How do I wire 2-way light switches, please? (Ed. )

[aesmith]

Don't they both need at least one connector block for Neutral?

I've seen a third method when the supply comes to the light fitting, with 3 core + earth down to each switch.

 

[ebee]

That depends on where “here” is!

Spot on Taylor lad.
If I might suggest it also depends upon when "here" is too

Much before my time and for a while after I started it was singles or singles and earth that was common, T & E was pretty much considered like a new fangled stuff.
A throw back to those then, not so distant days when metal conduits was the common thing, and boy what artisans of neatly threading cables in conduits those sparkies were.
So, common thinking was singles whichever method of wiring lighting was used.
A three core and earth to convert one way switching to two way switching was a relatively new idea and yes it foxed a few trying to get their head around it.
A simple rule of moving Com conductor to say L2 (leaving say L1 where it was) and the 3C&E terminal to like terminal from 1st to second switch was indeed baffling to many.

 

[EFLImpudence]

Don't they both need at least one connector block for Neutral?

There is not usually a Neutral conductor at the switches.

I've seen a third method when the supply comes to the light fitting, with 3 core + earth down to each switch.

That wouldn't necessarily be another method; just a different route for the cables.


The supply used always to go to the light fitting in the U.K. for both methods.

 

[ebee]

I think all of these alternatives used to be in the Wiki.
So basically, loop in, looping in and joint box.
Also is this done at the ceiling rose or the switch position or even both sometimes.
The two way hamburger. (I must admit I learned of that one no so long ago)
They might even be mixed or hybrids in the same installation.
Take all the variations and tweaks and that is a heck of a lot of possibilities, no wonder folk struggle.
It is, in practice, very unusual to find wiring diagrams or labels to give you a clue.
It`s all part of the rich tapestry of life innit?

 

[ebee]

The supply used always to go to the light fitting in the U.K. for both methods.

I think looping in at switches/neutrals present got more popular for light fittings with small bases and not much room for multiple connections, they might look pretty but can be awkward to align sometimes, if they slightly out of square or walls not running true they can look like they running out by the width or length of a backyard gate.

nice big ceiling roses or big bell like covers makes life easier.

Needless to say I prefers loop in at ceiling rose throughout if possible but I do not suggest that the other alternatives are wrong.

 

[Jurassicspark]

The disadvantage is the large number of wires behind the switch. It may be necessary to use a deeper backbox, and if combined with two or three gang switches, even the deepest backbox may not be enough. I'll go for the loop in at the light fittings or even better by using junction boxes.

 

[ebee]

Yes Handyman quite a good point there

 

[EFLImpudence]

This might help people understand what aesmith had in mind.

Old colours; that's all I had available.

 

[aesmith]

That's exactly what I meant.

And regarding terminal blocks for N, grabbed from another site. And I think if feed and light were connected to the same switch, you'd still need one block to connect N ..

 

[EFLImpudence]

That's exactly what I meant.

And regarding terminal blocks for N, grabbed from another site. And I think if feed and light were connected to the same switch, you'd still need one block to connect N ..

View attachment 321874

Yes, of course, if you did it like that you would need blocks for the neutral.


You do need blocks for the neutrals with loop at switch method (which the diagram is really - without continuing the circuit) and of course one at the light (ceiling rose) for loop at light method with which there are no neutrals at the switches.

 

[ebee]

I think if we imagine the loop in at ceiling rose method where the switchwire is T & E from the rose to a one way switch then substitute that switch drop T & E for 3C&E we can now introduce a N at the switch position whilst already have an N at the rose position.

Similarly for two way we use one 3C&E as the switchwire as described above and the strapper 3C&E from switch 1 to switch 2.

If either or both are 2,3,4 or 6 gang switches then it starts to look even more complicated but does have the benefit of having N at both the rose and the switch positions if needed and whilst it can be technically correct it tends to add another complication for the unwary.

I think this could be what EFLImpudance eluded to a while back.

 

[Deryck Tintagel]

This might help people understand what aesmith had in mind.

Old colours; that's all I had available.

View attachment 321873

This is what I use as convention but I saw a variation in my friend's house where the ceiling rose was used as the connection point for the strappers - i.e. L / SL but the wiring was run in twin and earth so no common visible. Had me foxed for a while until I moved some wiring and found a single an earth used as the COM connected in a terminal block.

 

[aesmith]

The old wiring in our garage/workshop used twin with no earth, plus various single core sheathed cables to provide enough cores. Earthing for the metal switches was provided by a fly lead from the adjacent power point. Where I retained two way switching I replaced the drop cables with three core exactly like EFL showed. Like him I used old colours as that was all I had available.