UL 496:2017 pdf free download – STANDARD FOR SAFETY Lampholders.
4.2.2.2 Flammability
4.2.2.2.1 A thermoplastic (polymeric) insulating matenal used to enclose electrical parts or used to provide direct or indirect support of live parts shall be classed either V-2, V-i, V-0, 5VA, or 5VB, by the burning tests described in UL 94 and CAN/CSA-C22.2 No. 0.17. Outlet-box mounted ceiling lampholders shall be rated 5VA.
4.2.2.3 Electrical properties
4.2.2.3.1 A thermoplastic (polymeric) insulating material used to enclose electrical parts or used to provide direct or indirect support of live parts for outdoor applications shall have a minimum comparative tracking index (CTI) of 175 as determined in accordance with the methods described in UL 746A, UL 746B, and CANICSA-C22.2 No. 0.17.
4.2.2.4 Thermal index
4.2.2.4.1 A thermoplastic insulating material used to enclose electrical parts or used to provide direct or indirect support of live parts shall possess a minimum relative thermal index (RTI) determined in accordance with the methods described in UL 746B and CAN/CSA-C22.2 No. 0.17, as follows:
a) 150 °C (302 °F) for a screw-type lampholder;
b) 90 °C (194 °F) for a fluorescent-type lampholder; or
c) 90 °C (194 °F) for an incandescent pilot type lampholder or indicator type light.
Note: A minimum RTI is not required for a pilot type lamphoider or Indicator type light intended for use with neon or LED light sources.
4.2.2.4.2 Lampholders marked with a temperature rating in accordance with Clause 7.5 shall possess a minimum relative thermal index (RTI) of at least their marked rating.
4.3 Sealing Compound
4.3.1 The depth or thickness of sealing compound over a live nut, screw head, or rivet shall not be less than 1.6 mm (1/16 in). If the underside of the base is not recessed and if in some cases it will be in contact with the surface upon which the lampholder is mounted, the depth or thickness of the sealing compound shall not be less than 3.2 mm (1/8 in).
4.3.2 Sealing compound shall be insulating and shall not soften at a temperature of 100 °C (212 °F). Compliance shall be determined by the sealing compound softening test specified in Clause 5.2.2.
4.3.3 Sulfur shall not be acceptable as a sealant.
4.4 Mounting
4.4.1 Bracket
4.4.1.1 A mounting bracket for a bayonet or screw lampholder shall be attached to the lampholder such that it cannot rotate during installation or removal of a lamp. A single rivet or screw shall not be considered to prevent rotation unless additional means such as projections, keys, or the like are provided to restrict movement.
Note: A lamp connector need not be prevented from turning during installation or removal of a lamp.
4.4.1.2 A mounting hole tapped to receive a screw shall be acceptable if it contains no fewer than two threads for the screw if in metal, or no fewer than five threads if in insulating material. Spring clips, clamps, or other means that provide equivalent support and restriction of rotation may also be used.
4.4.2 Cord pendant
4.4.2.1 The cap of a pendant-type lampholder shall have provision for strain relief such that a pull exerted on the flexible cord is not transmitted directly to the wiring terminals. If a knot is provided for strain-relief, all surfaces of the cap that a knot can touch shall be smooth and well insulated.
4.4.2.2 Hard fiber shall be acceptable as the insulating material employed if the bushing is not less than 1.2 mm (3/64 in) thick and if it is formed and secured in place such that it cannot be affected by conditions of ordinary moisture.