Insulation Resistance testing

Discussion in 'Electricians' Talk' started by andyspark, Aug 19, 2007.

  1. andyspark

    andyspark Active Member

    If doing a 500V IR test between L & N then obviously you have to be very careful not to fry anything.

    But.... has anyone ever damaged anything by conducting the test between L & N connected and earth. As per Guidance Note 3 this is a valid test when doing a PIR.

    And what about between N and E. Any problems?

    Just curious.
     
  2. X

    X New Member

    As with all insulation tests on an unknown circuit... tis sensible to start with a lower voltage first
     
  3. sinewave

    sinewave Screwfix Select

    Nail it with a 1000V!
     
  4. Squarewave

    Squarewave New Member

    As with all insulation tests on an unknown circuit...
    tis sensible to start with a lower voltage first

    Quite right. If I'm not sure all loads have been removed, I'll start at 250v and see what kind of reading I'm getting.
     
  5. andyspark

    andyspark Active Member

    Yes I accept that starting at 250V is a good idea.

    Do people always do the three tests ie between L & N then L & E then N & E. Or if its a PIR and a pain to disconnect all loads do you consider a test between L and N connected and E sufficient.
     
  6. X

    X New Member

    PME can give an odd result.. if your not aware
     
  7. Squarewave

    Squarewave New Member

    Yes I accept that starting at 250V is a good idea.

    Do people always do the three tests ie between L & N
    then L & E then N & E. Or if its a PIR and a pain to
    disconnect all loads do you consider a test between L
    and N connected and E sufficient.

    I'll do all tests if I know all loads are removed, if not, then the GN3 method of phase and neutral together to earth is acceptable and reasonable, certainly if you've a floor of discharge lamps in a factory, you'll be limited to what you can do, what is reasonable, what access is granted.
     
  8. JP.

    JP. Screwfix Select

    Quick IR Test..

    Isolate power to DB and from the dead side of DB mainswitch do stuff..likewise from dead side of RCD (if splitloader)..all loads and stuff removed if possible (if not isolate circuit which cannot be cleared) and then do the business..on a rewire just do each individual leg..yes?..
     
  9. Squarewave

    Squarewave New Member

    JP, make sure you remove the RCD, or you could damage it even if it is switched off, may still be a connected coil.

    And the rest is basically what we've already discussed, removing loads and what to do if you can't. It isn't always possible to.
     
  10. JP.

    JP. Screwfix Select

    JP, make sure you remove the RCD, or you could damage
    it even if it is switched off, may still be a
    connected coil.

    And the rest is basically what we've already
    discussed, removing loads and what to do if you
    can't. It isn't always possible to.

    All points taken on board Capn Squarewave Sir..;)
     
  11. andyspark

    andyspark Active Member

    Ahh but....yeah but....no but

    No ones answered the question.

    'has anyone ever damaged anything by conducting the test between L & N connected and earth.
    And what about between N and E. Any problems?'

    Anyone.
     
  12. wklivesvtime

    wklivesvtime New Member

    no, how could you damage it without a pd accross it? Thats the point of joining them.
     
  13. Clark Kent

    Clark Kent New Member

    Ahh but....yeah but....no but

    No ones answered the question.

    'has anyone ever damaged anything by conducting the
    test between L & N connected and earth.
    And what about between N and E. Any problems?'

    Anyone.


    Why should you damage anything with L/N together?
     
  14. Clark Kent

    Clark Kent New Member

    As with all insulation tests on an unknown circuit...
    tis sensible to start with a lower voltage first



    Something I do as a matter of caution..



    ;)
     
  15. wklivesvtime

    wklivesvtime New Member

    this is acceptable only for a pir i think. Neww installs all tests, allready energised circuits test to earth only accesable
     
  16. X

    X New Member

    'has anyone ever damaged anything by conducting the
    test between L & N connected and earth.
    And what about between N and E. Any problems?'
    Anyone.

    Ok...

    I haven't
     
  17. andyspark

    andyspark Active Member

    'Why should you damage anything with L/N together? '

    You shouldn't. I'm asking has anyone. You never know.

    BTW wk, I know 'thats the point of joining them.'
    My first post made that clear.
     
  18. andyspark

    andyspark Active Member

    thanks X
     

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