A Guide to Microswitches

Reviewed by Stephen Bettles (Technical Support Engineer, January 2025)

 Microswitches are all around us in daily life. They are used in air conditioning units, washing machines, consumer devices such as refrigerators and microwave ovens, and lift buttons and door locks. These versatile switches are also used in robotics to control motion.

This guide looks at what microswitches are, how they work, microswitches types, and some of the typical applications of microswitches.

What is a microswitch? Microswitches are small, sensitive switches designed to operate over a long period of time (for tens of millions of cycles in some heavy-duty cases). They are quick to operate and very reliable. Microswitches typically make a distinctive ‘click’ when pressed, providing feedback to the device user, and don’t require much force to trigger.

Microswitches are electromechanical devices. The simplest type of microswitch toggles between ‘on’ and ‘off’ positions by moving a spring-loaded lever. When force is applied, the lever moves from the centre of the switch to either the on or off position. The first microswitches were developed in the US in the 1930s.

You may be asking, ‘What does a microswitch do?’ Simply put, a microswitch completes or breaks the flow of current in a circuit. Microswitches are often used as on/off switches for this reason.

So, how does a microswitch work? A microswitch usually features an actuator, a set of electrical contacts, and a spring-loaded lever. When the actuator is pressed or comes into contact with force, the lever moves, opening or closing the electrical contacts to make or break the flow of electricity.

Microswitches typically have three pins: normally closed (NC), normally open (NO), and common (C). In the normal condition, the actuator is not pressed. When the actuator is pressed, the NO pin connects to the common pin. 

Engineers choosing microswitches must consider a number of factors. They include:

• Whether the circuit is AC or DC and the level of voltage and current. A microswitch that is overloaded may fail. Since reduced energy consumption is desirable in electronics design, it may be necessary to specify a microswitch that works with low levels of current.
• The longevity of the microswitch. Some microswitches are designed to last for many cycles before they will fail. Durability can be achieved by using certain materials in the microswitch design such as fibreglass, rubber, nitrile, steel, or zinc.
• Microswitch dimensions. Microswitches are available in various shapes and sizes including miniature and sub-miniature designs. Size has an impact on how much current the microswitch can deal with, with large current applications needing a bigger microswitch.
• The operating environment. Technicians working with microswitches also need to specify a switch with the environment it works in in mind. For example, if the operating environment is humid, corrosive, or involves water exposure, specific designs are available.

You may be wondering how to test a microswitch. Safety is the number one priority. Before you test, ensure you are wearing the correct PPE such as eyewear and gloves, have insulated tools to hand, and have turned the power off. Use a voltage tester to confirm there is no voltage: Don’t presume the circuit is dead until you have verified it with a voltage tester.

One of the best ways of testing a newly wired switch is using a multimeter in continuity test mode. Before you test the microswitch, you can check that this mode is working by touching the multimeter probes, which should produce a beep. This indicates a complete circuit.

The next step is to disconnect the switch to isolate it, to ensure your test is accurate. Finally, connect the multimeter probes to the appropriate terminals (normally the common and NO). If the switch is on and functioning correctly, the multimeter should emit a beep when the actuator is pressed.  

If the switch isn’t working, the microswitch position or microswitch wiring may need to be changed. Don’t forget that your microswitch wiring diagram should feature the correct microswitch symbol.

Various types of microswitches and detector switches are used in a wide range of applications.

Microswitches are used in industry to control electrical components, sensors, lights, and alarms. They are used in fire alarms and emergency stop systems, to lock and unlock doors, and in heating, ventilation, and air conditioning applications. CCTV cameras also rely on microswitches to move. In robotics, microswitches help create robot motion, while in the automotive industry, microswitches are used to enable the transmission to engage the right gear, when brake pedals are depressed, and in car door-locking systems. In the home, microswitches are used on the control panel of microwave ovens, to turn washing machines on and off, and to detect the opening and closing of doors.

What is the use of a microswitch? It might be quicker to ask where microswitches aren’t used!

Need switches? RS carries a range of push button switches and components.