Electric switch terminology - gangs and ways

Redlander

I'm planning on getting the house rewired and I need to be sure of the terminology. I get that gangs are the number of switches on a plate, and ways are the number of locations a light can be controlled from.
However there's one switch I'm not sure how to describe. It's a 2 gang switch and each of the 2 lights that it controls can be controlled by one other switch. So is it 2 gang 2 way, 2 gang 4 way, or even perhaps 2 gang 3 way?

bjorn_toby_wilde

2 gang 2 way

bjorn_toby_wilde

So, at the bottom of the stairs in my son’s house there’s a switch. One gang operates the lounge light, which is also controlled from a switch on the far side of the lounge.

The other gang operates the landing light, which is also controlled from a switch on the landing.

This switch is 2 gang, 2 way.  The other two are 1 gang 2 way.

Hope that makes it clearer.

bjorn_toby_wilde

Also worth mentioning, if you’re making a shopping list, that you’ll need 3 core and earth cable to wire between the switches.

Wish I’d typed that all into one message now 🤣

Section62

Redlander said:

I'm planning on getting the house rewired and I need to be sure of the terminology. I get that gangs are the number of switches on a plate, and ways are the number of locations a light can be controlled from.

If you are talking about the lightswitch then 'ways' is the number of (connected) positions the switch can be in.  1-way = simple on/off.  2-way = 'common' terminal connected to either terminal 1 or to terminal 2.  3-way switches (and higher) exist, but you won't normally find them used in domestic mains lighting.

If a light is switched from more than one location then that might be referred to as being 'switched 2-way' or 'switched 3-way'.  But 3-way switching of a light usually involves 2x 2-way switches plus a special 'intermediate' switch.  More than one 'intermediate' switch can be used to increase the number of switching locations. E.g. 2x 2-way plus 2x intermediate would be used to give you 4 switching locations.

ic

Whilst rewiring, make sure your electrician runs you neutrals to the switch too - this gives you the option to use smart switches in the future.

Redlander

Thanks, everybody. but there's one thing I'm still unclear about. How would you describe a switch that has two gangs, one of which is 2-way and the other 1-way? Or does such a configuration never exist?

Section62

Redlander said:

Thanks, everybody. but there's one thing I'm still unclear about. How would you describe a switch that has two gangs, one of which is 2-way and the other 1-way? Or does such a configuration never exist?

Usually you use a 2-gang 2-way switch and only connect one of the ways on one of the gangs.  The manufacturing cost difference between a 1-way and 2-way switch is marginal (1-gang 2-way (1G2W) are sometimes cheaper than 1G1W) so to manufacture and stock a 2W+1W switch would probably be more than the extra cost of making a 2G2W.

bjorn_toby_wilde

Redlander said:

Thanks, everybody. but there's one thing I'm still unclear about. How would you describe a switch that has two gangs, one of which is 2-way and the other 1-way? Or does such a configuration never exist?

I don’t think it does exist. You would just use a 2 gang 2 way and wire one of the gangs as a one way switch.  Use either L1 or L2 for the switched live.

Alanp

ic said:

Whilst rewiring, make sure your electrician runs you neutrals to the switch too - this gives you the option to use smart switches in the future.

That’s interesting, when I was a sparky many, many years ago, we used to use the loop in system where everything was done through the lights, I work in a care home that is undergoing a refurbishment and the electrician’s are wiring everything to the light switches, 

WIAWSNB

Alanp said:

ic said:

Whilst rewiring, make sure your electrician runs you neutrals to the switch too - this gives you the option to use smart switches in the future.

That’s interesting, when I was a sparky many, many years ago, we used to use the loop in system where everything was done through the lights, I work in a care home that is undergoing a refurbishment and the electrician’s are wiring everything to the light switches, 

I did the wiring for our loft conversion a good decade ago, and decided to use that method as there were just 4 lights. A couple of JBs supplied the 1mm cable to each light switch, and hence off to their light fittings. The 'live' was cut in the switch box, and the switch inserted. Soooo much easier to wire, and also provided the option of upgrading to Smart as IC says (tho' I wasn't aware at the time...). It also means there isn't a permanent live at the light fitting. 
I'm not saying it's the way to do it - there must be pros and cons? - but it'll be interesting to hear which method the sparkies you get to quote will use. Please feed back. 
To add to the explanation of switch types above if still needed, yes 'gang' is the number of physical switches on the plate. If you want one switch plate to operate 3 different lights, you fit a 3 gang switch. A one-gang is often referred to as a 'single', 2 a double, 3 a triple...
'Ways' are literally the number of ways the switch can send the switched power out - for most, it'll be 'one-way', Ie one switch will control one light. If you look at 99.99% of (one-gang or 'single') light switches, you'll find it either has two terminals or three. 
A two-terminal, one-way switch should be self-explanatory; one is usually marked 'common' or 'COM', and the other usually 'L1'. Convention says the Live should go to COM, and L1 then takes the switched power to the light fitting. It will work exactly the same if wired the other way around - all that's inside the switch is a springy metal strip that's pushed into contact with the other terminal - but you'll break 'convention'.
If your single switch has three terminals - and many will - then it'll technically be a 2-way jobbie, but can still be used as the one-way switch above - to turn one light on and off.
A 2-way switch will have the same COM and L1, but also an L2. To wire it for switching one light on and off, use COM and L1 as before. (Or, use L2, but the switch will work upside down, like in the yoo-ess!)
With a two-way switch, the COM will connect with L1 with the switch in one position, and L2 in the other.
BOTH L1 and L2 are used (with '3-core' + e wire) for two-way lighting situations, such as having one switch at one end of a hallway, and another at the far end, but both controlling the same light. 
With a normal single switch, you'll know that 'up' is off and 'down' is on' (opp of US) , but with two-way switches, this will change depending on the other switch. I'm sure you've noticed this before - I'm in the granny-suck-egg territory here.
And that pretty much leaves one other type of switch - the 'Intermediate' switch. This is if you want three - or more - separate switches controlling a single light(s). Where would you want this? Perhaps in a long hallway with one switch as you come in the front door, one switch half way down the hall as you enter the sitting room, and a third switch further along the hallway where the staircase is. 
So, you come in the front door, turn the hallway light on, walk to the sitting room and turn it off before going in. Someone comes down the stairs and turns it on at the far hallway end, and off again when they enter the sitting room - or exit the house. All three switches will look to be in random positions, either up or down - that doesn't matter.
So, these are the ways of switches. You then add 'gangs' as you want - each one is a different circuit, controlling different lights.
All you need to do is to sit down and work out how many lights you want in each room, ceiling or wall or both, how you want them switched - one or two way or a combination - and that will determine the number of 'gangs'. And then if there's any situation that may require an intermediate switch.
Then on a plan of yer hoosie, mark these out; Sitting room - 2-gang switch at this door, both dimmer type suitable for LED, one of 2-way for the ceiling light with other 2-way at patio door, and other controlling both wall lights. Summat like that.
One more detail - you cannot have two dimmers on the same 2-way circuit. Say your sitting room has a 2-way ceiling light, one switch as you come in the room, and another at the patio doors (so you can turn on the ceiling light whichever way you come in or leave the room), and you want it dimmable, then one switch would be the dimmer, and the other a normal on/off. So only one can control the brightness - you'd make that the one you'd expect to use most, I guess.
The only way around this afaIk, is to use Smart controls, but that's not summat I'm familiar with. 
One more thing - if any guests outstay their welcome at Chrimbo, read the above out aloud. 
Happy Chrimbo.