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Outstandng 18th Oddities

As far as I recall, we still have some unanswered questions about some of the changes in the 18th. Does anyone have any further information about these? (If not at least this post should ensure the issues aren't forgotten with the demise of the old Forum.)


From memory there was at least:


461.2
  1. The intended meaning of the phrase "neutral conductor is reliably connected to Earth by a low resistance to meet the disconnection times of the protective devices" (given that the Part 2 definition of "Earth" is conductive mass of the Earth rather than any protective conductor or MET; and which protective devices are we talking about anyway?)

  • Also "protective equipotential bonding is installed" - is this intended to mean it actually is installed, or is installed where it is required? (Otherwise new installations with plastic pipes would need N isolation everywhere)


531.3.6 - if it the intention to prohibit the use of Socket RCDs and similar (e.g. FCU RCDs) for additional protection? (being that the generally comply with BS 7288 etc which appears to have a slightly different set of technical requirements to the standards listed)


537.3.2 - Switching off for mechanical maintenance. Although the definition of mechanical maintenance remains unchanged - so continues to include simple relamping - the requirements have changed considerably to the point they just about require complete electrical isolation. Thus a common lightswitch is no longer suitable for switching off for replacing a domestic lamp. Was this really the intention? Or are the changes aimed more at rotating machinery? Given that most householders would prefer not to plunge and entire floor let alone the complete installation into darkness to replace a simple lamp, should we be installing switches rated for isolation in every room?


any others?


   - Andy.
Parents
  • Agree.

    Remember the near-disastrous inclusion of a requirement to install an earth electrode next to the consumer unit, or as near as is practically possible? Good luck with doing that on a 5th floor flat!

    I wonder which numpty thought that one up?

    Probably someone busy serving an industry which is not about turning out quality tradesmen but feeding a voracious appetite for qualifications. Qualifications demanded by an ever burgeoning bureaucracy which – like Parliament – prefers credentials over competence. And still our British trainees are regularly overlooked in favour of incomers who push wages even lower.

    Then we get to buck-passing or the pc term 'Risk Transfer', a most insidious practice if ever there was one.

    This is all about heaping the dung on the little man at the end of the chain.

    Take Cmin for example. If I understand it correctly, the new reduced earth fault loop values were introduced to take into account the potential shortcomings of the supply network. Why should we have to do this? Why can't the supply authorities be made to spend on upgrading their networks instead?

    Next, we have all metal consumer units. A cynic might unhelpfully suggest that thinking was influenced financially on that one. Why not just specify metal consumer units for under-stairs supply intake positions only? Oh! There's no money in that.

    RCD protection everything? Sure, if RCBOs were only a fiver a pop, but then again, there's no money in that.


    Now we have SPDs/AFDs.

    Despite not living in a country which suffers regularly from tropical thunderstorms and the like, we are now expected to fit some costly gizmo of dubious useful value.

    Again, we are expected to address the shortcomings of others, namely poor and less than robust circuit design in the end-product, that big fat flatscreen telly for example.

    Why, instead being made to compensate for the shortcomings of the appliance makers, can we not turn this back to them instead?

    A Wylex AFD thing on screwfix is over a hundred quid! The component material value contained inside is most likely a few pence-worth at most. In fact, I'll bet that the sticky labels and the carton it comes in costs more than the internal workings of the device.

    Me? I'll stick to a good quality 4 way extension bar fitted with anti-surge protection from RS components instead. It's much cheaper.


Reply
  • Agree.

    Remember the near-disastrous inclusion of a requirement to install an earth electrode next to the consumer unit, or as near as is practically possible? Good luck with doing that on a 5th floor flat!

    I wonder which numpty thought that one up?

    Probably someone busy serving an industry which is not about turning out quality tradesmen but feeding a voracious appetite for qualifications. Qualifications demanded by an ever burgeoning bureaucracy which – like Parliament – prefers credentials over competence. And still our British trainees are regularly overlooked in favour of incomers who push wages even lower.

    Then we get to buck-passing or the pc term 'Risk Transfer', a most insidious practice if ever there was one.

    This is all about heaping the dung on the little man at the end of the chain.

    Take Cmin for example. If I understand it correctly, the new reduced earth fault loop values were introduced to take into account the potential shortcomings of the supply network. Why should we have to do this? Why can't the supply authorities be made to spend on upgrading their networks instead?

    Next, we have all metal consumer units. A cynic might unhelpfully suggest that thinking was influenced financially on that one. Why not just specify metal consumer units for under-stairs supply intake positions only? Oh! There's no money in that.

    RCD protection everything? Sure, if RCBOs were only a fiver a pop, but then again, there's no money in that.


    Now we have SPDs/AFDs.

    Despite not living in a country which suffers regularly from tropical thunderstorms and the like, we are now expected to fit some costly gizmo of dubious useful value.

    Again, we are expected to address the shortcomings of others, namely poor and less than robust circuit design in the end-product, that big fat flatscreen telly for example.

    Why, instead being made to compensate for the shortcomings of the appliance makers, can we not turn this back to them instead?

    A Wylex AFD thing on screwfix is over a hundred quid! The component material value contained inside is most likely a few pence-worth at most. In fact, I'll bet that the sticky labels and the carton it comes in costs more than the internal workings of the device.

    Me? I'll stick to a good quality 4 way extension bar fitted with anti-surge protection from RS components instead. It's much cheaper.


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