Most people don’t think about fire risk when installing third-party electronics in their vehicles. But sound systems, two-way radios, and accent lights mean additional wiring, and improperly installed wires can lead to electrical fires hours or days after the initial installation. These fires can ignite the vehicle, the garage where it’s parked, and in some cases, the home to which the garage is attached.

In last month’s column, I discussed the hazards a company generates when it modifies its equipment without both a proper safety evaluation and input from the equipment manufacturer. Likewise, many consumers modify their vehicles or install third-party products that haven’t been properly vetted.

One type of incident I frequently investigate is that of vehicle fires. Over the course of my career I have worked on three vehicle fires caused by lightning strikes, one caused by a dropped cigarette, and one caused by the rod that holds up the hood falling across the battery. Every other vehicle fire I’ve investigated was an electrical fire originating in the vehicle wiring.

Five of the electrical incidents came from the same manufacturing defect. The manufacturer failed to place a grommet in a hole drilled through the vehicle frame. Wires that passed through the hole rubbed on its unfinished edges. Under normal vibration, the wire insulation wore through, and a fire started.

The rest of the electrical fires came about after third-party suppliers improperly modified the electrical system. In most cases, the extra wiring from sound systems, radios, and lights passes through holes drilled in the frame. Missing grommets, along with normal vibrations, led to excessive wear on the wire insulation and caused the fire. A full safety analysis of the third-party electronics could have uncovered this weakness.

Another common vehicle modification is the addition of 6-inch lift kits to four-wheel-drive vehicles. Vehicle manufacturers should expect users of four-wheel-drive-capable, high-ground-clearance vehicles will want to take them off-road. It is also reasonable to expect users will modify the vehicles to improve the off-road experience.

Manufacturers that haven’t designed for or analyzed the safety of this contingency should say the vehicle is not meant for off-road use in their advertising and owner’s literature. If they say nothing, they should expect this reasonably foreseeable use. Yet, at least one manufacturer calls off-roading a misuse of the vehicle when a user makes a warranty claim.

In cases where it is reasonably foreseeable that a user will modify a vehicle, manufacturers should either address such modifications in their owner’s literature, or offer the modifications, like lift kits, as accessories. Such an approach gives the vehicle manufacturer control of the design and installation procedures, which it can subject to a full hazard analysis.

In any case, the manufacturer should not label a reasonably foreseeable and common use as a misuse and refuse to honor its warranty.

Lanny Berke

Lanny Berke is a registered professional engineer and Certified Safety Professional involved in forensic engineering since 1972. Got a question about safety? You can reach Lanny at lannyb@comcast.net.

Edited by Jessica Shapiro