Facilities use Class 1 Division 2 lighting where a fire or explosion hazard may exist due to flammable liquids or gases being used or stored there. The standard UL 844 and the National Electric Code (NEC) article 501 govern the construction of lighting fixtures to provide confidence in the safe operation in hazardous classified environments.
The National Electrical Code (NEC), National Fire Protection Association (NFPA), and Underwriters Laboratories (UL) published a guide along with codes that categorize hazardous areas into classes, divisions, and zones.
Class 1 hazardous locations refer to facilities that deal with flammable gases, vapors, and liquids.
Division 2 indicates that the facility handles, processes, or uses flammable material at the location. However, the material isn’t constantly circulating in high enough concentrations to be ignitable. Simply put, this requires proper handling and storage of flammable gases, vapors, or liquids to prevent ignition under standard operation. Additionally, the facility might utilize a positive-mechanical ventilation system that prevents high concentrations from forming. As a result, the presence of flammable gases or liquid-produced vapors will never reach an ignitable level.
Division 2 has four group subdivisions, defining the different types of hazardous materials present at a location.
The following signify the groups of hazardous substances that may be present at a location.
A – contains only acetylene.
B – includes hydrogen, gases with more than 30% hydrogen by volume, butadiene, ethylene oxide and propylene oxide.
C – includes acetaldehyde, cyclopropane, diethyl ether, and dimethyl hydrazine.
D – includes gasoline, acetone, ammonia, benzene, butane, methane, propane, alcohols and other more commonly encountered compounds.