The Ultimate PME/TNS Exportation! B-)

Discussion in 'Electricians' Talk' started by sinewave, Mar 25, 2007.

  1. wklivesvtime

    wklivesvtime New Member

    why does that matter ld? Prob at the next joint back but i dunno. Need dno exp to know the regs where and how often they have to
     
  2. sparkin!

    sparkin! New Member

    me, NOW, GAME OVER!
    but sine, that post you made is bxxxxxx!;-)
     
  3. Lokkars Daisy

    Lokkars Daisy New Member

    wikls, I am off to basics , most concern amongst the many when running a supply to a remote building from a pme supply is the possibility of the extraneous conductive parts in the remote building (tied to the pme earth) being at a potential above the true earth about the remote building .
    Ask yourself why does this happen.
     
  4. Reg Book

    Reg Book New Member

    Unless you were the DNO why would you actually want to export a PME earth?

    An installation only has 1 MET at the origin of the supply (PME or not).

    Services have to be connected bonded back to the MET even if the installation serves more than one building 413-02-02 - Main Equipotential Bonding Conductor required. Can combine with the CPC 547-02-01

    You can TT in which case you get anothe MET and dont need a CPC.

    Why would you want to (legally) export a PME?
     
  5. wklivesvtime

    wklivesvtime New Member

    Because of the differing resistivity of the materials than make up the earths crust. Supp bonding should solve this no, or if you spike your pme at the outbuilding it would provide a local path for the local fault?
    Thinking to truly export pme you would spike the n at the outbuilding terminate all your earths to the n core of the incoming supply to that building. This is a no no i no :) but it is basically extending your supply system. I think in sines origional post the rod serves little purpose
     
  6. Lokkars Daisy

    Lokkars Daisy New Member

    The term Exporting PMEis used frequently , it often as not just means running a L N &E to an out building ,must agree the term is misleading
     
  7. jimmythemap

    jimmythemap New Member

    Good point well made Mr Sine, hats off

    PME into house then TN-S to everything else with a back up ROD in case of Earth failure anywhere else on system..

    Like having the handbrake in case the brakes fail really...

    Q. Would this not create some sort of TN-C System within the consumers zone etc ?
     
  8. wklivesvtime

    wklivesvtime New Member

    only if you start using your n as a conductor intended to carry fault current within the cus install, sines origional post does not suggest this. It is a no no as our rule book is different to dno and 7671 forbids it bogo domestic install. Tnc systems have to fill certain criteria of which i am not sure
     
  9. Reg Book

    Reg Book New Member

    Exacto mondo LD

    Take the L N &E to the outbuilding comply with the regs on combining the CPC and main bonding conductor and hey presto - no problemo

    Use SWA as protection - bond the armour in case of fault.

    Earth spike if as the designer you decide that the installation warrants it - I would suggest not a shed, but a farm outbuilding yes...:)
     
  10. Lokkars Daisy

    Lokkars Daisy New Member

    Ignoring Sines earth rod for the moment.
    The usual excuse for not running a cable from a pme supply using the pme earth is a possible difference between true earth and pme earth, the reason being
    I'll paste it's quicker

    A voltage difference may exist, under normal conditions, between the PME earthing terminal at the origin of an installation and ‘true’ Earth potential, depending on the distribution network configuration and loading. This is due to the voltage drop caused by the load current returning to the source through the PEN conductor, which has a certain impedance. The voltage above Earth potential could, under certain conditions (such as reduced body resistance due to the presence of water), create the possibility of perceived shock for a person simultaneously in contact with an exposed-conductive-part or an extraneous-conductive-part and ‘Earth potential’

    Now no one is at all concerned about the pme supply to my house ,and that I might experience something nasty between my pme earth and true earth.

    Is that because the dno have installed an earth rod just outside my house, so limiting the pd .I think not ,but I don't know ,where is my earth rod ?

    And so why all the fuss about supplying an outbuilding ,why do a many of you insist on making an outbuilding TT ??
     
  11. X

    X New Member

    In short...

    The PME into your house is beyond our control.. if it goes wrong then its their problem, and any claims are against them.

    If however we install a supply to an outbuilding then its us with whom the buck stops if there is a problem..

    TT with its rod and rcd's is as good as it gets when your not in the national electricty supply business.
     
  12. DandMElectrical

    DandMElectrical New Member

    5 pages of discussion over what exactly ?

    As long as the remote services can be bonded what is the whole song and dance about ?

    If you cant reliably bond all extraneous conductive parts adopt a tt system.

    I fail to see why you are all getting so excited over nothing.
     
  13. JP.

    JP. Screwfix Select

    *

    [Edited by: forum admin]
     
  14. wklivesvtime

    wklivesvtime New Member

    no ones geting excited dm just been chewing the fat on this one thats all. Angry jp?
     
  15. Clark Kent

    Clark Kent New Member

    5 pages of discussion over what exactly ?

    As long as the remote services can be bonded what is
    the whole song and dance about ?

    If you cant reliably bond all extraneous conductive
    parts adopt a tt system.

    I fail to see why you are all getting so excited over
    nothing.




    Your entitled to your opinion, I suppose..
     
  16. 2 wheeled ant

    2 wheeled ant New Member

    Still think its a great idea, what we need is a regulation evoked so we have to do it! each time

    10mm price will drop & rods etc
    plus you only need to stock 1 size! ideal

    Ant
     
  17. sparkin!

    sparkin! New Member

    To the pathetic ***** who have never had the balls to ever post something in full view of the Forum and can only see there own trumped methods..you are all self opiniated assoles incapable of seeing the wood for the trees
    REALLY, Boy!
    I questioned the b* **!
    YOU, didn,t?????

    [Edited by: admin5]
     
  18. 2 wheeled ant

    2 wheeled ant New Member

    ???? What???? i say again what????

    Ant
     
  19. sparkin!

    sparkin! New Member

    HANG, on, what?
    ITS, still a tns/pme?
     
  20. DandMElectrical

    DandMElectrical New Member

    Why are you putting in an earth rod in the remote building when the exported earth and subsequent bonding of extraneous services will provide a suitable earth without augmentation from a rod ?
     

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