The IET is carrying out some important updates between 17-30 April and all of our websites will be view only. For more information, read this Announcement

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

  • State Helpful Answer
  • Replies 26 replies
  • Subscribers 38 subscribers
  • Views 720 views
  • Users 0 members are here
Options
You may also be interested in

Is the UK the only country that continues to permit and deploy TN-C-S earthing systems?

Philip Oakley

In a discussion about Diverted Neutral Currents, an contributor (Australia I think) suggested that the problem was that it (DNC) is unique to UK.

I'm not that well versed in international systems of earthing, but it's my understanding that while part of the diverted neutral current problem is because of PME (Protective Multiple Earth), and PEN (Protective Earth and Neutral). And that the the problem is likely to be common to all systems, because there is only one planet earth/ground and we all have to be careful with it when latent and patent faults abound.

I suspect part of the issue is that different folks hear different parts of the story and then project the aspect that's different from their system onto the UK system (given we are reporting it).

Is PME / TN-C-S special to UK?

(discussion was in a Youtube video on ' Loose Neutral Fault Explained')

 

Parents
  • +1
    Philip Oakley said:
    an contributor (Australia I think) suggested that the problem was that it (DNC) is unique to UK

    PME, or more broadly TN-C-S (i.e. TN-C distribution network, separated out at the consumer service head) is NOT unique to the UK, although in some countries other acronyms are used. Examples include (but may not be limited to, and in no real order):

    • Australia (where it is called MEN - multiple earthed neutral)
    • New Zealand (also called MEN)
    • Republic of Ireland (termed TN-C-S)
    • South Africa
    • Germany
    • Austria
    • Netherlands
    • Norway (just starting to use the arrangement)
    • USA (called MGN - multiple grounded neutral)
    • Canada

    I would be really surprised if someone in Australia believes diverted neutral currents (and open-circuit or high resistance neutrals) in TN-C-S systems are unique to the UK, because I understand there have been a number of cases in Australia, among the most serious being a very sad and widely publicised case of severe electric shock received by a child in 2018 as a result of a broken MEN neutral: www.wa.gov.au/.../Investigator-releases-report-into-electric-shock-of-Denishar-Woods-20190927

    In the USA, diverted neutral currents are known to be problematic, and there have been reported cases of diverted neutral currents in and around marinas etc. that might have been responsible for cases of electric shock that resulted in drowning.

  • 0 in reply to gkenyon

    Thank you Graham.

    Reading between the lines of the correspondents replies, it sounds like the supplies they work on have the MET supplied by their electric supplier, so a slight shift across the interface responsibilities between arrangements.

    I'm also guessing that there is a lot of well distributed (distance between) supplies in their Au context, while many of our DNCs are either cluttered or old supplies. Experiences vary.

    Thanks again for the clarifications.

  • 0 in reply to gkenyon

    Unfortunately the report itself appears to have gone awol.

    Another page https://www.wa.gov.au/government/announcements/release-of-beldon-electrical-accident-report shows the WA method of connection being discussed, with the MET being on the DNO side, and no DNO side CPC (i.e. only a 2-wire supply).

Reply Children
  • 0 in reply to Philip Oakley
    Philip Oakley said:
    shows the WA method of connection being discussed, with the MET being on the DNO side, and no DNO side CPC (i.e. only a 2-wire supply).

    In the UK, the distributor provides the TN-C-S earthing terminal.

    In other countries, it is not always the case, and the consumer takes the neutral and separates the supply.

    At the end of the day, it's all TN-C-S, and the same risks apply, regardless of where the legal fault might be, and where the "-S split" occurs.

  • 0 in reply to Philip Oakley

    I've put in an enquiry to the WA govt (email and contact form) to request a copy of the report and asking that their web interface correct the link errors.

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