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19mm/20mm Electrical trunking in grey

Discussion in 'Electrics UK' started by Possom, 13 Sep 2019.

  1. JohnW2

    JohnW2

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    Well, if a bundle of 8 once was 100 feet total, then you don't need to guess - each length would obviously have been exactly 12.5 feet.

    However, as I said, 12.5 feet is just over 3.807 metres - so when the 'standard length' of 3.75m arise?

    Kind Regards, John
     
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  2. JohnW2

    JohnW2

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    About 7mm too short for 12.5 feet lengths :)

    Kind Regards, John
     
  3. 333rocky333

    333rocky333

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    I suppose when they started selling in metric they rounded it to 3.75 to make a bundle 30 metres
    Traditionally for lighting, conduit boxes were 2 foot centres, this later became 600mm centres, 609 mm is a bit awkward, so things sometimes alter for convenience, this led to most fittings having fixing slots as opposed to holes
     
  4. JohnW2

    JohnW2

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    I don't really see why the total length in a 'bundle' is (or was) a relevant consideration.

    In mathematical terms, it would seem much more logical to round 3.807 to 3.8 than to 3.75 !

    Kind Regards, John
     
  5. 333rocky333

    333rocky333

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    Whole numbers. quarters etc are surely easier to work with, 3metre plastic pipe comes in bundles of 30, so again a round 90 metres.
    Conduit installs use a lot, so I would say the total bundle length is relevant, for ease of ordering quantities and estimating.
     
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  6. JohnW2

    JohnW2

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    Whole numbers are obviously 'easier to work with' than any sort of fractions, but I'm not really sure about quarters, particularly when expressed as decimals - which can you do quicker/easier 'in your head' - "half of 3.8" or "half of 3.75"?
    Total bundle length is obviously relevant, and I never intended to suggest otherwise. What I meant (in response to your comment, and despite what I actually wrote!) was that whether or not the total bundle length is a 'round number' is irrelevant.

    Kind Regards, John
     
  7. SUNRAY

    SUNRAY

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    I recall that steel tube and trunking was originally 4yds in bundles of 12 tied up with string. When plastic was introduced it was called 13ft but I suspect it was really 4m and in bundles of 10.
    My car took 12ft with ease but not 4m so plastic tube would get bent into place, my van took 4m ok so it almost became a rule that the car was not used for plastic
     
  8. JohnW2

    JohnW2

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    That does sound a little more probable than the 12.5 feet lengths that have been suggested.
    You must have had a pretty long car - around 8 ft has always been about the longest I can get in my cars!

    Kind Regards, John
     
  9. SUNRAY

    SUNRAY

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    Cortina eastate MK4, back seats down. 12ft went from passenger foot well to tailgate with a couple of inches spare as long as it was flat on the boot floor but I would really struggle to get in a 4x4 trunking due to the curve of the floor and front seat height. With care I could fit in 8 10ft scaff poles before the gap between driver and passenger seats stopped any more.

    I carried loads of 8ft melamine boards resting on top of the seats and dashboard with ample length to spare, the problem was stopping them slide backwards and dropping off the dash
     
    Last edited: 14 Oct 2019
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  10. SUNRAY

    SUNRAY

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    Have you considered plastic water pipe? it is available in all sizes including to fit pvc conduit.
    An example:
    https://www.wolseley.co.uk/product/durapipe-abs-airline-pipe-25mm-x-5mtrs/

    I warn it is not cheap but is far more stable than PVC conduit.
     
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