UL 758-2012 pdf download
UL 758-2012 pdf download.Appliance Wiring Material.
32.3 The wrapped wire specimens and the metal mandrels are to be placed in a circulating air oven set at a temperature which is identical to the rated temperature of the wire.
32.4 The dielectric tester shall supply a DC test potential that is continuously variable with an output from zero to at least the test voltage of the wire specimen being tested The output voltage is to be monitored continuously by a voltmeter. The overall accuracy shall not introduce an error greater than five percent. The maximum current output of the tester’s transformer is to be enough for testing samples to dielectric breakdown without tripping of the cwcuit bealcer by the charging unit. The test leads of the dielectric tester are to pass through an opening Into the circulating air oven or In some way be connected to the specimen while it is at the specified temperature in the circulating air oven.
32.5 With the sample and metal mandrel in the oven, one test lead of the dielectric tester is to be connected to the conductor of the test specimen as one electrode arid the other connected to the metal mandrel as the other electrode. The voltage is to be increased from zero to 1.25 times the DC voltage rating of the specimen at a rate not exceeding 500 volts per second. When this level is reached without breakdown, the voltage is to be held constant at this level for a period of seven hours and then returned to zero at the same rate.
32.6 Compliance is determined wl’ien unaged and oven aged specimens withstand the test voltage without breakdown for a period of seven hours.
33 High-Voltage Cut-Through Test, Special Rated TV Wire Only
33.1 Specimens of finished high-voltage DC rated TV use wire are to be tested in accordance with the method described in 33.2 — 33.7. Insulated conductors composed of multiple layers of insulation are to be tested only as a finished cable. Insulated conductors, insulated flat cables or the insulated conductors of a jacketed cable are to be tested. In the case of a jacketed cable, the insulated conductors are to be removed and tested independently of the jaclieted cable.
33 1 revised April 24, 2006
33.2 One specimen of the finished wire at least 12 inches (305 mm) long is to have a weight attached to each end. The weight is to be 1 lbf (4.5 N or 0.45 kgf) for wire sizes 20 AWG or smaller and 2 IbI (8.9 N or 0.91 kgf) for wire sizes 19 AWG or larger. One end of the specimen is to be stripped of insulation so that a dielectric tester test lead is capable of being attached to the specimen’s conductor.
33,3 The center portion of the test specimen is to be hung so that it fits snugly over an upturned U-shaped metal channel. The upturned U-shaped metal channel is to be elevated and supported in a horizontal position by a stand or some other equivalent holding device that enables the weights to hang freely on either side of the channel The upturned edges of the U-shaped channel are to be rounded and have a radius of 0.015 inch (0.38 mm) or have drill rods with a diameter of 0.032 inch (0.8 mm) fastened in place along the upturned edge of the channel. See Figure 33.1.
33.4 The wire specimen with the hanging weights positioned over the upturned U-staped channel is to be placed in a circulating air oven with a temperature the same as the rated temperature of the wire,
33.5 The dielectric tester is to supply a DC test potential that is continuously variable with an output from zero to at least the test voltage of the wire specimen being tested. The output voltage is to be monitored continuously by a voltmeter. The overall accuracy shall not introduce an error greater than five percent. The maximum current output of the tester’s transformer is to be enough for testing samples to dielectric breakdown without tripping of the drcuit b.’eaker by the charging unat. The test leads of the dielectric tester are to pass through an opening into the circulating air oven or in some other way be connected to the specimen while it is at the Specified temperature in the circulating air oven.
