Ignition Source in Class I, Division 1 Locations

A Class I, Division 1 location is defined in Sec. 500.5(B)(1)(1) of the 2011 NEC.

May 20, 2014

Class I, Division 1 locations are those in which ignitible concentrations of _____ can exist under normal operating conditions.

a) combustible dust
b) easily ignitible fibers or flyings
c) flammable gases or flammable liquid produced vapors
d) pyrotechnics

See answer and applicable Code reference

The correct answer is: c) flammable gases or flammable liquid produced vapors

Article 500 outlines the requirements for hazardous (classified) locations, Classes I, II, and III, Divisions 1 and 2. A Class I, Division 1 location is defined in Sec. 500.5(B)(1)(1). More specifically, it notes that a Class I, Division 1 location is a location "in which ignitible concentrations of flammable gases, flammable liquid-produced vapors, or combustible liquid-produced vapors can exist under normal operating conditions."