Running cable on external wall

Discussion in 'Electricians' Talk' started by Comlec, Mar 6, 2018.

  1. Comlec

    Comlec Screwfix Select

    At a job today that needs a new cooker supply run. The routes through the house are a real pita but both the CU and the cooker point are on the same external wall about 3m apart.
    Not a conventional solution but any reason why this circuit can't be routed on the outside of the external wall in suitable conduit.?
    The circuit is protected by 30ma RCD.
     
  2. JP.

    JP. Screwfix Select

    Very unconventional Mr C - however maybe the only thing which might crop up is bridging of the cavity - worth thinking about? Not for me to say, however I would do it it as long as conduit across the cavity is used (I have used 20mm round sometimes) Lets face facts wall ties bridge cavity as does wall batts and stuff.

    Its either the above or start pulling stuff out the gaff to run cable - huge expense and disruption, wives etc would not be happy to say the least.
     
  3. Coloumb

    Coloumb Screwfix Select

    No problem with that but I would run the cable in placky if bringing a cavity wall. It just won’t look pretty but it is what it is.
     
  4. robertpstubbs

    robertpstubbs Screwfix Select

    I would use flexible conduit through the wall with 3m straight between. I drill the holes oversize and pump mortar or sealant into the gap, which grips the conduit corrugation so it can't move.
     
  5. JP.

    JP. Screwfix Select

    Never tried that Rob, but seems sounds m8
     
  6. retiredsparks

    retiredsparks Super Member

    conduit.jpg No probs...couple of these...25mm plastic tube...lots of room.
    Short spacing on the saddles.
    Sorted.
    Rs
     
  7. unphased

    unphased Screwfix Select

    Perfectly acceptable, Comlec. I prefer black PVC as it looks better on brick. 25mm should be adequate with a 6mm2 T&E inside it. End box top and bottom, bring cable directly through the wall, no need for flexible conduit at all.
     
  8. JP.

    JP. Screwfix Select

    Dont like the idea of bare cable across cavity Un - but hey that's just from a DIY perspective
     
  9. robertpstubbs

    robertpstubbs Screwfix Select

    Where would your cable enter the CU? Would you drill from inside or outside? Could you really do a neat install without using flex conduit?

    Why 25mm for 6mm2 T+E. Why not use 20mm with 6mm2 singles?

    I use black PVC.
     
  10. Comlec

    Comlec Screwfix Select

    I have clear access to drill from either side and bottom access to the CU. Easy job really, thanks for the comments.
     
  11. Pollowick

    Pollowick Screwfix Select

    If ridged/flexible is used across the cavity then if any moisture does get in, it will not reach the other side but drip off inside much te same as it would with wall ties.
     
  12. Bob Rathbone

    Bob Rathbone Screwfix Select

    Slope the conduit in the cavity towards the outside and the back entry end box. If it is full sun, any more than a full length of conduit will need expansion joints or it will snake when it gets warm, or pull out of the boxes when it gets cool. No need for flexible conduit, no need to enter the CCU with conduit if T&E is used. Clean off all the burrs.
     
    Risteard likes this.
  13. unphased

    unphased Screwfix Select

    You wouldn't buy 3 to 4m of 6mm2 singles. Only available in 100m drums. 6mm2 T&E more practical for that reason alone. Not practical to buy short pieces of flex conduit. Nothing wrong with running T&E cable directly across or through a cavity wall, the sheath is good enough to protect it, however, would use conduit if using singles.
     
  14. Lectrician

    Lectrician Screwfix Select

    6mm T+E would fly down some 20mm on a short straight run, but 25mm would help.

    No need for conduit through the cavity. Completely OTT.
     
  15. JP.

    JP. Screwfix Select

    Cant agree with the bit about conduit through cavity Lec and myself always use conduit..the two types being 20mm round and 16mm oval mainly. However saying that the use of the 20mm round is pretty rare, however 16mm is not so (exterior wall lights etc) but I fully appreciate that some people do use it, and some dont, and I would never argue the point.
     
  16. robertpstubbs

    robertpstubbs Screwfix Select

    I suppose it depends on the height of the conduit, the CU, and the cooker switch.

    When I ran conduit outside recently I ran it at 2.6m above ground. It needed to be at least 2.3m up to clear windows and doors. I fitted the conduit in line with a course of bricks and then drilled inwards a few inches from the CU, which is at the same height and exposed on the staircase. Alhough it is not what I actually did, I could have used flexible conduit to go through the wall and bent it round on the inside to line up with a knockout on the CU.
     
  17. robertpstubbs

    robertpstubbs Screwfix Select

    TLC sell 6mm2 single for 59p+VAT per metre.

    I have box full of short pieces of leftover flex conduit.
     
  18. Risteard

    Risteard Screwfix Select

    It's not a choice: non-sheathed singles MUST be installed in containment.
     
    retiredsparks likes this.
  19. Coloumb

    Coloumb Screwfix Select

    What is it with you? All you do is come on this site and pick holes in members semantics. Why don't you help out a bit instead instead criticizing other members? It's not hard is it?
     
  20. Risteard

    Risteard Screwfix Select

    Pointing out that non-sheathed singles must be entirely contained under all circumstances is very helpful of me.

    You're welcome.
     

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