Grounding cables not under test

[epenland]

When testing A-phase of a three-phase cable, B and C Phases are grounded because:

Any ideas, all i know is that "It may induce a high voltage into them" is not the right answer

[gchoquette]

Any ideas, all i know is that "It may induce a high voltage into them" is not the right answer

By grounding the other two, you will immediately find out if there is a phase-phase short. Specifically, it will allow you to see if phase A is shorted to phase B or phase C.