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

  • State Suggested Answer
  • Replies 9 replies
  • Helpful Answers 1 Helpful answer
  • Subscribers 39 subscribers
  • Views 1704 views
  • Users 0 members are here
Options
You may also be interested in

How big does a 3 phase in-balance need to be to mask an open pen fault

Alan B

This is looking at the previous project I was  discussing with two EVCP's on two phases of a 3 phase supply.
Just realised that I may have issues relying on single phase voltage based open pen detection when connecting to a 3 phase supply.


AI says Regulation 722.411.4.1(iv) of BS 7671:2018+A1:2020 prohibits the use of a protection device for open-PEN (Protective Earth and Neutral) detection in single-phase EV charging points supplied by a three-phase installation. This is because this specific type of open-PEN protection is designed for single-phase installations only, and a three-phase supply has different electrical characteristics that are not compatible with this protective measure. 

Looking at amendment 2 I can't see this wording, am I just missing it, or has it been removed?


Parents
  • 0

    White check mark Regulation 722.411.4.1 Breakdown (Amendment 2, 2022)

    BS 7671 doesn’t ban open-PEN protection on 3-phase supplies. It provides multiple compliant methods under 722.411.4.1:

    1. Clause (i) – The EV point is part of a balanced 3-phase installation; fault voltage remains ≤70 V rms.
    2. Clause (ii) – An earth electrode limits voltage to ≤70 V rms during PEN loss.
    3. Clause (iii) – A detection/protection device monitors CPC vs. earth (or derived reference) and disconnects if >70 V rms.
    4. Clause (iv) – A device for single-phase circuits with similar functionality.
    5. Clause (v) – Alternative equivalent methods meeting requirements (iii) or (iv). 

    Pushpin Key Point

    724.411.4.1 does not ban open-PEN detection in three-phase systems—it merely requires the correct detection/protection device. There's no blanket prohibition, and the wording has not been removed—it's clear in Amendment 2.

    Wrench Best Practice

    • Use a proper open-PEN detection device (e.g., O-PEN) for 3-phase PME systems.
    • Ensure any detection monitors CPC-to-earth or derived references and triggers isolation when >70 V for >5 s. 
    • Avoid relying solely on single-phase voltage monitoring without device compliance under (i) to (v).
  • 0 in reply to Mohammad Junaid Khan

    Ensure any detection monitors CPC-to-earth or derived references and triggers isolation when >70 V for >5 s. 

    But that's exactly the original problem - devices that come under (iv) (or possibly (v)) don't work like that - but rather monitor the L-N voltage, which can give rather different results - worst case c.p.c.-Earth could be anything up to 128V indefinitely and still not trigger a disconnection.

    While BS 7671 gives minimum acceptable standards, it shouldn't be beyond the designer to understand the implications of all the available options and choosing the best (or at least worst) for their particular situation.

    You might find IET 01 of interest ... electrical.theiet.org/.../

       - Andy.

Reply
  • 0 in reply to Mohammad Junaid Khan

    Ensure any detection monitors CPC-to-earth or derived references and triggers isolation when >70 V for >5 s. 

    But that's exactly the original problem - devices that come under (iv) (or possibly (v)) don't work like that - but rather monitor the L-N voltage, which can give rather different results - worst case c.p.c.-Earth could be anything up to 128V indefinitely and still not trigger a disconnection.

    While BS 7671 gives minimum acceptable standards, it shouldn't be beyond the designer to understand the implications of all the available options and choosing the best (or at least worst) for their particular situation.

    You might find IET 01 of interest ... electrical.theiet.org/.../

       - Andy.

Children
No Data

Community Rules & Guidelines