The Most Common Causes of Fires on Heavy Vehicles

Heavy vehicles, such as trucks, trailers and buses are important company assets and represent a great loss if fire incidents occur. Loss of a heavy vehicle can also be traumatic for the driver and owner. For these reasons, operators should be aware of the most common causes of fire incidents to prevent them from occurring.

The most common causes of truck fires are:

1. Electrical short circuits, especially on unfused and unprotected electrical wiring between the battery, starter motor, and alternator.
2. Fuel line abrasion, damage or failure that results in fuel leaks or aerosols contacting adjacent hot surfaces (e.g. exhaust manifold, or turbocharger).
3. Lubrication, hydraulic oil, or coolant line failures that result in leaks or aerosols contacting adjacent hot surfaces (e.g. exhaust manifold, or turbocharger). These combustible materials have varying autoignition temperatures. When they are released from a high-pressure line as an aerosol, their autoignition temperatures are significantly reduced.
4. Turbocharger failures can cause excessive temperatures in the air intake. For example, failure of the centre bearing can result in the leakage of lubricating oil. Ignition of this oil can cause a fire to start and spread.
5. The accumulation of organic debris, such as leaves, grass, or dust from a harvest, around a hot surface.
6. Wheel fires can be caused by seized brakes, failed bearings, or underinflated tyres causing friction and heat. Often wheel fires ignite after a vehicle stops, as the airflow (which provides cooling) ceases.
7. Electrical malfunction, including electrical short circuits, high resistance joints, or heavily loaded circuits, causing ignition of electrical wiring insulation.
8. Aftermarket accessory failure, typically due to poor quality components or unqualified component installation.