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 14 replies
  • Subscribers 32 subscribers
  • Views 5353 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

Switched neutral

Harry Macdonald
Looking at the BS7671 AMD2 out for consultation, I noticed clause 463.1.2. This shows an arrangement whereby the control device for a lighting circuit is switched by a switch on the neutral side of the device.

Clearly this works but why would anyone want to do this?
Parents
  • 0
    Why? Surely it's safer only to have a single source of supply, than provide a separately switched line, given your argument?


    Especially true in TN systems where isolation of the Neutral is not necessary. Also, better to ensure the circuit can be isolated from a single point of isolation, because there's nothing in BS 7671 to mandate that the coil is supplied (through the light switch) from the same points of isolation as the switched line through the contactor ... which is why we end up with fan isolators with the extra pole for switched line.
Reply
  • 0
    Why? Surely it's safer only to have a single source of supply, than provide a separately switched line, given your argument?


    Especially true in TN systems where isolation of the Neutral is not necessary. Also, better to ensure the circuit can be isolated from a single point of isolation, because there's nothing in BS 7671 to mandate that the coil is supplied (through the light switch) from the same points of isolation as the switched line through the contactor ... which is why we end up with fan isolators with the extra pole for switched line.
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