SWA underground - using cable protection tiles

Discussion in 'Electricians' Talk' started by THexplodinghead, Jan 13, 2022.

  1. Bazza-spark

    Bazza-spark Screwfix Select

    I was a MIET for many years.

    I assume you are refering to this document.

    https://electrical.theiet.org/media...tdoors-a-supply-to-a-detached-outbuilding.pdf

    If the cable from the dwelling to the outbuilding is not armoured then the RCD goes at the dwelling end. If the cable from the dwelling is armoured the RCD goes at the outbuilding.

    If you have PME at the dwelling and are going to TT the outbuilding there must be an RCD in the outbuilding, rendering the RCD in the dwelling as much use as an ashtray on a motorbike.
     
  2. elecstick

    elecstick Member

    Now you're making it up, read the document it does not say what you want it to say, what I have quoted in post #16 is 100% correct.
     
  3. Bazza-spark

    Bazza-spark Screwfix Select

    Think its time you went back to school. That document was written in 2005, 13 years before the current edition of the regs.
     
  4. elecstick

    elecstick Member

    Now the insults start, why does it not comply with latest regs?
     
  5. Bazza-spark

    Bazza-spark Screwfix Select

    Not insults, facts.

    @spinlondon told you some posts back.

     
    BiancoTheGiraffe likes this.
  6. elecstick

    elecstick Member

    Now you drag someone else in to support your argument, and that person is wrong in their first statement, amazing how neither of you can see the real facts. And nothing has changed since 2005 to make my original advice incorrect, fact. Telling me "Think its time you went back to school" is an insult and thats another fact.
     
  7. Bazza-spark

    Bazza-spark Screwfix Select

    I haven't "dragged" anybody in. It was a post from page 1.

    The Regulations have changed since 2005. Telling you to go back to school and update your qualifications and knowledge is advice, not an insult.
     
  8. Bazza

    Bazza Screwfix Select

    @elecstick there are problems with your assertions about this article.
    This very short article is littered with words like “example” and “preferred method”. It is a guide and not a regulation.

    Where you have gone wrong is that in NO PLACE in that article, or on the diagram are the very important letters SWA to be found!

    You need to consider why SWA is used in installations, and how that type of cable alters any requirement for an RCD to be used at the source of supply. So yes, perhaps it’s time for some revision!

    PS it’s beyond my comprehension why IET did not include/require the use of SWA in their article!

    PPS The article is do old that it was produced at a time when the IET was called IEE.
     
  9. spinlondon

    spinlondon Screwfix Select

    The first 2 are still acceptable methods for providing RCD protection for any socket-outlets which would be used to supply mobile equipment outdoors.
    However they would not minimise inconvenience in the event of a fault.

    The second 2 are also still acceptable methods for providing RCD protection for any socket-outlets which would be used to supply mobile equipment outdoors.
    Further they would minimise inconvenience in the event of a fault.

    The last is no longer an acceptable method for providing additional protection.

    Not not only have the Regulations changed, so as to prohibit the use of SRCDs for additional protection, they also now require RCD protection be provided for domestic lighting circuits.
    As such the 4th is also no longer acceptable.

    Lastly, it should be noted, that the guide is the considered opinion of someone who is employed or associated with the IET.
    It does not form part of the Regulations.
     
  10. Tony Goddard

    Tony Goddard Screwfix Select

    I'm with the others, RCD goes at the shed end, SWA does not need RCD protection - depending on what you are feeding it's just going to cause problems - for example SWA to outbuilding supplying a DB with 4 RCBos, if you stick a 30mA RCD on the front end you defeat the discrimination and the ability to reset locally of the RCBo's, two devices tripping causing confusion for no benefit.

    Add to the fact many outbuildings are wired as a stand alone TT, the RCD then is integral to that TT set up.

    Back to the OPs question, 400mm fine, not tiles, yellow tape is far more obvious when digging.
     
  11. Hans_25

    Hans_25 Screwfix Select

    I have an outbuilding supplied with SWA and the RCD protection is in the outbuilding. My spark signed it off and that's a fact :)
     
  12. elecstick

    elecstick Member

    And if you read post #16, you will see there is nothing wrong with doing that, and he could also have put it at the other end and there nothing wrong with that either
     
  13. Hans_25

    Hans_25 Screwfix Select

    There may be multiple compliant ways to do, but that does not mean than one way isn't better than another.
     
  14. THexplodinghead

    THexplodinghead New Member


    Thanks for referring to OP - I have plenty of tape - I may still use some physical barrier where the trench is shallowest. I’ll also get a qualified person to view before any backfilling. Thanks
     
  15. Tony Goddard

    Tony Goddard Screwfix Select

    you could use tiles with tape over the top, I painted a load of tiles with road making paint once for a job!
     
  16. Bazza-spark

    Bazza-spark Screwfix Select

    The actual Regulation for general installations states:

    522.8.10 Except where installed in a conduit or duct which provides equivalent protection against mechanical damage, a cable buried in the ground shall incorporate an earthed armour or metal sheath or both, suitable for use as a protective conductor. The location of buried cables shall be marked by cable covers or a suitable marker tape. Buried conduits and ducts shall be suitably identified. Buried cables, conduits and ducts shall be at a sufficient depth
    to avoid being damaged by any reasonably foreseeable disturbance of the ground.


    For caravans and tent pitches:

    708.521.7.2 Underground cables
    An underground distribution circuit shall, unless provided with additional mechanical protection, be buried at a sufficient depth to avoid being damaged, e.g. by tent pegs or ground anchors or by the movement of vehicles.
    NOTE 1: A depth of 0.6 m is generally considered as a minimum depth to fulfil this requirement. Alternatively, the cable may be installed outside the pitch or other area where tent pegs or ground anchors may be driven.
    NOTE 2: For conduit systems buried underground, see BS EN 61386-24.


    And for agriculturual sites:

    705.522 Selection and erection of wiring systems in relation to external influences In locations accessible to, and enclosing, livestock, wiring systems shall be erected so that they are inaccessible to livestock or suitably protected against mechanical damage.
    Overhead lines shall be insulated.
    In areas of agricultural premises where vehicles and mobile agricultural machines are operated, the following
    methods of installation shall be applied:
    (i) Cables shall be buried in the ground at a depth of at least 0.6 m with added mechanical protection
    (ii) Cables in arable or cultivated ground shall be buried at a depth of at least 1 m
    (iii) Self-supporting suspension cables shall be installed at a height of at least 6 m.

    So you should be fine.
     
  17. THexplodinghead

    THexplodinghead New Member

    Thanks for this -I’ve been quoted the 600mm but I guess that’s not applicable for my case - I can relax a bit. Thks
     

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