feeder insulation resistance testing (megging)

[hacim23]

For pre-termination megging of feeders is it enough to simply test color to color, just the wires, and not to a solid ground? Does this still prove the insulation is good? This always comes up on the job but no one seems to know the set procedure for it. Thanks.​

 

[Ingenieur]

no

think about this
one insulated conductor
one with some cuts in the insulation
you would read a hi meg reading but still have a gnd fault on one

but if you meg both to the same ref gnd, and both read good, you know they will be good to each other