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Reference Methods

Former Community Member
Former Community Member
Wondered what installation reference method people might be using for a T&E cable on a masonry wall that is then covered with plasterboard, ie a typical dot and dab affair. I think "C" is correct as all installation methods involving a cable in contact with a wall and NO insulation map to reference method "C". Wouldn't think the plasterboard or covering the cable with capping would make any difference. I raised the question due to seeing A,B, & C on various other contractors certs.
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    Well, that is similar to the 'what is above the ceiling ?'  At some point you have to assume - and we do not care so long as the cable does not overheat, so the end of a lighting circuit supplying half an amp of load need not worry us - asking if it is a configuration that is more like 101 than  it is to  C is utterly moot.

    The only time it matters is if the cable is near it's rated limit, and as long runs are decide by volt drop, and most short runs are to loads that are not continuous , there are not too many cases to consider.

    And if we get it wrong, the cable will run hot instead of warm - PVC is rated for 70C continuous, but if you drop an off cut it into your tea or coffee (or someone else's, depending on your morality and sense of humour) it does not melt like butter, it just gets a bit more flexible. Indeed only around 120C does it start to fail in short order, so there is quite a bit of margin for the odd overload of a few hours. (As power goes as the square of current, about 150% of the rating to get double the temperature rise, and that is quite a bad misjudgement..)

    It's not great, but the sky does not fall immediately

    M.
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  • 0
    Well, that is similar to the 'what is above the ceiling ?'  At some point you have to assume - and we do not care so long as the cable does not overheat, so the end of a lighting circuit supplying half an amp of load need not worry us - asking if it is a configuration that is more like 101 than  it is to  C is utterly moot.

    The only time it matters is if the cable is near it's rated limit, and as long runs are decide by volt drop, and most short runs are to loads that are not continuous , there are not too many cases to consider.

    And if we get it wrong, the cable will run hot instead of warm - PVC is rated for 70C continuous, but if you drop an off cut it into your tea or coffee (or someone else's, depending on your morality and sense of humour) it does not melt like butter, it just gets a bit more flexible. Indeed only around 120C does it start to fail in short order, so there is quite a bit of margin for the odd overload of a few hours. (As power goes as the square of current, about 150% of the rating to get double the temperature rise, and that is quite a bad misjudgement..)

    It's not great, but the sky does not fall immediately

    M.
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