2 Position Switch Wiring Diagram

How to Control One Lamp from Two Different Places using 2-Way Light Switches ( Staircase Wiring Diagram ) ?

Two Way Switch or Three Way Switch: "Three-way" is the North American (USA) term for this type of switch used in the following tutorial. Most English-speaking countries (UK/EU) call them "two-way". The term for the pair of wires connecting the two switches also varies: "strappers" to the British and "travelers" to the US.

Please don't kill me to mention it 2-Way switch instead of 3-Way switch as whatever we have used is the same thing for specific purpose.

In today basic electrical wiring installation tutorial, we will discuss step by step method of staircase wiring installation by using 2-way switches (SPDT = Single Pole Double Through Switch). Also, the same wiring circuit diagram can be used for 2-way lighting or controlling electrical appliances from two different places by using two-way switches. The main purpose of two way switching circuit is that the appliances can be ON / OFF independently from any switch, no matter whatever is the current position of the switch.

Staircase Wiring Circuit Diagram Connection

Below is old-school staircase wiring circuit diagram. Here we can control a bulb from two different places by using two 2-way switches.

Staircase wiring circuit diagram - How to control a lamp from two different places by two 2-way switches?

Working & Operation of Staircase Wiring – 2-Way Light Switching

Consider the above 2-way switch wiring diagram which has been used to control a bulb in staircase. The schematic shows that circuit is completed and bulb is ON. Suppose you want to OFF the bulb from the upper switch at top of stair ( (upper portion of staircase) ) simply Switch OFF the switch then circuit will break and the bulb will be OFF. To switch ON the bulb again, just switch ON the same switch at upper portion of staircase. In other words you can OFF and ON bulb from upper switch at the top of stair. Obviously; you can perform the same operation from the bottom switches installed in staircase.

Now, let's see how we can do that from the other switch installed at the bottom of stair. Staircase wiring diagram - How to control a lamp from two different places by two 2 way switches

For this purpose, consider the figure given above. In this case, you can see that circuit is complete and bulb is ON. Suppose you want to OFF the bulb from the lower switch at bottom of stair. Simply OFF the switch, then again circuit will break and the bulb will be OFF. You can switch ON the bulb again to switch ON the same switch installed at the bottom or downstairs as shown in the fig.

To get the switching position in ON condition for light bulb, the above operation is same as the Exclusive-NOR (EX-NOR) logic gate truth table which is given below.

Switch ₁	Switch ₂	Lamp Position
0 = OFF	0 = OFF	1 = ON
0 = OFF	1 = ON	0 = OFF
1 = ON	0 = OFF	0 = OFF
1 = ON	1 = ON	1 = ON

Two Way Switching Control using Three Wires

It is the new 2-way switching connection method which can be used for staircase wiring as well as it is efficient as compared to the old-school method where 2 wires are used instead of three wires.

The current position of two way switching connection using three wires circuit is ON and the bulb is glowing. The circuit operation is same as mentioned in the above figures but the connection method is different as the first terminals of both switches are connected to the live (Phase) wire. The second terminals of both switches are connected to the bulb to provide live line supply while the Neutral is directly connected to the bulb as common wiring method.

This basic circuit is little confusing as by looking in it, it makes a short circuit (to the same wire which is not harm in this case) when both switches are ON or OFF which is making a loop to disconnect the live supply to the bulb, Hence, bulb will not glow in that case.

2 way light switching

To get the switching position in ON condition for light bulb, the above operation is same as the Exclusive-OR (EX-OR) logic gate truth table which is given below.

Switch ₁	Switch ₂	Lamp Position
0 = OFF	0 = OFF	0 = OFF
0 = OFF	1 = ON	1 = ON
1 = ON	0 = OFF	1 = ON
1 = ON	1 = ON	0 = OFF

Staircase Wiring using Intermediate Switch

This is not always the case, but in some cases like shared flats and long stairs, we may control the light point in staircase wiring from three different places by using two 2-way switches and an intermediate switch as shown in fig below.

Click image to enlarge

Staircase wiring connection using 2 two way switches and intermediate switch to control a light point from three different places.

2-Way Switching Applications and Uses

How to control a lamp from two different places by using two 2-way switches - staircase wiring diagram

The main purpose of two-way switching connection is to connect and control AC appliances and equipments from two separate locations.
It is mostly used in staircase wiring where a light bulb can be control (Switch ON / Switch OFF) from different places, no matter you are in the upper or lower portion of stair. Also, it does not depend on the switches position as well. You just have to press the switch button to OFF / ON to perform the switching operation.
It is also used in rooms having large area which has two entry and exit gates.
It is used to control any electrical (AC or DC) appliance or equipment like fan, light bulbs etc from two different places.

Julie Yougung