UL 482 Standard For Portable Sun/Heat Lamps

20.3 All exposed conductive surfaces are to be tested for leakage currents. The leakage currents from these surfaces are to be measured to the grounded supply conductor individually as well as collectively where simultaneously accessible and from one surface to another where simultaneously accessible. Parts are considered to be exposed surfaces unless guarded by an enclosure considered acceptable for protection against electric shock as defined in paragraphs 5.5—5.7. Surfaces are considered to be simultaneously accessible when they can be readily contacted by one or both hands of a person at the same time. These measurements do not apply to terminals operating at voltages that do not present a risk of electric shock, such as those supplied from an isolating transformer device operating at a potential not exceeding 30 V rms or 42.4 V peak.

20.4 If a conductive surface other than metal is used for the enclosure or part of the enclosure, the leakage current is to be measured using a metal foil with an area of 10 by 20 centimeters in contact with the surface. Where the surface is less than 10 by 20 centimeters, the metal foil is to be the same size as the surface. The metal foil is not to remain in place long enough to affect the temperature of the sun/heat lamp.

20.5 The measurement circuit for leakage current is to be as shown in Figure 20.1. The ideal measurement instrument is defined in items A— D. The meter that is actually used for a measurement need only indicate the same numerical value for a particular measurement as would the defined instrument. The meter used need not have all the attributes of the defined instrument.

A. The meter is to have an input impedance of 1,500 ohms resistive shunted by a capacitance of 0.15 microfarad.

B. The meter is to indicate 1.11 times the average of the full-wave rectified composite waveform of the voltage across the resistor or current through the resistor.

C. Over a frequency range of 0—100 kHz, the measurement circuitry is to have a frequency response (ratio of indicated to actual value of currents) that is equal to the ratio of the impedance of a 1,500 ohm resistor shunted by a 0.15 microfarad capacitor to 1,500 ohms. At an indication of 0.5 mA, the measurement is to have an error of not more than 5 percent.

D. Unless the meter is being used to measure leakage from one part of a sun/heat lamp to another, the meter is to be connected between the accessible parts and grounded supply conductor.

20.6 A sample of the sun/heat lamp is to be tested for leakage current starting with the as-received condition, but with its grounding conductor if any, open at the attachment plug. The as-received condition being, without prior energization, except as may occur as part of the production-line testing. The supply voltage is to be adjusted to 120 V. The test sequence with reference to the measuring circuit (Figure 20.1) is to be as follows: (See Figure 20.1 on page 86.)

A. With the switch S1 open, the sun/heat lamp is to be connected to the measuring circuit. Leakage current is to be measured using both positions of switch S2, and with the sun/heat lamp switching devices in all their operating positions.