Which test method to use depends greatly on the age and type of cable system installed. Many of the methods described in this article can be performed as an acceptance or maintenance test, depending on conditions such as the test voltage applied or duration of test.

The objective of any diagnostic test is to identify problems that may exist with a cable- in a non-destructive way - so that preventative measures can be taken to avoid potential failure of that cable when in service. Diagnostic assessments may apply to cable systems comprising of the cable itself and the associated accessories such as splices and terminations.

Methods of Cable Testing:

1. Dielectric Withstand Test

2. Very low frequency (VLF)

3. Damped alternating current (DAC) voltage

4. Power factor / dissipation factor (tan delta)

5. DC Insulation Resistance

6. Partial discharge