meggering 5 kv lines

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stardust

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About to do some insulation resistance testing on 5kv lines (4160v actual) current tester tops out at 1000v. Opinions please - is that high enough voltage or should I get a different tester?
 
Is this a new installation? You should be performing high-potential (dielectric-withstand) testing at a voltage level 2 to 2.5 times the nominal system voltage to ground. If you don't do this sort of thing regularly you can rent a tester or hire the job out if you are unfamiliar with the procedure.
 
jimdavis said:
Is this a new installation? You should be performing high-potential (dielectric-withstand) testing at a voltage level 2 to 2.5 times the nominal system voltage to ground. If you don't do this sort of thing regularly you can rent a tester or hire the job out if you are unfamiliar with the procedure.
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Not a new installation,hasn't been done since 2009 at this facility. last electrician used 1000v megger. I wanted to know if that was good enough or should use 2500v or 5000v. I am familiar with procedure.
 
Even a 5kV Megger test won't tell you much, it is only done on MV cables to be sure it is safe to do an overpotential test. On serviced aged (>5 years) cables none of the current standards (ANSI, NETA, ICEA, IEEE 400, IEEE 576) allow for DC Hipot testing (Considered destructive test). Either an AC Hipot (Short cable run), VLF, PD, or Tan Delta test should be done.
 
Depends on how large your AC Hipot is, the longer the cable the higher the Xc which can make testing at 60hZ hard. We typically use VLF, at 0.1Hz it take 600 times less power to test than it does at 60Hz.
 
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