOT Physical and Medical Card Requirements
- Drug and Alcohol Clearinghouse Requirements
- Cargo Securement Rules for Trucks
- Hazmat Basics for Truck Drivers and Carriers
- USDOT Number and Biennial Update Requirements
- Safety Ratings, Compliance Reviews and DataQs
- Federal Truck Size and Weight Limits
- California Clean Truck Check (HD I/M)
- Truth-in-Leasing Rules for Owner-Operators
- Form 2290 Heavy Highway Vehicle Use Tax
- Truck Driver Phone, Texting and Seat Belt Rules
- Railroad Crossing Rules for Truck Drivers
- Truck Windshield, Dash Cam and Mirror Rules
- CDL Disqualification: Major and Serious Offenses
- Truck Tire Rules: Tread Depth, Retreads and Pressure
- Trailer Reflective Tape (Conspicuity) Rules
- Truck Brake Rules: Pushrod Stroke, Lining Thickness and ABS
- Driver Conduct Rules: Alcohol, Drugs, Fatigue, Passengers and Pre-Trip Checks
- English Language Proficiency for Truck Drivers: The 391.11(b)(2) Rule
- Weigh Station Rules: Who Must Stop and What Happens If You Skip
- Truck Lighting Rules: Required Lamps and Reflectors (49 CFR 393)
- Driver Road Test Rules: The Company Road Test and Certificate (49 CFR 391.31)
Related terms and pages
Sources
- 49 CFR 393.95, Emergency equipment on all power units (eCFR)
- 49 CFR 392.22, Emergency signals; stopped commercial motor vehicles (eCFR)
- Final rule: Parts and Accessories Necessary for Safe Operation; Spare Fuses, 91 FR, Feb. 19, 2026 (Federal Register)
- Final rule: Parts and Accessories Necessary for Safe Operation; Liquid-Burning Flares, 91 FR, Feb. 19, 2026 (Federal Register)
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This is a plain-language summary for reference, not legal advice. Check the official rule text before you rely on any detail. Ask a compliance professional about your own operation.