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E.L.V. Garden Bollards.

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A customer has some underground S.W.A. cable supplying three low level garden lights. The installation is amateurish and now keeps tripping off an R.C.D. He does not want the garden dug up to replace the cable with bad underground joints at the lights. I was wondering if E.L.V. lights could be used at say 12 or 24 Volts via an isolating transformer. Does anyone know of a suitable type of light please? That way the S.W.A could be reused.


Z.
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    This one would niggle me to the "let`s do it right option". re-cable the job or walk away methinks
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    ebee:

    This one would niggle me to the "let`s do it right option". re-cable the job or walk away methinks


    When passing by the house next I will have a proper look at the planted bollards in the lawn. The customer does not want the lawn dug up to replace the S.W.A. cable. If I can not offer a reliable option I will say so and walk. But the customer may have more work for me of a different kind so I do not want to appear awkward.


    Z.


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    ELV AC from a small transformer and ELV LED lamps. Warn customer IN WRITING that no waranty can be offered due to doubtfull condition of existing cables.
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    Thanks broadgage,

                                      after having slept on this matter, I have decided not to proceed with any kind of repair work. The installation was never correct and was not reliable and never will be. I am not going to dig down to find taped chock block connectors buried in soil, rusty and rotted. The cables can not be reliably and correctly repaired. This is the result of a cheap poor installation. The customer must learn by his stupidity and meanness. You can't build a solid house on poor foundations.


    Z.
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    Another option might be to run new ELV cable and abandon the existing.

    It is in my view acceptable to install "hi-tuff" or similar at a very shallow depth if it is only for ELV. Gardening operations might damage the cable, but there would be no electrical danger.


    Cable may be shallow buried under a lawn without any damage to the lawn. Start at one end of the cable route and drive a spade into the soil. Lever the spade sideways without removing any soil. Poke the cable into the slit, and repeat along the run. Tread the displaced soil back into place.


    Not suited for mains voltage, but fine IMHO for ELV at a limited current.
  • 0
    broadgage:

    Another option might be to run new ELV cable and abandon the existing.

    It is in my view acceptable to install "hi-tuff" or similar at a very shallow depth if it is only for ELV. Gardening operations might damage the cable, but there would be no electrical danger.


    Cable may be shallow buried under a lawn without any damage to the lawn. Start at one end of the cable route and drive a spade into the soil. Lever the spade sideways without removing any soil. Poke the cable into the slit, and repeat along the run. Tread the displaced soil back into place.


    Not suited for mains voltage, but fine IMHO for ELV at a limited current.


    Yes, I have seen that method used to run audio cables from a large mixing desk to a stage in a lawned park for a two day concert. After the concert, the cables are removed, the turves replaced, and nothing seems different. No damage is apparent.


    Z.


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    It is in my view acceptable to install "hi-tuff" or similar at a very shallow depth if it is only for ELV.

    522.8.10 would seem to suggest otherwise. It's a bit daft as bell wire inside some flimsy flexible plastic conduit would seem to comply but inherently robust composite cables not. Not clear what protection an earthed metal sheath is meant to provide for an ELV circuit, especially a SELV one, or how to judge 'equivalent protection against mechanical damage' (as distinct from protection from electric shock resulting from mechanical damage).


    In any event you've still got the requirements for covers/marking tape and sufficient depth (many lawns get aerated with a garden fork...)


       - Andy.

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    AJJewsbury:
    It is in my view acceptable to install "hi-tuff" or similar at a very shallow depth if it is only for ELV.

    522.8.10 would seem to suggest otherwise. It's a bit daft as bell wire inside some flimsy flexible plastic conduit would seem to comply but inherently robust composite cables not. Not clear what protection an earthed metal sheath is meant to provide for an ELV circuit, especially a SELV one, or how to judge 'equivalent protection against mechanical damage' (as distinct from protection from electric shock resulting from mechanical damage).


    In any event you've still got the requirements for covers/marking tape and sufficient depth (many lawns get aerated with a garden fork...)


       - Andy.

     


    522.8.10 is obviously aimed at L.V. not E.L.V. The use of the expression "suitable for use as a protective conductor" is a give away..


    Z.


  • 0
    AJJewsbury:
    It is in my view acceptable to install "hi-tuff" or similar at a very shallow depth if it is only for ELV.

    522.8.10 would seem to suggest otherwise. It's a bit daft as bell wire inside some flimsy flexible plastic conduit would seem to comply but inherently robust composite cables not. Not clear what protection an earthed metal sheath is meant to provide for an ELV circuit, especially a SELV one, or how to judge 'equivalent protection against mechanical damage' (as distinct from protection from electric shock resulting from mechanical damage).


    In any event you've still got the requirements for covers/marking tape and sufficient depth (many lawns get aerated with a garden fork...)


       - Andy.

     


    I agree that my proposal might not comply with the regulations. In view of the negligible risks, it would however be a reasonable departure.


  • 0
    522.8.10 is obviously aimed at L.V. not E.L.V. The use of the expression "suitable for use as a protective conductor" is a give away..

    I don't think that adds up - you can have protective conductors on ELV - both FELV and PELV - and LV systems without protective conductors are possible too - e.g. separated systems for single items of equipment and fully double/reinforced insulation (a c.p.c. has to be included for the latter in domestic and similar uncontrolled installations of course, but as a general principle it's not required).


    Given the wording and position of 522.8.10 I don't think it can avoided as reading that it should be applied to all systems - if it was intended as applying onto the ADS systems only then section 411 would have been a more obvious location for it for example. Some might think that many of the other provisions (depth, marking tape and so on) would be sensible for any system. I guess they're expecting us to use the conduit/duct option where there isn't a c.p.c. The near-by regulations for cables concealed in walls have an explicit get-out for SELV & PELV circuit - so clearly the 522 section in general is intended to be read as applying to ELV too.


    A while ago in response to one of the DPCs I did suggest an exemption for SELV at least for the earthed sheath/armour bit (and I gather through the grapevine that it was discussed - so the committee are aware that it is being read as applying to SELV/PELV systems) but seem to have decided not to change it.


       - Andy.

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