Rules and Guidelines
Want to participate in the discussions? Please read our Community Rules and Guidelines. Need some help? Visit Support and Answers.

  • State Not Answered
  • Locked Locked
  • Replies 33 replies
  • Subscribers 30 subscribers
  • Views 6750 views
  • Users 0 members are here
Options
You may also be interested in
This discussion is locked.
You cannot post a reply to this discussion. If you have a question start a new discussion

EICR and IR Testing

Former Community Member
Former Community Member
Oh the bane of IR testing on EICRs

Now its just impracticle to disconnect all loads to carry out IR testing, I think everyone can agree on that. And that Phase and Neutral are connected then tested to earth.


This is what I do, and then test @250V as to avoid damaging any equipment in the installation. And unless the IR value was <.5 Meg, would not bother me. What BS7671 states, but BS7671 is maybe somewhat unclear in that if that voltage (250V) was used then .5meg value should used, but that value should only be used on SELV, and PELV. Now experience also tells me that even if you had a return 0.0, and then did Kohms by using the ohms setting, even values of 100Kohms are fine. (Actually can be much lower than this) and we are pretty clear that its not the cable reurning these values.


So question is when doing an EICR @ 250V, at what point would you recommend an FI? For me the value would have to be <.5Meg
Parents
  • 0
    The old textbooks used to quote the example of uninsulated live parts only being some fraction of a hair's breadth apart - so the test voltage was chosen to be more demanding than normal service to reveal such faults before the 'bang test' did - the worry being that lower test voltages may not arc across small gaps and so give false pass results.


    Given that 230V nominal can be anything up to 253V and being a.c. those are r.m.s. values, the peak voltage in normal service is going to be something like √2 higher - say about 360V - a 250V d.c. test alone perhaps isn't that reassuring.


    Personally I do a 250V test first - just in case there's something still connected that shouldn't be (which usually isn't an issue with L+N - PE tests) - and if that shows reasonably clear, then try the proper 500V test.


      - Andy.
Reply
  • 0
    The old textbooks used to quote the example of uninsulated live parts only being some fraction of a hair's breadth apart - so the test voltage was chosen to be more demanding than normal service to reveal such faults before the 'bang test' did - the worry being that lower test voltages may not arc across small gaps and so give false pass results.


    Given that 230V nominal can be anything up to 253V and being a.c. those are r.m.s. values, the peak voltage in normal service is going to be something like √2 higher - say about 360V - a 250V d.c. test alone perhaps isn't that reassuring.


    Personally I do a 250V test first - just in case there's something still connected that shouldn't be (which usually isn't an issue with L+N - PE tests) - and if that shows reasonably clear, then try the proper 500V test.


      - Andy.
Children
No Data

Join us to get the best from IET EngX.

Joining EngX lets you personalise your experience so you stay up to date on the topics that interest you, plus you’ll be able to make connections who are looking to collaborate, exchange ideas and more.

Join us Not now

Community Rules & Guidelines