UFC 3-535-01
17 November 2005
14-4.2.3
The cables should not directly cross each other and must be separated by
the specified distance.
14-4.2.4
Screened material should be placed under and over the cables, and rocks
or pebbles should not contact the cables.
14-4.2.5
The cables are not to be bent sharply where they enter (or leave) a
conduit, and should be supported properly by tamped ground so future settling will not
cause sharp bends.
14-5
CABLE ELECTRICAL TESTS
Test cables directly buried in earth (that is, not in duct or conduit) before and after the
trench is back-filled. Test each underground circuit as follows:
14-5.1
Continuity ohmmeter or equivalent continuity test on each series circuit.
The circuit should then be checked with a megger test set, to make sure it is free of
grounds. Any faults indicated by these tests should be located and repaired before
proceeding with high voltage tests.
14-5.2
High voltage insulation resistance test on each series and multiple
underground circuit to determine complete freedom from grounds. Whenever possible,
these tests must be performed when the ground is thoroughly wet because circuit wiring
that passes insulation resistance tests during dry weather may fail after a heavy rain.
14-5.2.1
The test procedure follows for each circuit:
14-5.2.1.1 Disconnect both leads from the regulator output terminals. Support both
leads so there are air gaps of several inches between bare conductors and ground.
Make sure the cable sheath is clean and dry for a distance of at least 300 millimeters (1
foot) from the end of the cable. Also make sure exposed insulation at the end of the
cable is clean and dry.
14-5.2.1.2 Test each circuit immediately after installation according to "First Test on
New Circuit." Test any circuit installed for 60 days or more, even if it has not been
operated, according to "Succeeding Old Circuit." (See Table 14-9.)
14-5.2.1.3 The maximum acceptable leakage current, in microamperes, should not
exceed the values in paragraph 14-5.2.4.
14-5.2.1.4 When additions are made to old circuits, test only the new sections
according to "First Test on New Circuits." Test the complete circuit at the reduced
voltages to ensure reliable operation. See Table 14-9.
14-5.2.1.5 Connect both conductors, and apply the test voltage shown for 10 minutes
between conductors and ground.
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