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Warning Lamps & Beacons

Warning lamps, beacons and light bars make service and work vehicles visible, and they are tested and classed under SAE standards. This sheet covers lamp styles, SAE classes, color rules and what to ask when quoting.

Ref FA-0022SAE J845SAE J595

Draft, open for review. Check every value against the governing standard and the manufacturer’s data before use.

What it is

Warning lamps are optical warning devices mounted on tow trucks, utility and service bodies, plows, pilot cars, construction vehicles and fleets. They include rotating beacons, strobe and LED beacons, mini-bars, full light bars, directional arrows and surface-mount flashers. SAE J845 covers 360° optical warning devices for authorized emergency, maintenance and service vehicles and sets light output classes. SAE J595 covers directional flashing optical warning devices for the same vehicles. Lamp color use is set by state law. Amber is the general color for maintenance and service vehicles. Red and blue are restricted to emergency vehicles in most states.

How to identify

Read the lamp label and package. It shows the SAE standard, class, color, voltage range, flash patterns and mounting style. Beacons are single 360° units. Light bars are long multi-head assemblies. Directional lamps aim forward or rearward rather than all around.

Lamp types and classes

Item	What it is	Notes
Rotating beacon	Reflector or LED pattern that sweeps 360°	Classic style; mechanical units have wear parts
Strobe beacon	Flash tube flash	Being replaced by LED in most lines
LED beacon	LED flash patterns, 360°	Low current draw; many patterns
Mini light bar	Short bar, 360°	Cab roof mount
Full light bar	Long bar, 360° plus work or alley lights	Often with traffic advisor sections
Directional lamp or surface mount	Forward or rear facing flashers	Rated under SAE J595
SAE J845 Class 1	Highest light output class	Often required by DOT or contractor specs
SAE J845 Class 2	Middle class	General service use
SAE J845 Class 3	Lowest class	Light duty

Key points

Customer specs often name the SAE class. Do not substitute a lower class.
Check state law and the customer's policy for color. Selling red or blue lamps for non-emergency use can put the buyer out of compliance.
Mounting options include permanent bolt, magnetic, pipe mount and DIN or vacuum mounts. Magnetic mounts are for temporary use and limited speed per the maker.
Many LED lamps sync together. Confirm the sync wiring and pattern options when mixing models.
Size wiring and protection from the lamp maker's current draw data.

Common mistakes

Selling a Class 2 or 3 lamp where the contract requires Class 1.
Mixing brands that do not sync and producing random flashing.
Mounting a beacon where cab equipment blocks part of the 360° pattern.
Using magnetic mounts on vehicles that run at highway speed for long periods.

Governing standards: SAE J845 (optical warning devices for authorized emergency, maintenance and service vehicles); SAE J595 (directional flashing optical warning devices). State vehicle codes for color and use.

Reference only. Verify against the current governing code or standard, the manufacturer's data and the project documents before use. Apps for Distributors disclaims liability arising from reliance on this reference.

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