75.7 The measurement circuit for leakage current shall be as shown in Figure 75.1. The measurement
instrument is defined in (a) – (c) and, unless it is being used to measure leakage from one part of the unit
to another, the meter shall be connected between the accessible parts and the grounded supply
conductor. The meter which 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 of
the attributes of the defined instrument.
a) The meter shall have an input impedance of 1500 resistive shunted by a capacitance of
0.15 μF.
b) The meter shall 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 kHz, the measurement circuitry shall have a frequency
response (ratio of indicated to actual value of current) that is equal to the ratio of the impedance
of a 1500 resistor shunted by a 0.15 μF capacitor to 1500 . At an indication of 0.75 mA, the
measurement shall have an error of not more than 5 percent.