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Cable capping

Discussion in 'Electrics UK' started by lasors, 21 Jun 2010.

  1. lasors

    lasors

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    We're in the process of getting quotes done for a house rewire. I was told today that capping is required for all cables in walls that are buried less than 50mm. Is this correct? I was previously under the impression that if RCBO protection was installed then capping wasn't necessary. I've cut chases already (only 6 of), 25mm wide, which is too narrow for capping. Must any mechanical protection be metal? If so will galvanised conduit do the job? Should it need to be earthed?

    Thanks!
     
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  3. Steve

    Steve

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    It doesnt have to be capping. Oval tube can be used instead.

    The tube or capping is just there to protect the cable from the plasterers trowel, and can be helpful for rewiring in future. It offers no mechanical protection from drilling, and needn't be earthed if metal.

    Galv conduit can be used as part of an RCD-avoidance tactic, but will cost more than an RCD to install. ;)

    How did you cut the chases? Diamond saw?
     
  4. lasors

    lasors

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    Thanks Steve.

    That's what I thought. I'm not recutting the chases if I don't really need capping. Anything I can do to cut the cost is welcome, as the price was over £3k for a 2-bed terrace. The house is empty and all chasing and socket sinking will be done by me, as will all the plastering and making good.

    Yes, I used a wall chaser with twin diamond blades. It wasn't desperately expensive and was quite fast, dust isn't an issue as the house is largely empty and the attached vacuum got most of it.

    There is capping already fitted to the light switch runs to the ceiling, but I've been quoted for RCBOs anyway. Even if I don't need them I figure they're a good idea.
     
  5. 1john

    1john

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    Capping does not provide adequate protection to cables buried less than 50mm from the surface.
     
  6. lasors

    lasors

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    Do you mean metal or plastic? What do you advise should be done, John?
     
  7. ColJack

    ColJack

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    either..
    he means for exclusion of the RCD protection..
    if it's not earthed metal and surrounding the cable ( which it's not since the cable sits on the brick. ), then it's no good for use as "an earthed metalic sheath", and it certainly doesn't offer suitable mechanical protection..

    if it's a total rewire then odds are that he's quotong for dual rcd board or rcd / rcbo combination board.. so no further action regarding cable protection needs to be taken providing the cables are within the specified "safe zones".
     
  8. 1john

    1john

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    If you are looking to prevent having RCDs on circuits, if so then steel conduit is the way to go. If you are looking to be able to pull cables through in the future and are happy to have RCDs then use oval conduit. If you just want the house rewired and dont care about pulling cables in again in the future just clip them to the wall.
     
  9. lasors

    lasors

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    I'm not necessarily looking to prevent having RCDs on circuits, as surely they are a good thing to have? I imagine this wiring will be good for the duration of our ownership so I could just clip them in and plaster over, but for all it costs, oval conduit might not be a bad idea.

    Yes, ColJack, I was quoted for RCBOs but reusing the present CU which was updated not long ago when a new electric oven was installed for the previous owner.

    I've read all the 'same as a second hand car' lines about quotes for electrical work, but if I give a detailed list of what we're having done would anyone kindly comment on a ball park price for the work? £3100 seems awfully high to me.
     
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  11. Steve

    Steve

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    3 grand sounds a bit steep IMO. :eek: Especially as it sounds like you are doing the donkey work. :confused:

    I just paid £850 (though it was sort of mates rates in his spare time) for:

    lighting rewire. new consumer unit. 6 extra sockets (covering every room). eq bonding. cable to loft for future CH circuit. socket in loft for booster. cable to loft for future shower circuit. cables to above kitchen for future division of ring mains when ktichen is done. new cooker circuit. back boxes supplied and chased for data and co-ax cabling.

    Turned out being almost a total rewire. Original quote was £600 for lights and 2 extra sockets.

    Total rewire of a 2 bed terrace, with all routes exposed and ready to lash cables in with no making good, maybe 2-3 good days work, £2000 tops including Parts and labour.
     
  12. sparkwright

    sparkwright

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    Since this is your house, and you have only cut six chases, you would be advised to use plastic capping or oval conduit. It costs virtually pennies to buy.

    Many times I have been able to alter wiring later on, thanks to capping and conduit. It is a far superior job imo.
     
  13. 1john

    1john

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    3100 seems high, but what are you getting and what are you doind towards the work....
     
  14. lasors

    lasors

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    Hopefully I've thought of everything, list below. No finishing is required. All chases and socket recesses will be cut by me. The house is not being lived in, it's not empty but furniture is already piled out of the way so floorboards can be lifted. Kitchen is out. I can supply parts but not sure whether I'll get them that much cheaper than trade plus mark-up.

    Hall
    1x single socket
    1x 2way light switch

    Living room
    6x double sockets
    2x 1way switches
    Ignition spur for gas fire

    Kitchen
    4x double sockets
    1x high level spur for extraction hood
    1x low level single socket for dishwasher
    1x cooker point plus gas hob ignition
    1x 1way light switch

    Utility
    1x double socket, surface mounted spur
    2x 1way light switches

    Bed 1
    4x double sockets
    1x 2way light switch with ceiling pull cord
    1x 1way light switch in cupboard

    Bed 2
    4x double sockets
    1x 1way light switch

    Toilet
    1x 1way light switch
    1x fused spur for towel radiator element (dual CH/electric)

    Bath
    1x 1way light pull cord
    1x electric shower (nearly new install, just needs cable rerouting from current surface mount down stairway)

    Landing
    1x 2way light switch

    Loft
    1x 1way pull cord light

    2x mains smoke alarms
    1x 1way light switch
     
  15. bongos

    bongos

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    I wouldn't go supplying the materials for the spark for the rewire as you won't save money that way but I would go getting other quotes.

    I don't know about the WM but in Sheffield in an empty two bed terrace for what you are getting done that sounds expensive indeed. Especially as you are doing all the chasing and box sinking... :confused:

    Did you get other quotes?
     
  16. lasors

    lasors

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    Other quotes are scheduled to be done. I had no idea if this quote was the sort of price I was really looking at, as I was initially expecting it to be much less. If others agree it is too high, I know I should be expecting to be quoted lower, so I know where I stand in that respect.
     
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