Discuss Wiring a switch in a light circuit in the Electrical Courses & Electrical NVQ's area at ElectriciansForums.net

Kuba Starzynski

Trainee Access
Messages
7
Location
London
Hi everyone, I hope someone here can shed some light on this for me please,


I have come across two forms of wiring 2 way switches. I understand the basics behind these, first one with live coming from the light and switched live going back, second using same rule but in com instead of l1 and l2 (strappers in same position).
I guess the question is which one to choose in what circumstances?
Is it based on the location of the switch/light - using least amount of cable when possible or,
Depending on light if it's 3 plate or 2 plate?
I would like to understand it from someone's point of view who's in the trade.

Also, is this correct that in case of 2 plate light wiring you have to bring a t&e to a switch and terminate neutral there?

Finally, last question -


If this was wired in the other form with live going to com from the supply and switched live going from the last com back to the light, you wouldn't have to use a strapper between two coms because that would make it permanent live?

Thanks for help!
 

robd

Electrician's Arms
Messages
555
Location
East Anglia
Yes it does depend on which uses the least cable a lot of the time. Like you said you can 3 plate the light or the switch, personally I often prefer to do it at the switch as it's easier to terminate there and if you have a light fitting to put up later it's a lot easier with l,n & e there than 3 plate. You might get someone tell you that 3 plating at the switch is not the way to do it but that's tosh in my opinion so long as you have enough room to terminate at the switch, nothing is squashed and it's all neat then it's just as good. In regard to your understanding of switching all I can say is draw them out and you should be able to suss out any arrangement I had a little pocket book when I was an apprentice and if I ever got stuck I would either refer to it or draw it out. Everyone learns in their own way but once you have it straight in your head it's like riding a bike
 

Tony Reidy

Electrician's Arms
Messages
118
Location
bedfordshire
Hi everyone, I hope someone here can shed some light on this for me please,


I have come across two forms of wiring 2 way switches. I understand the basics behind these, first one with live coming from the light and switched live going back, second using same rule but in com instead of l1 and l2 (strappers in same position).
I guess the question is which one to choose in what circumstances?
Is it based on the location of the switch/light - using least amount of cable when possible or,
Depending on light if it's 3 plate or 2 plate?
I would like to understand it from someone's point of view who's in the trade.

Also, is this correct that in case of 2 plate light wiring you have to bring a t&e to a switch and terminate neutral there?

Finally, last question -


If this was wired in the other form with live going to com from the supply and switched live going from the last com back to the light, you wouldn't have to use a strapper between two coms because that would make it permanent live?

Thanks for help!
3 core and earth best way avoiding the possibility of a borrowed neutral
 

chris gray

Electrician's Arms
Messages
845
Location
east riding of yorkshire
I always take my feed to my switches. Take a 3c&e between switches for strappers and neutral, then take sw upto light from 2nd switch.
Like what’s been said, each to their own.
Personally I built a full test rig at home and turned theory into practice on it.
 

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