Off course cable sizes and protective device requirements can vary from job to job. The switch wiring.

2 Way Lighting
Two way switch wiring twin and earth. Forguive me if ive misread the posts but you can use the conduit method of 2 way switching. If you are doing a new install or replacing a two way switch system go for the three wire control method. The cable coming from the first light switch is connected as follows fig 5. The good thing about twin and earth cables is that the live and return are always in close proximity in the same cable so there is a cancelling effect. Intemediates can be inserted anywhere in the strappers. Also how to wire two way and two way and intermediate switching.
If you are using a plastic switch the earth wires will need to be connected to the terminal in the terminal box as shown above because there are no earth terminals on plastic switches. The second two way light switch is a bit easier to wire up. Any current carrying conductor emits an electromagnetic field. First of all we need to go over a little terminology so you know exactly what is being discussed. Where 0 represents the off condition and 1 represents the on condition. If you are doing a new install or replacing a two way switch system go for the three wire control.
The good thing about twin and earth cables is that the live and return are always in close proximity in the same cable so there is a cancelling effect. This cable is usually protected by a 6a mcb. This method can be dangerous if the neutral from the ceiling rose is connected to an alternate junction box on a different circuit. Two way light switch using 2 core cable. Now consider fig 2 again the live feed leaves the consumer unit fuse board and. Two way switch can be operated from any of the switch independently means whatever be the position of other switchonoff you can control the light with other switch.
Wiring a 2 way switch is about as simple as it gets when it comes to basic house wiring. Then at the other your common is the switched live. This is the new method to make a 2 way switching connection as it is slightly different from the two wire control method. The 3 coreearth cable differs from the twinearth on having an additional core which can prove very helpful when wiring two way or 3 way lighting circuits. Ill post a pic up if i can find one. Go to my switch terminology page where i discuss the terms used for the different types of home electrical switches.
This method is commonly used now days as it is efficient than the two wire control system. Video explains the connection required within switches. There are different ways to connect up two way lighting circuits one way is to use a twin earth cable between the two light switches. How to connect 2 way switch wiring using three wire control. It invloves taking a common from the loop terminal in a fitting. The circuit is wired in twin and cpc cables twin and earth cable and 3.
The twin and earth is your strappers. The red wire.