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Ideal loft cable routing

Discussion in 'Electrics UK' started by syne, 25 Jan 2017.

  1. syne

    syne

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    I've looked on the search and around the web but can't get much of a conclusive answer.
    When installing a ring final in a loft is there an ideal/best route for the cable run?

    should it be all under the floor and rise to each socket?
    Run round the rear side of the dwarf walls in a literal ring, clipped to the back of the purlin, to the stud work, in conduit or not? etc etc

    It's a single ring direct from the cu with no spurs, in a very simple loft conversion in a semidetached, no dormer or bathroom.
    Is there an actual method preferred by electricians?
     
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  3. EFLImpudence

    EFLImpudence

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    It's up to you really as long as it is safe.

    Is it a house or bungalow?

    There isn't much point having a ring for a loft with the presumed height and waste of cable going back down to the CU.
     
  4. Taylortwocities

    Taylortwocities

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    That how I've always done it. Nice and easy, up behind the plasterboard and into the box.
    PS How can a ring be described as 'literal', either its a ring or it is not.
     
  5. penguin16

    penguin16

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    I assume by literally ring he means a circle.
     
  6. syne

    syne

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    It's a house, the reason for a separate ring is, it's a nice straight run down a void to the cu and that has enough spare capacity. It's only a couple of meters further than the point where you'd break into the ring so not too much extra cable wise.

    As for literal ring, well I suppose that's the difference between ring and loop..
    Would you bother with conduit? Or clips to rafters?
     
  7. seasickstevie

    seasickstevie

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    ... perhaps more a 'rectangle' (?)
     
  8. syne

    syne

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    Yes, definitely rectangular.
    Out of curiosity what would you guys charge for this?
    Loft is roughly 7x4m with 8 double sockets straight from cu
    A three way switched light for stairs
    A two way switched for 4 down lights
    No access problems, no insulation in yet just framing and floor.

    Only asking because the bc non competent charge is £225 (then + materials cost)
     
  9. Taylortwocities

    Taylortwocities

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    Clip to rafters.

    Its notifiable work, so you probably will save money by engaging a sparky who is happy to oversee your DIY wiring and do the test, cert and notification.
     
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  11. ban-all-sheds

    ban-all-sheds

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    That sounds like a fair-enough reason to choose to have a separate circuit.

    But does not answer the question "why a ring?".
     
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  12. syne

    syne

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    Do you mean as opposed to a radial circuit?
    I couldn't give a reason, well not one that would satisfy a sparky...

    From what I've gathered, a ring is arguably yet slightly better than a radial because of the two returns, a bit of redundancy is created should a part of the circuit be damaged.. er maybe.

    Is there a worthwhile reason to not have a ring?
     
  13. Taylortwocities

    Taylortwocities

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    With a radial you use half the copper. And it's pointless to have a ring for moderate loads, like your needs.

    The problem with rings is that that a broken conductor can go for decades without being detected.provided the cable doesn't overheat due to too much current.
    With a radial, you'll know there's a problem straight away.

    EDIT:
    And a radial is more European:D
     
  14. EFLImpudence

    EFLImpudence

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    Yes.

    The trouble is that redundancy goes undetected and could lead to overload on the remaining circuit.

    Is there a worthwhile reason to have a ring?

    The only reason today for installing a ring circuit is if the first and last accessory is near the supply.
     
  15. ban-all-sheds

    ban-all-sheds

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    That doesn't fit well with you deciding that it's OK for you to do electrical installation design....


    It's a struggle to come up with many worthwhile reasons to have one.
     
  16. syne

    syne

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    The first/last is near the supply, but that might not be reason enough it seems, likely loading doesn't especially warrant it even if I am a fan of a good ole three bar fire but I do love to feel all intercontinental.
     
  17. ban-all-sheds

    ban-all-sheds

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    How many of them do you plan to use in the loft at the same time?
     
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