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 29 replies
  • Subscribers 32 subscribers
  • Views 2555 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

Regulation for rewring back box?

Former Community Member
Former Community Member

Hi, I'm currently holding an MEng in EEE, but not a certified electrician otherwise. 

I want to install smart light switches in my “dwelling”. I have encountered issues where the current back box is standard 74x74x25, but I would need extend it to 86x86x38 for the new light switch. 

I want check do I need part P certificate, or planning permission? How to be compliant while minimise the cost? (I have no experience in dwelling electrical work)

PS: The dwelling is a new build (2019) 
PPS: I might consider obtain required certificate(s) myself if is not too expensive. Since I like do these kind of work, so it might be cost effective in the long term. 

Parents
  • 0

    Chris Pearson: 

    What you have is T&E used as switched lines, which is why they have brown sleeving. Three way (or four plus) involves crossover switches.

    benforone:

    I think my previous post says my reasoning for thinking the T&E wiring is not used as a switched line. (no borrow). Please correct me if I'm wrong.

    The brown in the T&E at the top is an unswitched line - it comes either from a ceiling rose or junction box. The blue oversleeved in brown is the switched line - that goes  back to the ceiling rose or JB where it is connected to the line of the luminaire. In those diagrams, there is no neutral at any of the switches except the loop-at-the-switch diagram.

    ETA: you appear to have loop-at-the-switch in the example which you show. You would have your two unswitched lines in common, the switched line in L1. Then you need to add a wee bit of blue cable from the neutral block to your smart switch, assuming that it is mains-powered. All the CPCs remain connected to each other and the switch if it is Class I.

    As for abandoning the 2-way cables, I'd keep them rather than chop them off. Ideally all the conductors should be earthed at the supply end.

Reply
  • 0

    Chris Pearson: 

    What you have is T&E used as switched lines, which is why they have brown sleeving. Three way (or four plus) involves crossover switches.

    benforone:

    I think my previous post says my reasoning for thinking the T&E wiring is not used as a switched line. (no borrow). Please correct me if I'm wrong.

    The brown in the T&E at the top is an unswitched line - it comes either from a ceiling rose or junction box. The blue oversleeved in brown is the switched line - that goes  back to the ceiling rose or JB where it is connected to the line of the luminaire. In those diagrams, there is no neutral at any of the switches except the loop-at-the-switch diagram.

    ETA: you appear to have loop-at-the-switch in the example which you show. You would have your two unswitched lines in common, the switched line in L1. Then you need to add a wee bit of blue cable from the neutral block to your smart switch, assuming that it is mains-powered. All the CPCs remain connected to each other and the switch if it is Class I.

    As for abandoning the 2-way cables, I'd keep them rather than chop them off. Ideally all the conductors should be earthed at the supply end.

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