Megger readings

[Bill avoider]

I am planning to Meg a 480 volt 3 phase motor leads to ground using 1000 volts DC. What are acceptable ohm values and when should I be concerned.

 

[Pete999]

I am planning to Meg a 480 volt 3 phase motor leads to ground using 1000 volts DC. What are acceptable ohm values and when should I be concerned.

I take it from your location you are an American, what does you NEC recommend?

 

[Bill avoider]

Pete I am from Quakertown PA . You are in the Lehigh valley? I will check the NEC. I am hearing anything under 500 ohms is trouble.

 

[Pete999]

I take it from your location you are an American, what does you NEC recommend?

Here we test up to and including 500V a DC test voltage of 500V and minimum IR reading of 1.0 Mohm

 

[Bobster]

1Mohm is the minimum here when a motor is tested at 500VDC. Although if you had a result this low, somethings going wrong somewhere and would need investigating.

 

[davesparks]

Pete I am from Quakertown PA . You are in the Lehigh valley? I will check the NEC. I am hearing anything under 500 ohms is trouble.

500ohms on an IR test would be a failure in anyone's book I think!

 

[PEG]

I'm really disappointed,i thought this thread related to some extremely high readings of one sort,or another...still, 0.0005 Mohms,would not be acceptable :lips2:

 

[telectrix]

OP is american. over there everything is mega, so he may have missed the M.