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Outstandng 18th Oddities

AJJewsbury
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.
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  • 0
    My comments while not directly related to BS7671 were my attempt to explain how I believe we have got from the 224 pages of A5 of the 14th edition to 560 pages of A4 of the 18th. Nearly 5 times the content. Are we 5 times as safe as a result or if the 14th were updated with RCDs, metal consumer units, AFDDs, changes to values and bonding etc would we be actually safer as more people would be able to understand and follow the standard? I make no claims that the 14th was an excellent example but to me it was reasonable understandable. One lesson I have learnt over many years is that it is very difficult to make things simple, perhaps we should all be trying harder?


    My example of the surgeon was an attempt to show how process and targets can override many years of experience, qualifications, CPD, annual assessments etc to put the patient/user at risk. Having a general anaesthetic alone carries a 1:100,000 risk of death irrespective of the risks associated with a particular operation.  


    How many of us curse while going through the tick box exercise of and EICR deciding for each box if it is a tick, C1, C2, C3, FI, N/V, Lim or N/A and how many of us have got one or more wrong and does it make any dfifference to our conclusion and recommendation. Does anyone ever look t the tick boxes? 


    Have a good week ?
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  • 0
    My comments while not directly related to BS7671 were my attempt to explain how I believe we have got from the 224 pages of A5 of the 14th edition to 560 pages of A4 of the 18th. Nearly 5 times the content. Are we 5 times as safe as a result or if the 14th were updated with RCDs, metal consumer units, AFDDs, changes to values and bonding etc would we be actually safer as more people would be able to understand and follow the standard? I make no claims that the 14th was an excellent example but to me it was reasonable understandable. One lesson I have learnt over many years is that it is very difficult to make things simple, perhaps we should all be trying harder?


    My example of the surgeon was an attempt to show how process and targets can override many years of experience, qualifications, CPD, annual assessments etc to put the patient/user at risk. Having a general anaesthetic alone carries a 1:100,000 risk of death irrespective of the risks associated with a particular operation.  


    How many of us curse while going through the tick box exercise of and EICR deciding for each box if it is a tick, C1, C2, C3, FI, N/V, Lim or N/A and how many of us have got one or more wrong and does it make any dfifference to our conclusion and recommendation. Does anyone ever look t the tick boxes? 


    Have a good week ?
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