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Shed power cable in waste pipe?

Discussion in 'Electrics UK' started by diy_dude, 8 Jan 2007.

  1. diy_dude

    diy_dude

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    Since moving in to my house, I had wondered how they got power to the shed which is sited 20m from the house. This weekend I found that there is a 40mm waste pipe buried just below the concrete slab path. In the pipe there is a bit of 2.5mm2 T+E and a couple of nylon pull strings. The entire length of the external cable run is covered by concrete path slabs (2' x 3').

    In the shed there is a power socket and a light. As far as I can see the feed comes from a junction box in the downstairs ring in the house which is connected to the RCD side of the CU. I have not found the junction box yet.

    Am I ok to continue using this power feed?
    Should I look to replacing the cable in the pipe?
    If I make any changes I am aware of Part P. Whold I be OK to use this old pipe for new cable or would I need to dig it deeper?

    Thanks for any advice.
     
  2. Adam_151

    Adam_151

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    1) Its dodgy

    2) I'd put in a new submain from the board and use SWA

    3) I'd also prefer to see it deeper but I'm not sure that there is much of a likelyhood of it being damaged where it is, as if the patio was ever taken up the slabs would be lifted first and it'd be seen (i'll have to consult my brown book on that to see if set depths are given or whether it just calls for likelyhood to of damage by tools to be kept to a minimum)

    4) It'll be a notifiable job
     
  3. diy_dude

    diy_dude

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    I guessed this would be the case

    Do you mean connect the shed feed to an MCD on the RCD side of the CU?

    It would be appreciated if you could find this out. Google has not helped me find the info yet!!

    I knew that was the case.
     
  4. Mosez

    Mosez

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    If its protected by an RCd then its perfectly safe to use it in the Shed.

    There is no particular depth in the regs but that adequote depth to provide protection. If under a concrete path then its well protected from gardening tools. Although not safe from rodents.

    So when it gives an earth fault(RCD keeps tripping), its time to replace it with SWA.
     
  5. Spark123

    Spark123

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    Sorry, I agree with Adam on this. Flat twin and earth run in plastic pipe is not imo up to the job, even if it is RCD protected.
     
  6. diy_dude

    diy_dude

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    I have been given 25m of 4x10mm SWA cable. If I run this in the existing pipe will it be OK?

    I assume that I would been a small CU in the shed. I am concerned that connecting the SWA cable to the main CU in the house would be tricky, any suggestions how to do it?
     
  7. EddieCurrent

    EddieCurrent

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    Any chance of a picture of your consumer unit, or the make and model??, it will be easier to suggest methods of terminating the 'armoured' cable gland into it if we know what kind the unit is.

    Thanks
     
  8. bernardgreen

    bernardgreen

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    I used a die-cast aluminium box with SWA glanded into one end and the tails through a grommeted hole in the other end.

    The banjo on the gland has a earth lead to the earth block and the earth on the side of the box is an additional back up.

    [​IMG]
     
  9. diy_dude

    diy_dude

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    My CU is a Square D Domae unit. It was installed about 12 months ago. It is split load and has a spare 'way' on each side. It looks similar to this one although the layout of the breakers is different.

    [​IMG]
    Image 'borrowed from an ebay auction', was the closest I could find....

    I will try and get a photo of my CU in situ tonight and post tomorrow.

    Can anyone tell me if its OK to have the SWA in a 40mm waste pipe about 5cm below a concrete slab path.?
     
  10. kevnurse

    kevnurse

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    Although the existance of the upvc pipe, which is fine, will indicate something (it could be telecoms or water) to the person who lifts a slab, the perfect thing would be to lay an electricity warning tape the full length of the pipe on the sand directly below the slabs.

    As a DIYer, buying the min length of tape from the electrical wholesaler is a bind, because you'll never get through it all. But its the best way to advertise the electricity in the pipe.
     
  11. diy_dude

    diy_dude

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    Would I be Ok to have the SWA cable just below the sand with a warning tape above? Path laid above cable and tape to protect cable (and to walk on!!) Basically the same as above but without the 40mm cable duct.
     
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