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 21 replies
  • Subscribers 29 subscribers
  • Views 1725 views
  • Users 0 members are here
Options
You may also be interested in
This discussion is locked.
You cannot post a reply to this discussion. If you have a question start a new discussion

An interesting issue with a TT supply

Alan Capon
An interesting real life example of why you need double pole switching with a TT supply. The scenario is a small village with a few customers supplied by a single pole mounted transformer. 


We got a call from an electrician working in a property who had measured 400V phase to earth, 210V neutral to earth, and 241V phase to neutral, and was understandably worried. Any suggestions of what I tracked the fault down as? This can happen on any TT supply, but is fortunately very rare - I have come across it three times in 20 years. 


Regards,


Alan.
Parents
  • 0
    There are plenty of three phase PMTs around.  Smaller PMTs tend to be single or split phase.  Generally up to 100kVA on a single pole and up to 200kVA on either an H pole or pole with a stub pole, Tf sits on steelwork between the two..  I have seen bigger than 200kVA but not very often.  IIRC pole mounted substations are exempt from business rates which I think are charged on ground mounted.
Reply
  • 0
    There are plenty of three phase PMTs around.  Smaller PMTs tend to be single or split phase.  Generally up to 100kVA on a single pole and up to 200kVA on either an H pole or pole with a stub pole, Tf sits on steelwork between the two..  I have seen bigger than 200kVA but not very often.  IIRC pole mounted substations are exempt from business rates which I think are charged on ground mounted.
Children
No Data

Join us to get the best from IET EngX.

Joining EngX lets you personalise your experience so you stay up to date on the topics that interest you, plus you’ll be able to make connections who are looking to collaborate, exchange ideas and more.

Join us Not now

Community Rules & Guidelines