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Drilled through light switch cable

Discussion in 'Electrics UK' started by adamthekiwi, 16 Oct 2017.

  1. adamthekiwi

    adamthekiwi

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    Hi folks,

    I've drilled through the cable to a light switch (I think - the voltage detector didn't detect the cable prior to drilling, and it's a fair bit away from the vertical channel above the switch) - the only symptom is that the switch is not working. Nothing tripped in the consumer unit.

    The wall is plaster over (very old) brick - there is very little room to effect a repair. Chasing the cable out of the wall is also going to be very difficult indeed - there is a mezzanine platform in the way. The only way into the ceiling space will involve cutting through the lathe and plaster or removing the bathroom floor upstairs.

    For this reason, I'd like to try a crimped repair covered with self-amalgamating tape and plastering the fix back into the wall (assuming I can find the break!). Viable?

    Cheers - Adam...
     
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  3. John D v2.0

    John D v2.0

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    Crimping would be fine, not sure about the tape.
     
  4. bernardgreen

    bernardgreen

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    Plastering over the joint is not good practise and is probably non compliant with BS7671.

    The break, if there is one, will be very close to the hole you drilled.

    It might be by co-incidence that the switch has failed, or a terminal has become loose ( in switch or ceiling rose / light fitting )
     
  5. JohnW2

    JohnW2

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    It's certainly not something I would do, but I can't think of anything in BS7671 which specifically forbids it - crimping is one of the types of joint which is, after all, explicitly allowed to be 'inaccessible'.

    Kind Regards, John
     
  6. aptsys

    aptsys

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    Nothing at all wrong with crimp and self-amalgamating tape. Just make sure you use the correct crimps and crimp tool.
     
  7. ericmark

    ericmark

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    If the hole you drilled is outside of the safe zone for cable then although you can repair it question is do you want to repair it? When you don't know it's there clearly you can't correct, but once you know then should you ignore it is another question.

    However drills vibrate so before digging out around the hole, just remove the switch and see if something simple like a screw loose and wire popped out. Also of course check bulb and wires in ceiling rose.

    While getting into loft my wives bedroom light went out, cause was loose wire in landing ceiling rose, getting into loft was enough vibration to dislodge the wire. Look for easy bits first.
     
  8. ban-all-sheds

    ban-all-sheds

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    Re-energising and putting back into service a cable concealed in a non-compliant way?
     
  9. DaveHerns

    DaveHerns

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    Will there be enough slack in the cable to bring the ends together?
     
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  11. JohnW2

    JohnW2

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    Maybe (I suspect opinions might vary), although it would presumably be the repairing that could be the issue, not the "re-energising and putting back into service" - after all, flipping the circuit's MCB off and on would presumably not bring about a regulatory requirement to re-route (or protect) the cable!

    Kind Regards, John
     
  12. JohnW2

    JohnW2

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    There presumably will be no slack if the cable is plastered in. I therefore presumed that it was being proposed to insert a short new length of cable, hence with two sets of crimped joints.

    As I have implied, quite apart from regulations, I personally would not want even one set of any sort of joints (crimped or otherwise) buried in plaster, but perhaps that is just me.

    Kind Regards, John
     
  13. ban-all-sheds

    ban-all-sheds

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    If a short length of cable is interposed, then there can be no doubt that it would not be compliant to have it buried where the damage is.


    No doubt, were it not that during the discussion of this aspect nobody has thought to ask if the cable is in a corner or ceiling zone.....
     
  14. sparkwright

    sparkwright

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    There's a lot we don't know, such as whether this cable is in a safe zone, in a conduit, or even if it definitely is damaged.

    Pictures would be handy.

    If crimping is to be done, I would prefer the joint to be sleeved with heat shrinking, FWIW.
     
  15. ban-all-sheds

    ban-all-sheds

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    CBA to look - what do the regs say, if anything, about containment of single-insulated, or insulated-and-unsheathed, conductors?
     
  16. aptsys

    aptsys

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    How do you figure this?
     
  17. ban-all-sheds

    ban-all-sheds

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