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cables with CH pipes

Discussion in 'Electrics UK' started by chappers, 3 Dec 2015.

  1. chappers

    chappers

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    Would it be ok to run two cables for a ring main in with CH pipes as follows.
    Total ring board to board 2.5mm T&E, 36m fixed method 1 within a boxing 200mm x 50mm x2400mm containing 22mm CH flow and return and domestic water 15mm Hot and cold.
    obviously can keep cables adjacent to cold water pipe and CH pipes furthest away.

    Any issues with that?
    Thanks in advance
    Gareth
     
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  3. ban-all-sheds

    ban-all-sheds

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    What will be the maximum temperature inside the boxed-in section?
     
  4. PrenticeBoyofDerry

    PrenticeBoyofDerry

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    Could you go in to a little more detail regarding installation method 1?
     
  5. chappers

    chappers

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    Interesting re the temp, central heating pipes carrying water at 65 degrees, maybe high 40s-50s, that was my primary concern.
    As for method 1, just clipped to the wall inside the boxing. It's probably got some new designation nowadays
     
  6. Iggifer

    Iggifer

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    It's reference method C
     
  7. JohnD

    JohnD

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    climaflex or similar insulation on the pipes will reduce the air temperature inside the enclosure, and also prevent the cables coming into contact with hot pipes.

    lag the pipes first, then measure the temperature. It may affect current capacity of the cable, more so if it is for an immersion heater or electric shower which draws high current for an extended period.

    PVC cables can soften and deform badly if they are pressed against hot pipes (this often happens when they are poked into a notched joist together and a floorboard nailed on top).
     
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  9. PrenticeBoyofDerry

    PrenticeBoyofDerry

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    Clipped direct is reference method C (has been for some time).
    The issue is the build up of heat and that current carrying cable will not be able to dissipate heat satisfactory. So the best thing would be to either, reduce the heat in the enclosed boxing, separate the cables be sectioning off, or increase the cable CSA.
     
  10. chappers

    chappers

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    Thanks for the replies, the current central heating pipes are already in a box following the route and I dangled a temp probe down there over the weekend and it peaked out at 39 degrees.
    I think I will do as above and section the boxing off and insulate around the pipes.
    I realise it's not the deciding factor, but there will only be 4 double sockets on the whole ring as it's for a loft conversion
     
  11. ban-all-sheds

    ban-all-sheds

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    At whatever the CCC is for a cable given its size and installation method etc, the conductor will be at 70°.
     
  12. stillp

    stillp

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    Only at the ambient temperature that was used to determine that CCC - usually IIRC 25 deg Celsius.
     
  13. ban-all-sheds

    ban-all-sheds

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    Ah - "etc" in "given its size and installation method etc" was meant to cover all the derating factors which apply.
     
  14. chappers

    chappers

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    Just to update, separated the central heating pipes from the rest of the boxing with a bit of 2x1 and redid the temperature probe thing. this time it peaked out at 28 degrees, so combined with a bit of insulation around the CH pipes I think I'm happy to go with that.
     
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