UL 781-2009 pdf download – Portable Electric Lighting Units for Use in Hazardous (Classified) Locations.
7.4 Class I, Zone 1, Group IIC 7.4.1 Explosion-proof electrical equipment intended to be marked in accordance with 40.21 shall comply with all the requirements for explosion-proof electrical equipment for use in both Class I, Group A and Class I, Group B hazardous (classified) locations. CONSTRUCTION 8 General 8.1 Unless constructed as specified in 1 5.2.1 .1 or 1 5.2.2.1 , a portable lighting unit shall have a lamp compartment sealed from a terminal compartment enclosing the provision for connection of a 3-conductor cord. A portable lighting unit shall be of the hand-held type or shall be mounted on a movable base or stand with or without casters or wheels. 9 Lamp Enclosure 9.1 Unless as specified in 9.4 and 9.5, a lamp enclosure, other than a light-transmitting part, shall be made of iron, steel, copper, brass, bronze, aluminum, or an alloy containing not less than 80 percent aluminum. A metal such as zinc, magnesium, or their alloys, shall not be used. 9.2 A cast-metal part shall not be less than 1 /8 inch (3.2 mm) thick. 9.3 A light-transmission section of a lamp enclosure shall be glass. 9.4 A nonmetallic material forming a part of a lamp enclosure shall be sufficiently strong and rigid to resist the abuses likely to be encountered during intended use. 9.5 Among the factors that are to be taken into consideration when determining the acceptability of a nonmetallic material are: a) Mechanical strength; b) Resistance to impact; c) Moisture-absorptive properties; d) Resistance to fungus; e) Combustibility; f) Resistance to repeated explosions; g) Resistance to solvents as covered by the hazardous location group or groups under consideration; h) Resistance to accumulation of electrostatic charges; and i) Resistance to distortion at temperatures to which the enclosure may be subjected under conditions of normal or abnormal use. All of these factors are to be considered with respect to thermal aging.