The switch wiring is all the same but the switch wire cable c leads up to a different set up.
													
																	2 way light switch wiring diagram old colours. 
									
	
		
	
																	The power source comes from the fixture and then connects to the power terminal. 
																	With a pair of 3 way switches either can make or break the connection that completes the circuit to the light. 
																	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. 
																	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. 
															
													
									
	
		
	
																	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. 
																	Two very old three way switches. 
																	Your lighting circuit must. 
																	For simplicity the earth wire is not shown in the above diagram. 
															
													
									
	
		
	
																	3 way switch schematic wiring diagram. 
																	The screw terminals were on the front of switches many many years ago. 
																	The source is at sw1 and 2 wire cable runs from there to the fixtures. 
																	A two way switch uk schematic diagram of old wire colours. 
															
													
									
	
		
	
																	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. 
																	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. 
																	Notice the black wire is the only wire that we are controlling through the 2 way switch. 
																	Schematic diagram of new wire colours. 
															
													
									
	
		
	
																	This was unsafe having live electrical terminals so close to a metal wall plate. 
																	The switch wiring is all the same but the switch wire cable c leads up to a different set up. 
																	3 way light switching new cable colours 3 way light switch old cable colours 3 way light switch using a two wire control. 
																	Multiple light wiring diagram. 
															
													
									
	
		
	
																	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. 
																	Two very old three way switches are depicted in the photo above. 
																	A 2 way switch wiring diagram with power feed from the switch light. 
																	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. 
																	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.