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Discuss Three Phase overhead supply is it TN C in the Periodic Inspection Reporting & Certification area at ElectrciansForums.co.uk.

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  1. Michael J
    Offline

    Michael J Michael J

    Location:
    Swansea
    While carrying out a EICR I found on first inspection that there were no RCDs installed . When I checked at the Pole Mounted Transformer the Earth & Neutral were connected at the Neutral point. So am I right in concluding it's a TN-C System? The 17th Edition states that RCDs should not be installed where a TN C System is used (411.4.4)
     
  2. buzzlightyear
    Offline

    buzzlightyear still kicking sand, before pushing up daisies . Electrician's Arms

    Location:
    star command
    Are you sure it is tncs on the pole or TT.what is in the property?.
    got any pic of the board .
     
  3. Michael J
    Offline

    Michael J Michael J

    Location:
    Swansea
    I will take a pic tomorrow,but it looks like the Earth and Neutral are connected at the transfer. The reason I am suspecting is a TN-C is the lack of RCD protection on the Ring main final circuits. If it was a TT it would be protected with RCD at the mains
     
  4. buzzlightyear
    Offline

    buzzlightyear still kicking sand, before pushing up daisies . Electrician's Arms

    Location:
    star command
    you mean up front RcD Before the main switch .
     
  5. Michael J
    Offline

    Michael J Michael J

    Location:
    Swansea
    Yes, or any final circuit in the building, by the way it feeds a hotel. The overhead feed is by way of bundle conductors (4) sorry that's a South African term. I don't know what you call them here?
     
  6. buzzlightyear
    Offline

    buzzlightyear still kicking sand, before pushing up daisies . Electrician's Arms

    Location:
    star command
    is it three phase to the buiding.
     
  7. Archy Styrigg
    Offline

    Archy Styrigg Electrician's Arms

    Location:
    Manchester
    Eh?
    The 17th Edition states that RCDs should not be installed where a TN C System is used 411.4.4

    The following types of protective device may be used for fault protection:
    (i) An overcurrent protective device
    (ii) An RCD.

    It'll be a PME supply. Concentric cable split at the installation intake, to N & E.
     
  8. Michael J
    Offline

    Michael J Michael J

    Location:
    Swansea
    Read on a couple of lines after Note 1
    "An RCD Shat be used in a TN-C system"
     
    • Funny Funny x 1
  9. Michael J
    Offline

    Michael J Michael J

    Location:
    Swansea
    Sorry guys it's late it should read " An RCD Shall not be used in a TN_C system":oops:
     
    • Funny Funny x 1
  10. Michael J
    Offline

    Michael J Michael J

    Location:
    Swansea
    Yes it is
     
  11. Archy Styrigg
    Offline

    Archy Styrigg Electrician's Arms

    Location:
    Manchester
    I think you might be getting confused here chief, TNC is NOT allowed within an installation. TNC/PME supply, then the Earth is split off at the intake.
     
  12. Strima
    Offline

    Strima Electrician's Arms

    Location:
    St Neots
    That'll be 414.4.5 for no RCD on TN-C?
     
    • Agree Agree x 1
  13. buzzlightyear
    Offline

    buzzlightyear still kicking sand, before pushing up daisies . Electrician's Arms

    Location:
    star command
    take pic for us in the main intake at the hotel.
     
  14. buzzlightyear
    Offline

    buzzlightyear still kicking sand, before pushing up daisies . Electrician's Arms

    Location:
    star command
    Strima are you not counting sheep in your bed .LoL .because im in night garden with iggle piggle.;)
     
    • Informative Informative x 1
  15. Michael J
    Offline

    Michael J Michael J

    Location:
    Swansea
    Thanks, I will take a closer look at the intake, I just don't understand why there are no RCDs on the final ring circuits this hotel has 6 DBs
     
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