Investigation of a light fixture fire

Metal-halide lamps produce light by discharging an electric arc through a gaseous mixture of vaporized mercury and metal halides. Metal-halide lamps for use in spaces with lower mounting heights can produce excessive visual glare in the normal, higher field-of-view unless they are equipped with prismatic lenses. Should the bulb fail, high internal operating pressure of the arc tube can launch fragments of arc tube at high velocity in all directions, striking the outer bulb of the lamp with enough force to cause the outer bulb to break. This article reports an investigation of a light fixture fire and reviews a case study of a metal-halide lamp fire. Causal analysis of the metal-halide lamp fire uncovered contributing factors that created the environment in which the incident occurred. Latent organizational conditions that created error-likely situations or weakened defenses were identified and controlled. Effective improvements that reduce the probability or consequence of similar metal-halide lamp fire incidents were implemented.