BEAR's experience is that most, if not all electrical failures are mechanical failures. When electrical conductors are examined in a fire scene, the first determination to be made is whether the observed damage is in the suspected area of the fire's origin. The observed damage to the conductors is classified as non-electrical if there is thermal melting, alloying or mechanical damage. NFPA 921 Guidelines elaborate on this.
In a recent case, a Murphy Bed had halogen light mounted above, for reading. The bed caught fire, when it was up. The theories about how the fire started ranged from hot halogen lights left on and igniting bedding, to faulty electrical wiring of the halogen lights. In the end, BEAR engineers were able to demonstrate, that halogen lights, though hot, do not procude enough heat to ignite bedding. The wires to the halogen lights were pinched under the bed, a mechanical failure, that then led to the fire.
BEAR was asked to examined an electric drill, depicted on the left, to determine if it was the cause of a fire in a garage.
The cordless drill was not connected to the power charger at the time of the fire. The charger showed external damage only. BEAR determined that the cordless drill was not the cause of the fire.