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BS7671;2018 Minor works certificates.

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


What do you actually think of them?


Andy B.
  • Yes, in what has become the tradition, 18th Edition forms are available here: https://electrical.theiet.org/bs-7671/model-forms/


    Have you got to the bottom of which trip time (longest @ IΔn or longest @ 5IΔn) is required to be entered into the RCD disconnection time in Part 4 of the Minor Works (or field 22 of the Generic Schedule of Test Results)?
  • I've confused myself.


    The Minor works Certificates in the link above are the BS7671:2008 version.


    I thought that we were going to be expected to use the draft version of BS7671:2018, but that version didn't make it into the final version of BS7671:2018.


    So the new version requires more information, but not as much as I was expecting from having looked at the draft version, which wanted additional information including Zdb and the name of the manufacturer of the circuit protective device which would have highlighted the installation of devices that were not original consumer unit equipment manufacturers devices.


    Andy B.

  • Andrew Betteridge:

    I've confused myself.


    The Minor works Certificates in the link above are the BS7671:2008 version.


    I thought that we were going to be expected to use the draft version of BS7671:2018, but that version didn't make it into the final version of BS7671:2018.


    So the new version requires more information, but not as much as I was expecting from having looked at the draft version, which wanted additional information including Zdb and the name of the manufacturer of the circuit protective device which would have highlighted the installation of devices that were not original consumer unit equipment manufacturers devices.


    Andy B.




    Andy,


    If you look on the right hand side of the page, there's a download link for the 2018 versions of the forms ... in the big green panel with the picture above ... I know that download link works as I've used it myself.

  • Former Community Member
    0 Former Community Member
    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?

  • 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?
  • 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.

  • 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.
  • 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........
  • 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.
  • 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.