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Koi Pond S.W.A Supply.

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The curtains open to reveal a tripped R.C.D. reported. The underground S.W.A supplies Koi Carp pond equipment such as water pumps, a U.V. unit and other stuff. Water ingress me thinks. The home owner says that the R.C.D. will not reset even with repeated tries.


I arrive to find that the owner has eventually got the R.C.D. to turn on.


Fault finding starts. The first section of S.W.A. cable reveals an insulation resistance of 0.03 Meg Ohms L to E. N to E o.k. 


The owner wants the faulty S.W.A to be reconnected. I say that I can not as the supply is unreliable and maybe dangerous. I refuse to reconnect it. I install a temporary supply for the pond to keep it airated and to prevent freezing. It is cold here.


The faulty section of S.W.A. cable runs to a socket at a shed  before continuing to the pond. I seem to recall in my dreams that the faulty S.W.A. cable is a 4 core type.


Do I use the 4th unused core as a new L if it tests O.K? YOUR THOUGHTS PLEASE.


P.S. Fencers have replaced an old fence with new posts, that is more than likely the cause of the damage to the cable.


Z.
  • 0
    You may reveal jacket damage by looking for impedance from the SWA armour to true terra-firma. If that is less than a few megs then it is likely. However, on its own a damp armour is not a reason to condemn a installation - surprisingly many installations are scuffed on installation and work OK for years.


    By all means use the existing core (or even god forbid swap the L and N ) to prove the point and get it going and keep the fish alive until better weather. If there is underground damage however, it is likely to get worse and eventually fail whatever you do, as water seeps into places it should not. However if the armour is complete from end to end it is unlikely to pose a serious risk while it fails.


    If you think the customer is the type to not get you back to change the SWA in a sensible time frame, do not offer this as an option.

    Mike.

  • 0
    You should have no objection to using another core with good IR, Z. XLPE is completely waterproof whatever may have happened elsewhere. Mike is quite right about the rest, however wet armour is not at all unusual.
  • 0
    I found that the black core was also showing a low resistance to earth. So I have installed a new cable. I was not sure of the potential underground damage to the original S.W.A. The owner said that the fencers used a "Jack Hammer" to make fence post holes. So some of the original S.W.A. cores or armour might have been hanging on by a thread. A section of the original S.W.A at the pond entered a plastic enclosure, then another looped out. The armour was not continuous but there was a separate protective conductor core. Not my work but I did not like that.


    At one point where an outgoing S.W.A. disappeared into the ground by the garden shed, below an outdoor socket, the armour was not earthed. The gland lock nut had rusted and could not be removed, so I was forced to fit an earth clamp to earth the armour. Not the best solution but it was the only one.


    Now the fish and owner are happy.


    Z.
  • 0
    I thought it was dolphins Z? Thanks for all the fish and so on.

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