The 2 way switch acts as 2 switches that can control a single appliance. This is a 2 switch for a single appliance. You might ask a question here why we want or need 2 switches for a single appliance while we have one.
The two-way switches are generally used for staircase case lightning and other lightning systems where we want to take control of appliances from two different locations. Suppose you are on the top of stairs and want to turn on the light above the stairs then using the 2 way switch you can turn on/off the same light with two different areas or locations. Here you can turn on the stairs light either from top of the stairs or from the bottom stairs using the two way switch. You can use the two way switch either on stairs, garage or in the garden where you can switch the garden light either while in the garden or when inside the hall or in home.
Fig 1: 2 Way switch connection
Wiring Of 2 Way Switch
As you can see in the pic below Common wiring that goes in the middle is the common pin of two switches and the Line L1 and L2 pin on both switches that carry the live current of the power source. When the first switch plunger moves down it makes the connection with line wire and then on the other side of the second switch is in up position making contact with bulb live wire and making a close circuit to light the bulb. Now suppose if we move the switch plunger to up then it discontinues the connection even if the first switch plunger in up position so the light connection is open and hence the light get turned off.
Now let us talk about the second situation if the plunger of the second switch moves upward then it connects the light bulb live wire and while the first switch plunger in down position in touch with live wire so the bulb can light up, If the second switch plunger get down then disconnects the connection with bulb live wire and hence cause the open circuit and hence the bulb light turns off so in this way the 2 way switch an be used to power the bulb on/off while both switch are located in entirely different locations.
Fig.2: Turning the light on using the first switch while the 2nd switch plunger in up mode Fig. 3: Switch off from first switch while 2nd switch plunger in off position Fig. 4: Turning the switch on/off from second switch while the first switch plunger is in down position.
Difference between 2 Way Switch And One-way Switch
The Two way switch costs more and the material and components and wiring required is more than one way switch. The Two way switch has the advantage in that you can control the appliance from two different locations. The two way switch uses 2 switches while one way switch uses 1 switch and simple wiring while the wiring of 2way switching is complex.
The main difference of a two way switch is unlike the one way switch it can mark as on or off while the 2 way switch depends on and off of switches that are present on other locations.
One way switch is used in a small area and room while two way switches are used in stairs, hall or in larger areas.