With a pair of 3 way switches either can make or break the connection that completes the circuit to the light.
2 way light switch wiring diagram old colours.
You have an incoming hot wire black going to one screw it does not matter if you use the brass or silver screw on the side of the 2 way switch and a black wire from the other screw on the 2 way switch going to the load light ceiling fan etc.
Wiring a 3 way light switch is certainly more complicated than that of the more common single pole switch but you can figure it out if you follow our 3 way switch wiring diagram.
The power source comes from the fixture and then connects to the power terminal.
Two very old three way switches are depicted in the photo above.
Your lighting circuit must.
3 way light switching new cable colours 3 way light switch old cable colours 3 way light switch using a two wire control.
Notice the black wire is the only wire that we are controlling through the 2 way switch.
Schematic diagram of new wire colours.
The switch wiring is all the same but the switch wire cable c leads up to a different set up.
You will see that there is a hot wire that is then spliced through a switch and that then goes to the hot terminal of the light.
There is a chance that if your house has these old wiring colours the switch drops may be from a loop in loop out radial lighting circuit done with junction boxes rather than ceiling roses as shown in fig 2.
Two very old three way switches.
3 way switch schematic wiring diagram.
A two way switch uk schematic diagram of old wire colours.
The source is at sw1 and 2 wire cable runs from there to the fixtures.
Two way light switching 3 wire system new harmonised cable colours note.
This diagram illustrates wiring for one switch to control 2 or more lights.
A 2 way switch wiring diagram with power feed from the switch light.
The switch wiring is all the same but the switch wire cable c leads up to a different set up.
The hot and neutral terminals on each fixture are spliced with a pigtail to the circuit wires which then continue on to the next light.
The grey wire in cable d is a switched live and the blue wire in cable c and black wire in cable d are permanent lives and thus should be marked with brown sheathing at each end as shown.
Wiring a 3 way light switch.
Multiple light wiring diagram.
For simplicity the earth wire is not shown in the above diagram.
The way i show allows you to fairly easily add a second two way switch to an existing light switch by simply wiring them together in a certain way.
2 way light switch 3 wire system new harmonised cable colours 2 way switch 3 wire system old cable colours 2 way switch two wire control three way switching.