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ceiling grids

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  • 11-04-2011 9:33am
    #1
    M cebee
    Closed Accounts Posts: 4,431 ✭✭✭


    an engineer recently suggested that i should be earthing concealed metal 'ceiling grids'

    my understanding is that you keep the wires off the grid

    - and as the grid isn't exposed or extraneous it shouldn't be earthed or bonded

    i know some guys drape the cables on the grid and 'earth' the grid-but i think this is wrong and hazardous

    what do you guys think


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    #2
    Bruthal
    Closed Accounts Posts: 13,422 ✭✭✭✭Bruthal


    I earth it anyway. And keep the cables up off it.


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    #3
    mfceiling
    Registered Users Posts: 12,840 ✭✭✭✭mfceiling


    Is it the grid ceiling with tiles or the metal framed ceiling with plasterboard?
    Most sparks keep the cables tied up to each hanger.
    As for earthing the grid the edges are normally fixed to the block walls and the hangers are attached to the concrete slab......would this earth the ceiling?


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    #4
    Bruthal
    Closed Accounts Posts: 13,422 ✭✭✭✭Bruthal


    mfceiling wrote: »
    Is it the grid ceiling with tiles or the metal framed ceiling with plasterboard?
    Most sparks keep the cables tied up to each hanger.
    As for earthing the grid the edges are normally fixed to the block walls and the hangers are attached to the concrete slab......would this earth the ceiling?

    That wouldnt earth it very well, not well enough to trip a circuit MCB, the idea of earthing the metal grid would be if a live cable conductor came in contact with the grid from the grid cutting through the cable insulation, it would trip the circuit MCB rather than the grid becoming live and going un-noticed. For this to happen the grid would need an earth wire connected to the distribution board from the earth.

    Also all metal work would be earthed in neutralised installations so if the neutral broke, all metalwork would be at the same potential at least, which reduces shock risk, even though the broken neutral/earth bar could be up to the 230v mark.

    The grid is not exposed to touch, and the cables may be above it and not in physical contact, but at a later stage someone could fish a cable from one position to another and it would end up lying on the grid.

    At the same time, maybe non exposed, non extraneous metal does not need earthing, but with a grid being a large metal part in each room, i would earth it anyway.


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    #5
    M cebee
    Closed Accounts Posts: 4,431 ✭✭✭M cebee


    concealed mf grid

    how do you earth it robbie


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    #6
    Bruthal
    Closed Accounts Posts: 13,422 ✭✭✭✭Bruthal


    The last time i did it was in a big house, it was a heavier type grid (i think it was anyway) than the standard metal they use in commercial partitions and mf grid ceilings so i earthed it. I put 4mm bolts through all the ceiling grids in various places and lugged earths onto it.

    Id say ye have a point about not earthing it too though and is something i thought about a few times before, are they saying the metal in the wall partitions and all should be earthed?


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    #7
    M cebee
    Closed Accounts Posts: 4,431 ✭✭✭M cebee


    the metal stud on walls is different -that takes a local bond from nearest protective conductor


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