What are SAE Class 1 Warning Lights?

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What are SAE Classifications?

The Society for Automotive Engineers (SAE) has developed a standardized classification system for vehicle warning lights, known as SAE Class, which includes three levels: Class 1, Class 2, and Class 3. Before diving into the differences between these classes, it’s important to understand how SAE Class is determined.

SAE Class is based on the SI unit of measurement, Candela. Candela (cd) measures the brightness of light and indicates the intensity of a light beam in a specific direction. The SAE uses candela to assign class rankings because automotive warning lights often rely on focused beams to alert oncoming traffic to potential hazards. Using a measurement like lumens, which measures the total area illuminated by a light, would not be effective. 

When selecting the right light for your application, you may encounter identifiers such as SAE J845, followed by Class 1, Class 2, or Class 3. It's important to understand that these terms refer to the functionality of the light, and the SAE Class ratings are equivalent.

SAE J845 refers to omnidirectional or 360-degree optical warning lights (like a lighthouse or emergency vehicles). The key difference between these categories is the direction of the light—directional lights are visible from a specific direction, while omnidirectional lights are visible from all directions. Despite these differences in light direction, the intensity is measured the same way.

SAE Class 1 warning lights are typically used on emergency response vehicles like police, fire, and ambulance. These lights have a candela value exceeding 8100, with some reaching nearly 18,000 cd-s/m when clearing traffic during emergencies. SAE Class 1 lights are four times more intense than SAE Class 2 lights and ten times more intense than SAE Class 3 lights.