UL 496:2000 pdf download – Edison-Base Lampholders.
273.2 The switching mechanism of a medium-base lampholder for double-filament lamps and the switching mechanism of any mogul-base lampholder is to be tested with a tungsten-tilarnent lamp load or the equivalent. according to the method described in the Standard for General-Use Snap Switches, UL 20. except that, in the case of a lampholder for doub4e-filament lamps, the load is necessarily to be divided into two sections — one representing each filament of the lamp. Following the usual cycle of high-medium-low-off, this means that the ‘lOw” load actually is to be turned on and off twice during eaci’ complete cycle.
27.3.3 The endurance test with tungsten-filament lamps, indicated in 27.3.2, is the only endurance test — that is, it Is not in addition to the regular endurance test conducted with carton-filament lamps.
28 InsulatIng Links Tests
28.1 Mechanical strength
28.1.1 An insulating link shall withstand for a period of 1 minute a direct pull of 40 lbf applied between the chain attachments at either end; except that, in the case of a factory-assembled link that is not detachable from the chain, the link shall not break before the chain breaks when the complete assembly is subjected to a crec1 pull of not more than 40 lbf (178 N) between the chains at either end.
28.12 Equipment for the mechanical-strength test is to consist of a pair of special connectors for attachment of the two ends of an insulating link. Each connector is to consist of a 0.1 56-inch (3.96-mm) diameter steel rod with one end formed into a hook (for convenience in attaching it to a testing machine) arid the other end machined to prnvide a sphere 0128 inch (3.25 mm) in diameter (approximately the same as the ball section of the conventional chain). The steel between the sphere and the rod proper is to have a rectangular, 0.03 by 0.065 inch (0.76 by 1.65 mm). cross section — the smaller dimension corresponding to the diameter of the dumbbell section of the chain. A connector is to be attached to each end of an insulating link, the assembly connected in a testing machine, and the load applied slowly and gradually until the force is 40 lbf (178 N). The load is then to be held constant for 1 minute or until failure occurs.
28.2 Dielectric voltage-withstand test
28.21 An insulating link shall withstand without beakdown for a period of 1 minute the application of a
60-Hz essentially sinusddal potential of 1500 V between metal chains attached to both ends, after the link has been exposed to a saturated moist atmosphere for a period of 4.8 hours as described In 28.22.
28.2.2 Prior to testing, the insulating links are to be conditioned by exposure for 48 hours in a saturated moist atmosphere at a temperature of 32.0 ±2.00C (89.6 i3.6F). The samples are to be suspended over water in a small, flat-bottomed vessel wtth a tight-fitting cover — the water to be about 1/2 inch (12.7 mm) deep and the samples to dear the water by 1 inch (25.4 mm) or more. The closed vessel containing the water and the suspended samples is to be placed in a controlled-temperature cabinet, with a free circulation of air around the vessel, and the temperature of the air within the cabinet is to be maintained at the value specified.
29 Lining Tests
29.1 Mechanical strength
29.1.1 A lampholder lining shall withstand for 1 minute. without tearing or breaking. a steady pull of 18 lbf (80 N) applied to rods passing through 1/4-inch (6.4-mm) diameter holes punched at diametrically opposite points on the lining and located as shown in Figure 29.1.