Fire Cause: Overheated Electrical Outlet Boxes?

Journal Article Title: Fire Cause: Overheated Electrical Outlet Boxes?
Article Author(s): DIXON, HARRY S., PH.D., P.E.
Volume: 5
Volume #: 2
Month: December
Year: 1988

Abstract:

When installed with the long axis vertically two receptacle outlet boxes may have approximately six times the heating per inch width as supply conductors per inch length. Unbalanced design with fire danger under overload or fault exists as regards internal box heating and temperature rise. The required National Electrical Code six inch free conductor length is a contributing cause. This also applies to fires from overhead fixture boxes. In time pyrolysis phenomena can cause fires at such boxes. Recommendations are made as to what should be done to alleviate this unbalanced design and dangerous situation.