Rules and Guidelines
Want to participate in the discussions? Please read our Community Rules and Guidelines. Need some help? Visit Support and Answers.

  • State Not Answered
  • Locked Locked
  • Replies 16 replies
  • Subscribers 37 subscribers
  • Views 2794 views
  • Users 0 members are here
Options
You may also be interested in
This discussion has been locked.
You can no longer post new replies to this discussion. If you have a question you can start a new discussion

Suburban filling station

lyledunn

This is a new site in a densely populated area. TT 400A TPN DNO supply. The site is pinned to earth by electrodes at various points, several along the wooden perimeter fence you see to the left.

The DNO Tx is immediately behind the metal fence. The whole surrounding area is PME. DNO would obviously not provide a PME terminal but given the proximity of other buildings, is it prudent to consider the site as TT?

Parents
  • 0
    lyledunn said:
    DNO would obviously not provide a PME terminal but given the proximity of other buildings, is it prudent to consider the site as TT?

    I think the answer to this is yes, TT ... but there are some bits of thinking in design of TT systems in urban settings, which are perhaps often overlooked in TT systems in general.

    For example ... we are used to thinking about external earth fault loop impedance being based on the earth electrode path alone, yet with shared extraneous-conductive-parts, or extensive ground-connected metalwork, when the extraneous-conductive-parts are connected, the prospective earth fault current may be substantially higher, perhaps (if there are shared extraneous-conductive-parts with other installations on the same transformer) approaching the L-N prospective fault current.

    There may, similarly, be diverted currents if there are extraneous-conductive-parts shared with other installations. This is obviously not desirable for filling station installations, regardless of whether it's TT or TN-S.

  • 0 in reply to gkenyon

    Also bear in mind this is not a UK location rather ROI.

Reply Children
  • 0 in reply to Gel Jones

    With all this Boris stuff have I missed Northern Ireland’s departure from the U.K.?

Community Rules & Guidelines