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SWA Cable Above ground and earthing the armour

sparkiemike
When using SWA cable underground I always earth the armour, regardless of whether the armour is used as the cpc or not. The armour does provide some mechanical protection and it is important that the armour is earthed so that if the cable were penetrated (e.g. by a garden fork), the supply would automatically be disconnected by the protective device under this fault condition.
I have a situation on an existing domestic installation where I will be changing the consumer unit.  The 3-core SWA cable to the hot-tub rotary isolator is above ground and clipped to an outside wall.
The cable has not been terminated with brass glands, and at the ends the armour have been taped up, so no exposed conductive parts. The armour is not being used as the cpc.
At the rotary isolator for the hot-tub, stuffing glands have been used. The cable feeding the hot-tub does rest on the ground for about 1m before going into the hot-tub enclosure.
The earthing arrangement is TNCS, however at the hot-tub rotary isolator, the TNCS earth is not exported and there is an earth electrode for  the hot-tub’s cpc
Would you expect the armour to be earthed? Is it acceptable to terminate SWA without brass glands?
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    Chris Pearson:



    Zoomy, who said that the cable is on the ground?


    What's the alternative - a bit of T&E. There's a bit of T&E at daughter's house which is dry and crazed. She got a bit upset when I started digging with my thumbnail. ? The plan is to replace it with some T&E, but perhaps I am being misguided - is SWA better, or worse, or the same, when it comes to exposure to sunlight (on a south-facing wall)?


     




    I did 



    The cable feeding the hot-tub does rest on the ground for about 1m before going into the hot-tub enclosure.


  • 0
    In addition to the SWA problem there are some other problems that I will be fixing, but did not to get into them before hearing some views from people here. The replies here have been useful, so thank you.


    To give you an idea of the other issues, here is what I found when I opened the isolator...
    0df26817bfd352034247249afa2bdac6-huge-untitled-1-copy.jpg

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    That's beyond belief. 


    Whoever connected that up hasn't got the faintest idea of what to do.
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    Rather rough certainly - at least all the incoming wires are on the same side of the isolator, I suppose that is something . Even if  it has done because there is a desire to not expose a bare earthed gland on the outside of the plastic box,  it would have been quite possible to comb and connect the TNC-s  to the armour strands in a block here, although a proper gland at the origin would be much better.

    The use of tape in such an ugly way is not nice, but on its own scarecly a fail, The 2 sizes of SWA are interesting choices.

    As soon as you don't earth the armour, it loses its ADS firing potential and may  as well be T &E behind something giving a bit of mechanical support, like a bit of foil back plasterboard or something. And that really restricts where  you should use it.
  • 0

    sparkiemike:




    Chris Pearson:



    Zoomy, who said that the cable is on the ground?


    What's the alternative - a bit of T&E. There's a bit of T&E at daughter's house which is dry and crazed. She got a bit upset when I started digging with my thumbnail. ? The plan is to replace it with some T&E, but perhaps I am being misguided - is SWA better, or worse, or the same, when it comes to exposure to sunlight (on a south-facing wall)?


     




    I did 



    The cable feeding the hot-tub does rest on the ground for about 1m before going into the hot-tub enclosure.



     




    I must polish my reading glasses. ?

  • 0

    Sparkingchip:

    That's beyond belief. 


    Whoever connected that up hasn't got the faintest idea of what to do





    Switched earth
     

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    unusual certainly, and it is only OK to switch earth when mechanically ganged with the current carrying cores, as it is in this case. 

    I agree, it is far from  standard, and rings alarm bells as to if there is something really serious wrong elsewhere.
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    There is an unused earth terminal within the switch enclosure.
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    mapj1:

    unusual certainly, and it is only OK to switch earth when mechanically ganged with the current carrying cores, as it is in this case. 

    I agree, it is far from  standard, and rings alarm bells as to if there is something really serious wrong elsewhere.




    I doubt whoever wired it would be trying to claim compliance with 543.3.3.101 No switching device shall be inserted in a protective conductor, except: (ii) a multipole, linked switch in which the protective conductor circuit is not interrupted before the live conductors and is re-established not later than when the live conductors are reconnected.

     In my mind I think it’s a case of they had cables with three conductors and there’s three terminals on each side of the switch so used those rather than the earth terminal provided and that protective conductor is not switched through a switch designed to allow it to make first and break last.


    Andy 

  • 0
    I don't think that the rotary isolator complies with 543.3.3.101 so can't be used to switch the cpc. In addition there are two spare unswiched terminals within  the enclosure that have not been used.

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