The introduction of cables with extruded dielectric insulation and of modern splicing technology has
imposed new conditions and restrictions on cable fault locating. The use of excessive high voltages and
energies during AC, DC and surge testing of service-aged power cable systems with extruded dielectric
insulation may overstress insulation, creating defects which become faults after the cables are returned to
This guide is intended to be applied to medium voltage distribution cables. Medium voltage distribution
systems generally operate at system voltages above 1kV and up to 34.5 kV nominal.
The end user of the cable circuit should evaluate the necessity for verifying the integrity of extruded
dielectric insulated cables, and, if they are in critical service, proceed to perform the high voltage/energies
testing. If not detected during dielectric tests, defects in dielectric materials may result in cable failures
during the transient voltage surge episodes while in service.