How to Control One Light Bulb From Two Different Locations?

Electrical Technology

2-Way & 3-Way Switching Connections – Electrical Wiring Diagrams

What is Two Way & Three-Way Switching Circuits?

Two-way switching or (three-way circuits in the US) connection is used to control electrical appliances and equipment like fan, lighting points etc. from different places using 2-way & 3-way switches. The most common use of 2-way switching connection is staircase wiring where a light point can be controlled from two, three or even many locations. No matter what is the position of flowing electric current in the two way switch (ON or OFF), the connected appliance like bulb can be switched ON / OFF by pressing the button.

Two Way or Three Way Switch?

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 applications.

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Construction & Working of a 2-Way & 3-Way Switch

In North America, the 2-Way switch is also known as Single Pole Single Through (SPST) while 3-Way switch is known as Single Pole, Double Throw. The basic construction and working principle of 2-way switch is illustrated in (fig 1) below.

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For this kind of wiring installation, you will have the following requirements.

1 No of 4-Way Switch (Intermediate as 3-Way in IEC)
2 Nos of 3-Way Switches (Two-Way Switches in the NEC)
1 No of Light Bulb
Wires and cables as needed.

How to Wire a 2-Way Switch (3-Way – US)?

Below is a given schematic wiring diagram that shows how to wire a 2-way (or Three-Way – US) switch and control a light bulb from two different places.

Note:

The same purpose can be achieved by using the following two way switching connection in fig 3 as well.
Connect the Earth Wire to the connected electrical appliance as well as switches (always on Hot (Line or Phase) as per electrical regulation in your area.

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How to Control Light from Two Places?

The following two way switching connection can be used for the same purpose as mention above in fig 1 i.e. to control a light point from two different places by using 2-way switches

The following wiring shows to control a light bulb from two different locations using SPDT switches (also know as 3-Way switch in NEC and 2-Way switch in IEC.)

NEC wiring Diagram

IEC wiring Diagram

Additionally, you may use two 3-way combo devices (3-Way switch & outlet) to control a light bulb from two places (NEC – US) as follows where (both outlets always on.)

Moreover, you may use combination of Double three-way switches to control a single or two light bulbs from two locations as shown in the following diagram:

Two Way Switching to Control Light from Two Places in Staircase

As we discussed above, that the most common use of 2-way switches is to control a light point from different places like upper and downstairs i.e. lower entering door and upper door. This circuit is shown below:

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