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32.2 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
if simultaneously accessible, and from one surface to another if simultaneously accessible. Parts are
considered to be exposed surfaces unless protected against electric shock as defined in 8.1.2. Surfaces
are considered to be simultaneously accessible if they can be readily contacted by one or both hands of
a person at the same time. These measurements do not apply to output terminals operating at voltages
less than 30 volts rms (42.4 volts peak). If all accessible surfaces are bonded together and connected to
the grounding conductor of the power-supply cord, the leakage current may be measured between the
grounding conductor and the grounded supply conductor.
32.3 If a conductive surface other than metal is used for the enclosure or a 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. If 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 converter.
32.4 The circuit for the leakage current measurement is to be as illustrated in Figure 32.1. The
measurement instrument is defined in (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 1500 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 voltage across the resistor or current through the resistor.
c) Over a frequency range of 0 – 100 kilohertz, the measurement circuit is to have a frequency
response – ratio of indicated to actual value of current – that is equal to the ratio of the impedance
of a 1500-ohm resistor shunted by a 0.15-microfarad capacitor to 1500 ohms. At an indication of
0.75 milliampere, the measurement is to have an error of not more than 5 percent at 60 hertz.
d) Unless the meter is being used to measure leakage from one part of a converter or inverter to
another, the meter is to be connected between an accessible part and the grounded supply
conductor.
32.4 effective April 13, 1993
DECEMBER 14, 1993UL 45846
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