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S.W.A. Armour Earthing.

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Which regulations(s) require the steel wire armouring of a S.W.A. cable to be earthed if it is NOT used as a circuit protective conductor?


Case 1. Cable buried underground.


Case 2. Cable NOT buried underground.


Z.
  • 0
    444.5.3.1

    That's if the swa is used for data transmission cables or IT equipment connected to an equipotential bonding network
  • 0
    Jon Steward:

    444.5.3.1

    That's if the swa is used for data transmission cables or IT equipment connected to an equipotential bonding network


    O.K. But if it is not used for such?


    Z.


  • 0
    The armour is cable containment, so as such it is an exposed conductive part, and must be Earthed to cause automatic disconnection of the supply.. 411.3.2


    I assume you are trying to have some kind of competition or was this a genuine inquiry. I refer you to the index of BS7671, exposed conductive part.
  • 0
    Maybe that’s the point Z is making, is the wire armour an exposed conductive part. Maybe not according to the definition.
  • 0
    I would say that unless strictly prohibited ALWAYS earth it  after all its in very close proximity to live conductors and if someone slices thru the cable by accident it lessens the chances of the person getting a fatal shock. Case in point my dad sliced thru an swa cable whilst making holes for fence posts he didn't feel a thing but it took out  all 3 of the main fuses for the  building
  • 0
    well if the SWA was glanded into a plastic box, the external part of a metal gland would certainly be an exposed c.p.
  • 0
    Case 1: 522.8.10 (except where installed in a conduit, etc.) cabled buried in the ground is to have an earthed armour, etc.


    Case 2: it depends.


    If buried in a wall, or passing through joists, the armour is to be earthed: 522.6.202 to 522.6.204 .


    If clipped direct, provided the cable has been made off in such a way that the armour cannot be touched, e.g. in a plastic gland, there is no ECP and therefore no requirement for earthing - see Part 2.
  • 0
    lyledunn:

    Maybe that’s the point Z is making, is the wire armour an exposed conductive part. Maybe not according to the definition.


    I have an old copy of Guidance Note 8 2004. It says that even when the armouring is not in service as a protective conductor it still has to be earthed as it is an exposed-conductive-part.


    But is it?



    Case 2. 

    If the glands are shrouded the brass glands can't be touched. The armour can't be touched as it is covered in insulation. And if glanded into an insulating plastic enclosure all is safe init? Is the armour really

    an exposed-conductive-part?


    Z.


  • 0
    davezawadi (David Stone):

    The armour is cable containment, so as such it is an exposed conductive part, and must be Earthed to cause automatic disconnection of the supply.. 411.3.2


    I assume you are trying to have some kind of competition or was this a genuine inquiry. I refer you to the index of BS7671, exposed conductive part.


    Suspicious David. No competition here, just a serious enquiry.


    Z.


  • 0
    You do try to have competitions sometimes!


    As many have said on here many times the sheath should not be considered insulation, it is mechanical protection. The core plastic is insulation, the bedding layer is not, just packing, so the armour is an exposed conductive part even if sheathed. is plastic-coated metal trunking or conduit an exposed conductive part? Yes, because unlike the cores it is not insulation tested with a water bath at manufacture, and whatever YOU do, may have defects you have not noticed. Is this part of an EICR, because this should be a code 2, but is obviously easily fixed with a new metal gland etc. The plastic hoods over glands are not insulation, they can easily be pulled back, they are environmental protection for the armour.

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