Electrical DesignElectrical WiringHow ToLighting

How to Control One Lamp From Three Different Places?

3-Way & 4-Way Switching Connections – Electrical Wiring Diagrams

What is 2-Way & 3-Way Switching Circuits?

Three-way switching or (Four-way circuits in the US) connection is used to control electrical appliances and equipment like fan, lighting points etc. from more than two places. The most common applications of this configuration is staircase wiring, hallway & corridor wiring, hostel wiring, hospital wiring, tunnel wiring, godown wiring etc. where a light bulb is controlled from two, three or even more places for ON and OFF operations.

Two Way or Three Way Switch?

Three Way Switch or Four Way Switch: “4-way” is the North American (USA) term used for crossover switch. While mentioning the same thing, most English-speaking countries (UK/EU) call them “3-way” or intermediate switch. The term for the pair of wires connecting the two switches also varies: “strappers” to the British and “travelers” to the US.

Please ignore if we mention it 3-Way or 4-Way switch as they are interchange words representing the same thing.

Related Wiring Diagrams:

Construction & Working of a 3-Way & 4-Way Switch

The 3-Way switch is also known as Single Pole Double Through (SPDT). The basic construction and working principle of 3-way switch is illustrated in (fig 1) below.


Intermediate Switch or Crossover Switch - 4-Way Switch

Related Posts:

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 Control One Lamp From Three Places?

In fig 4, the wiring diagram shows how to control a light point from three different places by using two 2-way switches and an intermediate switch.


Fig 5 shows the same connection to control a light point from three places by using different symbols.

How to Control a light point from three different places by using two 2 way switches and intermediate switch

Related Posts:

Three Way Switching to Control Light from Three Places in Staircase

The following wiring diagram shows how to control a light bulb from three different places using two 2-way (or 3-way) switches and an intermediate switch or 4-way switch.

Staircase wiring connection using 2 two way switches and intermediate switch
Staircase wiring connection using 2 two way switches and intermediate switch

The following wiring diagram shows how to control a light bulb from three locations according to NEC and IEC.

Click image to enlarge

How to Wire 4-Way Switch & Intermediate Switch as 3-Way - IEC & NEC

Related Posts:

Applications of 2-Way & Three Way Switching

  • It is used to control electrical equipment and appliances from two different locations
  • It is also used in staircase wiring connections where a light point can be controlled from two or more different places.
  • It is used in large area premises, rooms, halls having two or more entry and exit points.
  • The main purpose of 2-way & 3-way switching is to control an electrical appliance, device or equipment, especially light points from two places.

Related Electrical Wiring Installations tutorials:

Electrical Technology

All about Electrical and Electronic Engineering & Technology. Join us on WhatsApp at Electrical Technology Official Channel, to receive the latest content, articles, and updates. You can also like and follow our social media networks below, or subscribe with your email to receive premium engineering articles in your mailbox.


      1. Not possible to get definitive results with a multimeter.
        Gate to source and gate to drain should read open circuit either polarity. That indicates either a good MOSFET, or one that is dead with the gate blown open. The only informative reading is when you see some resistance. Then you have a bad MOSFET, but you can’t make those readings with the device in circuit – or you likely will just be getting a reading from some other circuit elements.
        Drain to source will read open for an enhancement mode MOSFET but some value of resistance depending on the construction of the device for a depletion mode MOSFET.
        Some MOSFETS have an internal diode structure from drain to source so your reading will be polarity dependent.
        Unless you know what kind of MOSFET you have, multimeter testing is pretty pointless.

Leave a Reply

Your email address will not be published. Required fields are marked *

Back to top button