Quick megger question

[mark32]

Hi there,

Just wanted to know how one chooses a test voltage when using a megger. I've heard to test at double the circuit voltage, thus, test at 250v for a 125v circuit, is this true? Another question just came up, let's say you are testing a 240v circuit. If you test line to ground would you still use 250v and use 500v to test line to line? Thanks

 

[zog]

The test voltage is based on the voltage rating of the equipment, the operating voltage is ignored, so phase to phase and phase to ground test voltages are the same.

See attachment, NETA ATS table 100.1

Also, dont forget to tempature correct your readings, makes a huge difference in a cold or hot environment.