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How do you decide where to drill the ceiling

Discussion in 'Electrics UK' started by Jupiter01, 17 Jun 2021.

  1. Jupiter01

    Jupiter01

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    When there are cables popping through the ceiling in this manner and you need to drill some holes for the light fitting, how do you determine where to drill them and not poke a hole into the cables.

    There is no access to the cables above the ceiling.
     

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  3. conny

    conny

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    You could try pushing a thin screwdriver blade through and then giving it a waggle to see if you feel any resistance. If you can then there are probably cables where you have poked through. If you can tilt the screwdriver at an angle and then swing it in a full circle the chances are there are no cables near that hole.
    Not guaranteed of course and you may, (hopefully should), hit a joist. If you do hit the joist then that is where you drill to support your fitting.
     
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  4. sparkwright

    sparkwright

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    Should be no need to do any drilling. Using a drill risks damage to cables and pipes. Fitting screws by hand gives you more control to anticipate such dangers.

    Use a thin screwdriver as Conny has described, when you feel the wood just screw the woodscrews in by hand.

    (Pozi screws are easier to control.)
     
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  5. blup

    blup

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    How heavy is the fitting? If you can't find a joist or lath, or the plasterboard is too weak, you may be able to get a strip of wood above the ceiling by removing some of the plaster, screwing into the wood from beneath. The hole needed for the strip of wood will allow closer inspection of cable location. Attach the fitting to the wood strip, which can also anchor any repair.

    Blup
     
  6. Sureitsoff?

    Sureitsoff?

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    from the pic and the position of the current screw holes it looks like the joist runs right left and is in front of where the cables are
     
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  7. Jupiter01

    Jupiter01

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    Often I have been installing a lightweight fitting and on occasions, just a pendant. Both of these can be fixed to the plasterboard with appropriate plugs in my experience. To be honest, I have used a drill in the past and always dreaded the worst!

    I don’t understand what you mean by poking a screwdriver when there are no holes in the desired location.
     
  8. conny

    conny

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    Where the current holes are from the old fitting, (1 to the left of the cables and one further over to the right of the cables), use a thin bladed screwdriver, (such as a terminal screwdriver with a blade length of at least 4"), to poke up into those holes. If there is a joist behind those holes it will stop the driver being pushed all the way in. If the blade goes deep with no resistance then there is no joist in that location.
    If the joist is located behind those two holes then you know it runs right to left and you can safely screw in to the joist without hitting the cables. If the joist is not in that position then you simply poke new holes in the surrounding area. Using a thin blade will ensure minimum filling in after you locate your desired position.
     
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  9. blup

    blup

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    A neodymium magnet will identify the location of the screws in the plasterboard - if that's what you have - and help identify not just the location but also the width, of the joist.

    Blup
     
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  11. AndyPRK

    AndyPRK

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    I tap the ceiling and listen to note changes.
    When you get a lower tone there is a beam.

    if you do this across a large area and identify 2 beams, you can measure the distance between the beams. This can help give you an idea of beam spacing if you aren’t sure there is a beam by the light

    You can also drill a tiny test hole, and then poke a bare earth wire thru. And if its just fresh air above, you missed the beam
     
    Last edited: 20 Jun 2021
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  12. Jupiter01

    Jupiter01

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    With this approach, if the fitting isn’t heavy, can’t I just use my regular 6mm drill bit and drill carefully I.e stop as soon as I poke through the plasterboard? At this stage I can either plug if it’s hollow or screw into the timber if I’ve hit a joist? I wanted to understand the approach when the light fitting isn’t heavy and hence, doesn’t necessarily require a joist for fixing.
     
  13. Harry Bloomfield

    Harry Bloomfield

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    Almost certainly the cables will be alongside a joist, so you can fix the rose/fitting, so poking a screwdriver up the hole the cables appear through, should mean you can feel the joist with the driver. Knowing where the joist is, you can fix to it - just poke a thin screwdriver through the plaster, to ensure you hit the joist, for you first fixing - keeping in mind your rose/fitting needs to cover the cable hole and get a second fixing into the joist.
     
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  14. AndyPRK

    AndyPRK

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    Yes.

    As said, it’s always nice to get one screw in wood
     
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  15. Risteard

    Risteard

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    Scrulox are better.
     
  16. conny

    conny

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    Can't believe this has had 12 replies and we still don't know if the light has been fitted! :rolleyes:
     
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  17. Munroist

    Munroist

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    indeedy, the magnets out of old hard drives are just amazing and a wonderful way of finding screw heads hidden under plaster, (use a little clean tissue between to stop the dirty marks them leave) Once you have found the screwheads you can work out where the joists are - not sure how this tells you the width of the wooden joist, you just have to assume the person putting them up got the screws in the centre. So much better than any electronic joist finder I have used.
     
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