What is an Intermediate Switch & Its Working

A switch is an electromechanical device that operates manually. It includes one or more electrical contacts and these are allied to exterior circuits. Every electrical contact includes two states namely closed and open. Closed is nothing but contacts will touch to each other so that the flow of current will be there whereas open means two contacts will separate so there is no flow of current. A human-operated switch can be used to control the signal in a system. The best examples of switches are buttons on a computer keyboard, light switch, etc. Automatically operated switches are used for controlling the motions of machines. There are different kinds of switches like one way, two way, and intermediate. This article discusses an overview of an intermediate switch.

What is Normal Switch?

Definition: There are different types of commonly used and main switches are available such as normal switch otherwise an intermediate type. A normal type is also known as a one-way type (or) two-way type switch. These are used in normal lighting conditions.

One Way Switch

This type of switch is mainly used when you have only a single switch for a single light. The best example of this switch is a ceiling light in the bedroom. These switches are not expensive so used in simple circuits.

One Way Type
One Way Type

Two Way Switch

This kind of switch is used where there is a requirement of two switches to switch off a single light. For example in a hallway, one switch is used at the base of the stairs whereas another one is used at the top. The connection of this switch is shown below and it can be used as a one-way switch.

Two Way Type
Two Way Type

What is an Intermediate Switch?

This switch is very versatile and it is used where three switches are necessary to control a single light. It is expensive to compare with others. When you have three switches to control a light, then the center switch must be intermediate. An intermediate switch symbol is shown below.

Intermediate Switch
Intermediate Switch

This switch can also be used like a one way or two-way switch. A two-way switch can be used like one way or two-way switch, so these are frequently used in different applications. Actually, electrical retailers don’t vend one-way type switches due to the price difference.


Working Principle

Intermediate switch working principle is similar to a DPDT namely double pole double throw switch. This switch works by allowing three switches for controlling a single light. This switch is used in a multi-story building otherwise on a landing. Because the arrangement of switches can be done on top of stairs, the bottom of stairs, and the end of the landing. In that, an intermediate switch is used in the middle of the 2 two-way switches. By using these switches, controlling light can be done from 3 different places.

Intermediate Switch Wiring/Wiring Diagram

The intermediate switch includes four terminals where these terminals will change the flow of current from circuit to circuit. It also called three-way switches. The main function of this switch is to turn ON & turn OFF the electric supply in two ways. An intermediate switch connection and operation are shown below. It includes four contact pins namely A, B, C, and D.

Intermediate Switch Wiring
Intermediate Switch Wiring

Once the switch button is up, then the terminal contacts in the switch will attach terminal ‘A’ through terminal ‘C’. Similarly, terminal ‘B’ will connect through terminal ‘D’ as shown in the following figure. Alternatively, once the knob is downward then terminal ‘A’ can be connected to terminal ‘B” & terminal ‘C’ is connected to terminal ‘D’. So when the switch is upward, the vertical contacts like AC & BD are connected. Similarly, when the knob is downward, the horizontal contacts like AB & CD are connected.

How to Install Intermediate Switch?

The installation steps of this switch include the following.

  • This switch is used where the number of switches is necessary to control a light
  • It must be arranged among the first & last switches of the light circuit.
  • If we want to change an existing switch, then note down the position of the terminals as well as the position and connections of the cable.
  • These switches are applicable in one way or two-way switching.


The precautions while installing this switch include the following.

  • Before going to install this switch, we must consult a good electrician if we have any doubts.
  • Instructions must be read carefully
  • Always make sure that the supply is correctly isolated or not before doing the installation.
  • Take away the switch which is existing from the wall
  • Clean the dust in the wall box.
  • Always utilize the exact type of cable.
  • The layout of the terminal will change from one switch to another switch so check the position of the terminal connections cautiously.


The applications of an intermediate switch include the following.

  • These kinds of the switch are typically used in big rooms, halls and go down wherever numerous lamps are required to turn ON or OFF from various locations.
  • In addition, the lamp in a multistory building on the ground floor otherwise in car parking shadow can be controlled from any floor through an intermediate switch.
  • The light point can be controlled from three locations with the help of 2 two-way switches as well as an intermediate switch.
  • Wiring this switch in the middle of the staircase to turn ON/OFF a light from three different locations through 2 two way switches.
  • The lamp can be controlled from six locations with the help of 2 two-way switches & 4 intermediate switches. Also, various electrical appliances such as machines, alarms, fans, can also be controlled from different locations.

Thus, this is all about an overview of an intermediate switch, working, design, how to install, precautions, and it’s applications. This can be used as a 1-way otherwise 2-way switch but it is very costly because of being an extra complex circuit. These are used only when three otherwise more switches are used in the circuit. Here is a question for you, how to wire an intermediate switch as a two way?