So, immediately it should be noted that the switch( it can still be called that way) is not used alone, two products must be present for controlling a minimum. With regard to the connection of wires, the principle does not differ from the usual option of connecting the light switch - zero goes directly to the luminaire, the phase goes to break. The only difference is that in the circuit of connecting the single-key pass-through switch, not one phase( as in the classical version) but two is connected at the output. Output 2 contacts are connected to the next switch, which has one wire to connect to the chandelier.
A photo on which you can see the real picture of the switching of the cores to 2 lamps:
The output of the second switch has 2 contacts, In this example, two
lamps are used. In words, it is a little difficult to perceive the information, so we provide an electrical circuit for connecting a single-key pass button: 
As you can see, two single-key devices are connected with a three-core cable, which in turn must have a suitable core diameter. On how to choose the cross-section of the cable in terms of power, read the corresponding article!
A visual video example will show you the essence of the connection:
wiring instruction. I would also like to mention that a variant of the scheme in which there are 3 or even 4 single pass-through switches is not uncommon. In this case, you can turn on / off the light from 2, 3 and even 4 places, which is very convenient when you are in a long corridor. To make such a chain of control, you need to use another kind of product - cross, which are intermediate elements of the scheme.
With regard to the drawing you will be installing, it looks like this:
This option allows you to control the luminaire from three locations. In the event that you wish to switch off from four places, another cross switch is added to the circuit. 
That's all I wanted to tell you about the scheme for connecting pass-through single-key switches. As you can see, nothing is complicated, the main thing is to act carefully and observe the switching according to the color marking of the wires! Finally, we recommend that you pay due attention to the choice of the manufacturer of products. That such a lighting control system has served you for a long time, buy products from well-known manufacturers: ABB, Schneider( Schneider), Legrand( ladder).From inexpensive firms we can advise you Viko( вико), whose production has an optimum parity on cost and quality!
Also read:
- Wiring in the junction box
- Wiring diagram for the two-switch
- How to determine the cross-section of the wire and cable?
