Cooksey, Philip. Recessed Lighting, Insulation, and Fire. The International Fire Chief. September, 1980.

Abstract: This article explains how the combination of recessed lighting fixtures and insulation can result in a fire. In 1976, Oklahoma City experienced an unexplained wave of attic fires. The investigation pointed to combustible insulation as the cause. The Assistant Fire Chief Darby lead a further investigation, which discovered that insulation of a fireproof nature was also involved. Darby investigated common heat sources in attics and discovered that recessed light fixture standards were not being enforced. The National Electric Code requires three inches of clearance between thermal insulation and light fixtures.

Darby conducted tests to prove his theory: insulation covering light fixtures was trapping heat generated by the fixtures allowing them to ignite nearby combustibles. The tests proved his hypothesis. An oven effect was created when insulation was placed too close to lighting fixtures. The heat produced could not escape and ignited combustible materials.

One method that did maintain safe temperatures was a five-sided metal box enclosing the light fixture. This box absorbed the heat and allowed it to spread and dissipate. As a result, Oklahoma City enforced new codes concerning insulation in newly constructed attics. All recessed light fixtures must be protected with the five-sided metal box to allow heat to escape. The code changes have resulted in a large reduction in attic fires in the city.

Inside Fire is out of print. For information on obtaining articles from back issues, contact:
National Emergency Training Center
Learning Resource Center
16825 South Seton Ave.
Emmitsburg, MD 21727
Phone: 1-800-638-1821 or (301) 447-1030
Web Site: www.lrc.fema.gov