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5
Appendix B:
Heating Cable Testing
5.1
Testing:
A 500 volt insulation tester (Megohmmeter) is used to
check insulation resistance. A minimum value of 20 meg-
ohms should be obtained when testing the insulation resis-
tance between the conductors/tails and the cable sheath,
and between conductors (2-conductor cable only). A digital
multimeter or ohmmeter is used to check the continuity.
To ensure that the joint is waterproof it may be submerged
in water for approximately 24 hours. This treatment will
remove soldering flux from possible pin holes in the braze
and may possibly reveal a moisture leak which might not
otherwise show up for some time. If this is not practical,
a rag soaked in water should be wrapped around the joint
while it is still hot - this procedure is used in the installation
instructions for both the joint and end cap. A decrease in
insulation resistance indicates the presence of pin holes
that must be fixed before proceeding. A final careful visual
inspection of the joint should be made to ensure the work
conforms to the high quality required for this type of
procedure.
Test Equipment
Insulation
Resistance Test:
Continuity Test:
5.2
Insulation Resistance (Megohmmeter) Test –
Test 1
Insulation resistance is measured between the conductors/
tails and the cable sheath, and between conductors. nVent
recommends that insulation resistance testing be con-
ducted at 500 Vdc.
Test Criteria
The minimum insulation resistance for a clean, dry, properly
installed joint is 20 megohms.
48 | nVent.com
500 Vdc Megohmmeter
Standard Digital Multimeter (DMM)
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