was the megger used right

Discussion in 'General Electronics Chat' started by THEELECTRICIAN, Aug 26, 2009.


    Thread Starter New Member

    Aug 26, 2009
    today one of the guys from work disconnected the wires going into a motor turn off the breaker feeding it whitch it was like 100 ft. away.put one of the leads from a megger into the wire where the load was and the other into the frame of the panel once he push the button of megger it showed as bad do you guys think he used the megger correctly to test the insulation of the wire
  2. b.shahvir

    Active Member

    Jan 6, 2009
    From what i understand of your description, he was probably performing insulation test of motor windings w.r.t. Earth. The megger should display at least 2 MΩ for healthy insulation for a motor rated at 415VAC.

    In my opinion, the procedure adopted by that person was appropriate, as during meggering process the other auxilliary or control equipments viz. ckt. breakers, fuses, indicating instruments, etc. have to be electrically isolated or switched off for correct readings as well as for instrument and equipment safety standards.

    Kind regards,
  3. GetDeviceInfo

    Senior Member

    Jun 7, 2009
    Yes, as a preliminary check. Should be followed up by more isolated checks to see if motor or wiring is the fault.
  4. irulu.electrical

    New Member

    Aug 27, 2009
    It's the correct procedure to check the insulation resistance of the outgoing cable which goes to feed the motor.the low value of insulation resistance indicates that the cable insulation might be damaged.