KS 3-2010
Page 16
6.4.4 Test
NOTE—If the switch is equipped with an under-voltage trip release, energize the trip release to allow proper operation of the switch.
6.4.4.1 The test is performed as follows.
6.4.4.1.1 Apply test current across a pole equal to the switch rating (or 500 Amperes minimum for
switch rated in excess of 500 Amperes). Record the millivolt drop and the test current. Do not maintain
current for more than 1 minute. If this equipment is not available, use the following test.
6.4.4.1.2 Apply test current across a pole of 10 Amperes, or the Ampere rating of the switch, for switch
rated less than 100 Amperes. For switch rated more than 100 Amperes, apply a test current across a
pole of 100 Amperes. Record the millivolt drop and the test current, or resistance. Do not maintain current
for more than 1 minute.
6.4.4.1.3 De-energize the test circuit. Manually operate the switch to the OFF and then ON positions.
6.4.4.1.4 Repeat steps 6.4.4.1.1 and 6.4.4.1.2 for a total of three readings on the pole being tested.
6.4.4.1.5 Repeat steps 6.4.4.1.1 through 6.4.4.1.3 for each of the remaining poles of the switch.
6.4.5 Results
Test results will vary according to the switch ampere rating and manufacturer. The manufacturer should
be consulted to determine the maximum allowable voltage drop. If the average test values of any pole of
the switch exceed the maximum allowable drop, the switch may have reached the end of life and
additional tests may have to be conducted.
NOTE—Inconsistent readings could be the result of oxide films or foreign material on the contact surfaces, depending on the service
history of the switch. If high millivolt or high resistance readings are detected, refer to the manufacturer’s recommendations, and if
necessary, clean and/or lubricate the contact surfaces, then repeat tests in this section. If results are still out of acceptable range,
the switch should not be returned to service.
6.4.6 Reinstall Switch
If applicable, reinstall the switch following manufacturer's instructions. Also refer to 5.4 for information on
reinstalling wire connectors and/or conductors.
6.4.7 Reinstallation Procedure
For reinstallation or replacement of the switch and/or accessories, follow the safety installation
procedures given in 2.3.
© Copyright 2010 by the National Electrical Manufacturers Association.
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