While operating his vehicle, the insured smelled smoke, stopped the vehicle and opened
the hood to assess the situation. He noticed a glowing wire generating smoke.
Suddenly, a fire developed in the instrument panel of the occupant compartment,
causing a total loss of the vehicle.
Figure 1 is a view of the occupant compartment near the origin of the fire. The
most severely damaged area was at the instrument panel in the vicinity of a stereo
Since the insured observed a glowing
wire in the engine compartment, the wiring in that area was inspected. A power
wire was found attached to a battery post
as shown in Figure 2. The wire insulation
was badly burned, consistent with excessive current flow, which could cause a
fire. The battery was in good condition.
The arrow in Figure 3 shows the burned
wire routed through the bulkhead at an
air conditioner tube penetration. The
wire is badly burned, but the engine compartment was undamaged, meaning that
a failure in the occupant compartment
caused the excessive current and not any
failure in the engine compartment.
Tracing the wire through the firewall re-
sulted in the discovery of the melted end
(as shown in Figure 4) near a stereo sys-
tem, mounted under the instrument panel.
The melted conductor strands at the end of
the wire as indicated by the arrow were ev-
idence of an electrical fault (short circuit).
This wire was routed in an area where
chaffing of the protective wire insulation
was likely causing a short circuit, melting
of the conductor and ignition of material
in the instrument panel near the stereo.
It is apparent that the installation of
the stereo system was not performed in
a professional manner. The connection to
the battery using the battery clamp is not
proper. A wire termination should be used
and connected to an auxiliary terminal in
the fuse block of the vehicle if possible.
Figure 5 is a view of a typical fuse/re-
lay block in a vehicle. Many of these fuse
blocks have unused terminals explicitly
for the installation of aftermarket electri-
It is also good practice to use a fuse or
resettable breaker in the power wire circuit
to provide protection in case a fault occurs.
Finally, the routing of the wire over a sharp
metal structural member is improper,
since it often results in wire chaffing and
an electrical fault. This particular installation is deficient, suggesting that the installer is a possible target of subrogation.
Charles C. Roberts, Jr., Ph.D., P.E.,
( email@example.com) is president of C.
Roberts Consulting Engineers, Inc.,
which provides professional engineering
services in accident reconstruction,
failure analysis, fire causation, explosion
analysis, and biomechanics.