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BS7671;2018 Minor works certificates.

Sparkingchip
Are you all organised and have a supply of the new certificates to hand?


What do you actually think of them?


Andy B.
  • 0

    Philip Wood:

    In part 4 of the 'Minor Works Certificate' for RCD's it says you should use 'I∆n' and this should be the longest time it takes for the RCD to operate, or in other words the worst case scenario. 




    Is this in BS 7671, or another publisher's version? If BS 7671, please could you let me know the page?


    Regardless, this makes no sense given the test requirements (particularly, the test for additional protection only specifies the 5x test so why record a result for a different test???)

  • 0
    I can't see a problem with a rubber stamp indicating the new edition as most of the criteria are the same as previous editions.


    Legh
  • Former Community Member
    0 Former Community Member
    I Bought some 2018 MWC forms from niceic before Xmas (no niceic logo on them) and I was a bit concerned that they might not comply now that the 18th. is in force but from what I've read here it seems they're ok to use. As i'm no longer a scheme member I will probably only be using MWC's now!
  • 0
    Well. 1.IΔn would give the worst case for both fault conditions and additional protection even though 5.Δn was quoted for additional protection in the last edition. It now appears to be left open.


    Legh


  • Former Community Member
    0 Former Community Member
    In part 4 of the 'Minor Works Certificate' for RCD's it says you should use 'I∆n' and this should be the longest time it takes for the RCD to operate, or in other words the worst case scenario. 
  • 0
    Some SPDs are "one shot" ...


    Certainly no recommended "test" - just inspection to see whether they are OK, and insulation resistance test BELOW their threshold value.
  • 0
    I notice that a column for SPDs has been omitted on the schedule of tests, as this type of protection is generally for individual circuit protection (types 2 and 3) and more likely to be available at a reasonable price rather than AFDDs. It could be that SPDs have no obvious method of testing unless we stick a 5kV DC voltage from a Clare tester otherwise mentioned in the 'equipment vulnerable to damage when testing........
  • 0

    Andrew Betteridge:


    There is only one line available to write comments on the existing installation, not enough for places I end up working in!

     



    You can use them as a template to make your own certificates, as far as I know. If you have Office 2010 onwards, they will open up in Microsoft Word (right click, "open wtih", "Microsoft Word") and then you should be able to add in the lines you need.
  • 0
    Yep, tap the green panel rather than the download link.


    There is only one line available to write comments on the existing installation, not enough for places I end up working in!

    Andy B.
  • 0

    Philip Wood:

    For additional protection the worst case scenario should be used, and this would normally be the 1Δn reading. No idea why they have removed the 5Δn column?




    That's interesting ... surely the Note to Regulation 643.8 implies that where RCDs are used for Additional Protection, it's the longest @ 5IΔn which is required ???


    Where RCDs are used for Fault Protection, Regulation 643.7.1 applies. The disconnection times required for final circuits are in Table 41.1, and therefore (from Table 3A), for example:


    • TN system, the disconnection time of 0.4 s might be achieved at IΔn and therefore we can use that

    • TT system, the disconnection time of 0.2 s might not be achieved at IΔn and therefore the disconnection time should to relate to 5IΔn (if, as per the Note to 643.7.1 states, we take into account the operating characteristics of the device per Table 3A in Appendix 3) - that is unless your tester has a 2IΔn setting


    Where the RCD provides both fault protection and additional protection, which is the "worst-case"? Well, a test at 5IΔn would cover both?

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