sy cable glands

Discussion in 'Electricians' Talk' started by wheresthedog, Feb 12, 2020.

  1. wheresthedog

    wheresthedog Member

    Hi,

    Does SY cable need to have the braid terminated and earthed in a gland? I've had two different electricians do some work on the farm, their work seems tidy but neither has done anything with the braid within the plug sockets - just cut the braid and put a wrap of insulation tape on it.

    Thoughts please - are there any regs for this?

    Many thanks
    Paul
     
  2. peter palmer

    peter palmer Well-Known Member

    Depends on what its used for I suppose, SY cable isn't recognised for a distribution type of cable like SWA is, its classed as a control cable. If its being used for supplying say a compressor or something then it doesn't matter how its terminated it would still be wrong but if it was used as a control cable like a switch or signal cable for a machine then it should be terminated correctly in a brass gland. Saying that if it was safe enough to use a standard piece of flex in your situation I can't see how incorrectly terminating some Sy cable could suddenly make something dangerous.
     
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  3. wheresthedog

    wheresthedog Member

    It's being used instead of grey pvc cable from cu to sockets (2.5mm2) and lights (1.5mm2). That's where I get confused, why use any sort of armour protection if you're not going to terminate properly? No risk / don't use it or some risk / terminate it properly right?

    Would you mind explaining what a control cable is for please? Seems it not to deliver power to a socket?
     
  4. peter palmer

    peter palmer Well-Known Member

    This might explain it a bit better.

    https://www.whyprysmian.co.uk/sy-yy-cy-cable.html

    I don't think its particularly dangerous to use it for sockets and such like, its probably just standard flex under the braid anyway, its just not recognised as a distribution cable. You're not supposed to use it to supply an air conditioning unit power supply for example but could use it between the indoor and outdoor units of the air conditioning which more than likely carries the full 230V anyway.
     
  5. wheresthedog

    wheresthedog Member

    That's useful thanks. So basically not really an issue unless something goes wrong and someone such as an insurer finds out it was used in a fixed installation?
     
  6. dobbie

    dobbie Well-Known Member

    They do not comply with BS7671 which is the regulations for Electrical Installations, therefore at the the end of the day your installation does not comply with this. Any electrical installation certificate or minor works certificate you have been issued is useless because the cable does not comply.
     
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  7. wheresthedog

    wheresthedog Member

    hmm not a great situation
     
  8. Bob Rathbone

    Bob Rathbone Well-Known Member

    I would earth the braid at one end, whichever was the easiest to do. This will then ensure that should the cable be punctured or cut, the protective device would operate within the specified time and prevent or reduce considerably, the chance of electric shock.
     
  9. Bogle Crag

    Bogle Crag Active Member

  10. Tony Goddard

    Tony Goddard Well-Known Member

    SY is funny stuff, I'm not a big fan of it being used as a supply cable, but when we are kitting out and servicing machines in school workshops it is the type of cable specified for connection of the machine to the wall isolator, this is referenced somewhere in the BS for school and college workshops. It took over from BX cable which was previously very common, and is still popular in the states and oz. and which I prefer.

    There is a special gland for it which terminates the braids in two bunches gripped between washers, however we commonly see a metal cable clamp gland made by Lewden used for the same purpose.

    It can be terminated into plastic enclosures and commando plugs by carefully unpicking the braiding and re-twisting it into a single tight bunch, heat shrinked in green and yellow and then connected to the earth terminal, done properly that method is IMHO the best from a connection point of view.

    The manufacturers tend to deem it a control cable, meaning they won't take responsibility for it if used for power supply - however control can of course be running at 415v in some instances.

    I'm quite comfortable with it as hook up cable from machine to wall or making connections on the machine, or for the purpose of hard wearing extension leads, but I wouldn't use it as fixed (as in part of the installation) wiring myself.
     

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