UL 943:2005 pdf download – Ground-Fault Circuit- Interrupters.
33B.3 Limited current abnormal overvoltage test
33B.3. 1 After being tested as described in this section. a ground-fault circuit-interrupter shall comply with the requirements in 33B.1 .1. Each of four previously untested representative GFCIs for each combination of conductor pairs is to be connected to an ac power supply havmg an open circuit voltage equal to the test voltage specified in Table 33B.2.1. The power supply is to incorporate a senes variable resistor that can be adjusted to obtain the shoct-cwcuit current (Isc) specified below. See Figure 33B.3.1. No load is to be connected. The vanable resistor Is to be adjusted such that lsc equals 5 A for the first representative device, 2.5 A for the second. 0.5 A for the third, and 0.125 A for the fourth. The four representative devices are to be energized for 7 hours, or until current to. or temperatures within the GFCI attain equilibrium, or until the GFCI becomes disconnected from the ac supply (due, for example, to open circuiting of a thermal or overcurrent protective device). See Figure 338.3.1.
Exception No. 1: ThIs test Is not required for an end-product employing a component or components that have been previously tested and show,, not to conduct current nor to exhibit any condition in 338,1.6 when subjected to the maximum phase voltage or twice the conductor pair voltage rating as specified i Table 338.2.1 for the end-product.
Exception No. 2: When this test is performed at a current level specified above and results i neither
a) Any condition specified in 338.1.6; nor
bJ Operation of any overcurrent or thermal device
then the test results are also representative of testing of the device at lower current levels.
338.3.2 Permanently-connected receptacle and other type GFCIs intended for mounting in boxes are to be mounted in the smallest standard non-metallic box with faceplate in accordance with the National Electrical Code, ANSIINFPA 70.
34 Extra-Low-Resistance Ground Faults Test
34.1 A ground-fault circuit-interrupter shall withstand extra-low-resistance ground faults.
34.2 In order to determine compliance with the prov,sbons of 34.1, the supply circuit is to have an open-circuit voltage in the range of 100 — 105 percent of the rating of the ground-fault circuit-interrupter. The Impedance of the supply is to be such as to provide a prospective current (the current that would result from short-circuiting the supply terminals) shown in 34.3 or 34,4.
3.4.3 In testing a permanently connected ground-fault circuit-interrupter, the prospective current Is to be 5000 A and the power factor is to be within the range of 0.45 — 0.50.
Exception: In testing a receptacle type ground-fault circuit-interrupter, the prospective current is to be 2000 A and the power factor is to be within the range of 0.90 – 1.0.
34 3 rvised Decanter 16. 1994
34.4 In testing a cord-connected ground-fault circuit-interrupter, the prospective current is to be 2000 A and the power factor is to be within the range of 0.9 — 1.0.
34.5 Each line terminal of a ground-fault circuit-interrupter is to be connected to the supply mentioned m
34,2 using 4 ft (1.2 m) of insulated wire, both selected In accordance with Table 34.1, A fuse is to be connected in series with the ungrounded line conductor. An identical conductor is to be connected between a load terminal and a line terminal of the device so as to represent a ground fault. The device is to be in any position considered to be normal in service. A 1-A fuse is to be connected beween the supply terminal representing the grounded circuit conductor and accessible conductive parts of the ground-fault circuit-interrupter. Surgical cotton is to cover openings of the ground-fault circuit-interrupter where flame may be emitted. See FIgure 34.1.