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43.2 In a test to determine whether a switch or other control device complies with the requirements in
43.1, the converter or inverter is to be connected to a supply circuit of rated frequency and maximum test
voltage – see Table 31.1. During the test, exposed dead metal parts of the converter or inverter are to be
connected to the polarity opposite to that of the switching device through a 3-ampere fuse. The device is
to be operated for 50 cycles at a rate of not more than 10 cycles per minute, except that a faster rate may
be employed with the concurrence of those concerned.
43.2 effective April 13, 1993
44 Overcurrent Protection Calibration Test
Section 44 effective April 13, 1993
44.1 A fuse, or a non-adjustable manual reset circuit protective device, provided in the primary of a
transformer for protection of the secondary circuit in accordance with 13.8 shall operate to open the circuit
in not more than the time indicated in Table 44.1 when the transformer is delivering the specified
secondary current.
44.2 To determine if a fuse or circuit protective device complies with the requirement in 44.1, the
transformer is to deliver the test current to a resistance load. During the 2-minute test, the load is to be
adjusted continuously to maintain the required test current. During the 60-minute test, the load is to be
adjusted once after 15 minutes of operation and the test is to be continued without further adjustment.
44.3 If the fuse or circuit protective device is used to protect more than one secondary winding or taps,
each winding or partial winding is to be tested as indicated in 44.1 or 44.2 with the remaining windings
delivering rated load.
Table 44.1
Maximum acceptable time to open
Rated secondary potential, V Secondary test current, A Maximum time for overcurrent
protective device to open, minutes
20 or less 10 2
20 or less 6.75 60
Over 20 200/V max 2
Over 20 135/V max 60
45 Ground-Fault Circuit-Interrupter Evaluation Test For Power Inverters
Section 45 effective April 13, 1993
45.1 The ground-fault circuit-interrupter protection circuit of a power inverter shall remain closed with a
leakage current of 4 mA and shall open with a leakage current of 6 mA when tested in accordance with
45.2.
45.2 To determine if an inverter complies with 45.1, the inverter is to be connected to its rated source of
supply and a variable resistor is to be connected between the ungrounded pole of the line voltage branch
circuit output and the output circuit grounding connection. The resistor is to be adjusted to obtain the
maximum value of leakage current possible without causing the ground-fault circuit-interrupter circuit to
trip, and to obtain the minimum value of leakage current required to cause the ground-fault
circuit-interrupter to trip.
DECEMBER 14, 1993 UL 458 59
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