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Safe zone with exposed beams

Discussion in 'Electrics UK' started by very_pointy_ears, 26 Feb 2018.

  1. very_pointy_ears

    very_pointy_ears

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    Hi,

    When a room has exposed beams, does the safe zone across the ceiling measure from the highest viewable surface, or from the bottom of the beams? I'm thinking about mainly the walls perpendicular to the run of the beams, ie the walls that the beam ends fix into.

    I've googled for ages to try to find an answer but no luck there.

    Not that I intend to make liberal use of safe zones without any visible fitting, but I'd like to know where I stand, just in case.

    Cheers,
    Kingsley.
     
  2. ban-all-sheds

    ban-all-sheds

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    There is probably no definitive answer.

    What's the depth of the beams?
     
  3. EFLImpudence

    EFLImpudence

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    The definition is "within 150mm. from the top of the wall" - so...
     
  4. JohnW2

    JohnW2

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    Indeed. However, as I see it, even if one decided that the 'top of the wall' went up and down around the beams (so that there was 150mm of safe zone below the bottom of the beams, where they existed), then, if the beam were more than 150mm deep, one would not be able to get from the 'upper' safe zone (150mm from the 'actual ceiling') to the perceived safe zone below the beam without passing through something which was not a safe zone.

    Kind Regards, John
     
  5. very_pointy_ears

    very_pointy_ears

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    Beam depth is 6 inches ...

    Meanwhile, in surveying the electrics, I found this behind one of the kitchen sockets ... and I *know* that white cable is feeding a spur. Yes, that is a 1mm cable in there, no gromits and no earthing on the pattress.

    In fact, I've found the kitchen circuit feeds sockets in one of the downstairs rooms as well and most, but not all, of the sockets in one of the bedrooms. What's more, the double light switch between the utility and garage has each switch on a completely different circuit, there are other spurs off spurs, and the kitchen circuit isn't one of the RCD protected ones. To say this installation is random, if not just dangerous ...
     

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  6. EFLImpudence

    EFLImpudence

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    That's not actually a requirement as long as the socket is.

    No problem - apart from calling/labeling it a kitchen circuit.

    Not a problem. Common practice.

    Probably needs sorting.

    Neither is mine. Whether it contravened the regulations when fitted depends when it was fitted.
     
  7. very_pointy_ears

    very_pointy_ears

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    You've surprised me there. I thought the pattress had to be earthed so that the screws were.

    I'm also surprised that it's acceptable, even common practice, to have different circuits in the same switch fitting.

    I do presume that the 1.0mm cable spurred of the kitchen sockets is potentially a fire hazard, especially as that 1.0mm cable then goes behind the Aga.
     
  8. EFLImpudence

    EFLImpudence

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    It is specifically not allowed - it could be overloaded if it supplies a double socket.
     
  9. JohnW2

    JohnW2

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    So long as there is an earth connection to the socket, the screws will be earthed by that, as will the back box when the screws are done up. Explicit earthing of the back box (with a wire) is, in my opinion, preferable, but earthing it via the faceplate screws is theoretically acceptable.

    Kind Regards, John
     
  10. very_pointy_ears

    very_pointy_ears

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    To be fair to whoever did it, it only supplies a single socket that has a small PSU drawing about 30 watts (thermostat control for the Aga). But, a fault couldn't be relied upon to be able to trip the 32A breaker before the cable melted, I would have thought.
     
  11. JohnD

    JohnD

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    If you were to put a fused connection unit at the source, next to the socket it spurs from, you could fuse it a, say, 3A or 5A

    Unswitched or somebody will turn it off. And preferably labelled (the PSU socket too)
     
  12. EFLImpudence

    EFLImpudence

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    Then that will be technically fine but as I said 1mm² twin and earth - not flexible cable - is specifically prohibited on a "power" circuit - whatever that is.

    Yes it can (be relied upon).
    One socket means not more than 13A could be drawn - let alone your 30 Watts, and -
    a short circuit will trip the 32A MCB before the cable melts.
     
  13. EFLImpudence

    EFLImpudence

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    That's not necessary; the cable (if twin and earth) is good for 16A.
     
  14. DetlefSchmitz

    DetlefSchmitz

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    Well, if the bottom of the beam can be considered a ceiling then the sides can be considered a wall...
     
  15. JohnW2

    JohnW2

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    Yes, that's true. However, I can't help but feel that both those 'considerings' are probably pushing things a bit.

    Kind Regards, John
     
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