Insulation resistance test dc side

[ElectroW3b]

I am going to do my first install and at the risk of getting shot down, I was told on my training that you can NOT do a insulation resistance test dc side? However since been told by a friend that is wrong! Can someone please tell me the exact sequence, as everyone has a different take on this. I don't wish to name the training provider but I hear the nic do it somewhat different and ask for more results than the others. Hope that is as clear as mud, just want to know how it's done!

 

[yellowvanman]

Page 53 of the DTI Guide to installing PV Systems:

Two Methods:
a) Test between array negative and earth followed by test between Array positive and earth
or
b) Test between earth and short-circuited Array Negative and Positive.

 

[Maff]

Was told on my training course (2399) to test both +ve and -ve to earth an to set the tester to 500v to testand not 1000 as max cable rating is 1000v and your test equiptment could well deliver +/- 5%

 

[dandy]

the supply must be isolated when performing an insulation resistance test is this true or false

 

[yellowvanman]

The ac should be isolated but the dc should be on as you are testing the modules and dc cabling from earth and the metal fixings.