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 52 replies
  • Subscribers 30 subscribers
  • Views 11000 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

Extra Low Voltage (ELV)

Former Community Member
Former Community Member
Guys,


BS7671:2018 is classing cables extra low voltage (ELV) as an operating voltage not exceeding 50Vac or 120V ripple-free dc.


BS7671 goes on to further categorize ELV cables into SELV, PELV, FELV.


For single core green/yellow insulated equipotential bonding cables lets say originating from an earth bar and bonding some structural steel work, are these classed as FELV under BS7671:2018 ?
Parents
  • Former Community Member
    0 Former Community Member

    AJJewsbury:




    So the circuit protective conductor or any other protective conductor has to be capable of withstanding the voltage and current that may be placed on it, which in the case of a FELV circuit is generally 240 volts, even though the circuit is rated at say 24 Vdc.



    I'm not sure I understand the concept of a protective conductor being able to "withstand" a certain voltage - given that generally there's no requirement for protective conductors (or they parts they connect) to be insulated. Live conductors need insulation of course (including from the protective conductor or exposed-conductive-parts) - and in the case of FELV that might need to be according to the voltage of the primary circuit rather than the secondary - but I'm not aware of any similar requirement for FELV c.p.c.s.


       - Andy,

     




    Andy in my opinion I would agree and I would say the current is the relevant factor. For example we frequently use a 10mm2 bare un-insulated aluminium cable/tape under BS EN/IEC 62305 to conduct millions of volts safely to ground during a strike.

Reply
  • Former Community Member
    0 Former Community Member

    AJJewsbury:




    So the circuit protective conductor or any other protective conductor has to be capable of withstanding the voltage and current that may be placed on it, which in the case of a FELV circuit is generally 240 volts, even though the circuit is rated at say 24 Vdc.



    I'm not sure I understand the concept of a protective conductor being able to "withstand" a certain voltage - given that generally there's no requirement for protective conductors (or they parts they connect) to be insulated. Live conductors need insulation of course (including from the protective conductor or exposed-conductive-parts) - and in the case of FELV that might need to be according to the voltage of the primary circuit rather than the secondary - but I'm not aware of any similar requirement for FELV c.p.c.s.


       - Andy,

     




    Andy in my opinion I would agree and I would say the current is the relevant factor. For example we frequently use a 10mm2 bare un-insulated aluminium cable/tape under BS EN/IEC 62305 to conduct millions of volts safely to ground during a strike.

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