We get a quite a few visitors from the U.S. so just for our friends over the pond, here is a lighting circuit site just for you, with lots of great diagrams, enjoy: U.S. lighwinging circuit diagrams
Here is a two way switching solution posted for one of our users who had run the power feed to one of the switch boxes and had no radial circuit to pick up a neutral at the lamp holder.
The ceiling rose, sometimes called a ‘loop-in ceiling rose’ or ‘3 plate ceiling rose’ is effectively a junction box for the power feed, switch wire and pendant flex of a ceiling light:
The ceiling rose has 3 sets of discreet terminals for the current carrying conductors plus an additional terminal for terminating the earthing conductors.
The diagram below shows the terminals in the ceiling rose plus typical termination of the cables:
We have just added the light wiring diagram for two way switching in the old cable colours, you can find it here:
You’ll also find the light wiring diagram for 3 way switching in the old cable colours here:
If you are searching online for 2 way switches/switching and 3 way stitches/switching the results can be very confusing to the layman depending on wether you land on a US or UK website. This is because the terminology used is very different.
This site follows UK usage. So for the benefit UK visitors searching online and American visitors to this site, hopefully the following will help to clarify:
UK – So, this (Fig 1) is what we call a 2 way switch: when you switch it one ‘way’ (on or position 1) the COM terminal is connected to the L1 terminal. When you switch it the other ‘way’ (off or position 2) the COM terminal connects to the L2 terminal.
If you are describing this switch to an electrician or electrical supplier you should refer to it as a 1 gang 2 way light switch and they will know exactly what you mean (see gangs and ways).
US – Strangely, our friends across the pond refer to this switch as a 3 way switch because it has 3 terminals.
Generic – if you asked someone in the field of electronics, they would probably describe this switch as a Single-pole, Double-Throw (SPDT) switch, to my mind a more useful description as this means the same in UK and US. A good electrician would understand this terminology but they, historically, rarely use it.
UK – so, this (Fig 2) is what we call an intermediate switch, so called because it is used ‘in between’ two x 2 way switches to achieve 3 way switching (clarified below under multiway switching). Sometimes called a crossover switch for obvious reasons.
If you are describing this switch to an electrician or electrical supplier you should refer to it as a 1 gang intermediate light switch and they will know exactly what you mean.
US – in America they refer to this switch as a 4 way switch because it has 4 terminals.
Generic – Double-pole, Double Throw (DPDT) switch.
Now we understand the different terminology used for the actual switches it is easy to appreciate why different switching arrangements are referred to using different terminology also.
Scenario 1: we have 1 light that can be turned on and off from two different light switches:-
UK – we would call this 2 way switching. Why? well a layman probably uses this terminology because 2 switches are used, whereas an electrician because two 2 way switches are used to achieve this. Either way, we are both referring to the same thing.
US – This would be referred to as 3 way switching because its uses what they would refer to a two 3 way switches.
Scenario 2: we have 1 light that can be turned on and off from three different light switches:-
UK – we would call this 3 way switching, well a layman certainly would (because of the three switches) and an electrician would assume this is what is meant but may also refer to it as 2 way plus intermediate switching.
US – This would be referred to as 4 way switching because it utilises what they refer to as a 4 way switch (what we in the UK call an intermediate or crossover).
We have just added additional circuit diagrams to the two way switching page.
This particular page shows two way switching in the old cable colours linking to a looped radial circuit that uses ceiling roses. As some older houses with these old cable colours may have looped radial circuits utilising junction boxes we have added an additionl circuit diagram that shows this. Check it out here:
We’ve uploaded new diagrams for three way switching (sometimes referred to as two way switching plus intermediate). so if you plan on doing some house wiring you’ll find Full instructions, schematic diagrams and installation illustrations:
These light circuit diagrams will be of use if you have 3 light switches that control a single light.
If you have the old cable colours you need
3 way switching (old colours)
If you have the new cable colours you need:
3 way switching (new cable colours)
Here we have a 5 amp 4 terminal junction box that is ideal for use in lighting circuits. You will often see these used in old looped radial circuits instead of a ceiling rose in older houses. They are useful for ‘breaking in’ to an existing radial power loop to add additional wall lights in a room for example.
You can use our old friend the choc-block (nasty avoid it) but it will need to be in a suitable enclosure and kept away from anything that may give off heat (the plastic is much softer than the JB above) so you may as well use our friend above for lighting circuits.
No this is not a post about some dodgy Ross Kemp program:) Here we will attempt to clarify a subject that causes much confusion amongst you budding D.I.Y. types…
Single gang 2 way, Triple gang 1 way, 2 gang 1 way, bla-d-bla-de-bla. So what the f**K does it all mean? Panic not my friends, it’s actually quite simple (although you wouldn’t think it if you have been reading many of the popular D.I.Y blogs).
Forget about the ‘WAYS’ first concentrate on the ‘GANGS’
So, just think of a gang as a single switch, simple as. If your light switch has one ‘switch button’ on it then it’s a single (or 1) gang switch. If it has two ‘switch buttons’ on it then it’s a double (or 2) gang switch. etc. etc.
‘GANGS’ are easy, so what of their ‘WAYS’
Well, as far as light switches (or gangs) are concerned, they can only be one of two things; a one way switch or a two way switch, end of.
A one way switch has two terminals, its the simplest of switch arrangements. it’s either on or off, thats all it does. When it’s ‘ON’ the COM terminal is connected to the L1 terminal (let there be light!). When it’s ‘OFF’ the COM terminal is connected to nothing and (the switch is open) no current flows through the switch.
A two way switch has three terminals its a little more complicated (any useful) than it’s one way cousin. When it’s ‘ON’ (position 1) the COM terminal is connected to the L1 terminal. But when it’s ‘OFF’ (position 2) the current is diverted from the L1 to the L2 terminal. This is what we use in circuits when we want to be able to switch a single light on and off from two different switches (see the two way switching lighting diagrams).
So, by way of a little revision
If we have a switch with one “switch button’ (1 gang) it can have a switch mechanism that is either one or two ‘WAYS’ so we have two possible options;
1/ A single GANG one WAY switch or
2/ A single gang two WAY switch
If we have a switch with two “switch buttons’ (2 gangs) it can have a switch mechanism that is either one or two ‘WAYS’ so we have two possible options;
1/ A Double GANG one WAY switch or
2/ A Double gang two WAY switch
There are two terminals in a one way light switch. When the switch is on, both terminals are connected together.
Typically, these terminals will be marked COM and L1 (sometimes L1 and L2). Although, technically, it doesn’t matter which way round you connect the wires, it is best to stick to convention and connect the permanemt live (from the supply) to COM and the switched live (to the lamp) to L1.
This is the most common type of switch, and is used where a light is controlled from a single switch (although you will often see a two way switch used, with one terminal left unused).
This is fairly obvious, but when the switch is ‘on’ the COM and L1 terminals are connected together. When ‘off’ they are not.