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What Is a Key Switch?

Maggie Worth
Maggie Worth

A key switch is a mechanical switch that can only be activated using a key. Keys are generally assigned to users, allowing the restriction of access to the controls. The most commonly recognizable example of a key switch may be an automobile ignition. Such switches, however, are frequently used in manufacturing and industrial environments as well.

The principle behind an industrial key switch is virtually the same as the principle behind an automotive one. In order to turn a machine on or off, a key that fits the switch must be inserted and the switch turned. In a manufacturing environment, these switches frequently provide access to other actions as well, such as the ability to adjust settings and speeds.

One main purpose behind a key switch is to restrict access to the machine. Switches are often used in the cases of very expensive or potentially dangerous equipment. Machines critical to operations may also be turned on and off via a key switch.

A car's ignition switch and key.
A car's ignition switch and key.

Another primary benefit of key switches is that they are virtually impossible to engage accidentally. Unlike a flip switch or push switch that can be bumped, unintentionally turning a machine on or off, the operator of a key switch must actively insert the correct key and then turn the chamber. This makes such switches a natural choice for machines that take a long time to shut down or restart and for critical operations equipment, such as that controlling the air or power inside a plant.

Often, the keys that fit such switches are traditional metal keys with a series of notches carved into one or both edges. These notches engage with wards inside the switch, much like the wards of a lock. Only keys with the right pattern, or master keys made to work with a number of different switches, can be used to engage the switch.

Many modern key switches, however, now use electronic keys. These switches are significantly more expensive, but have the advantage of being able to assign a specific key to a specific individual. This allows a company to track who activated switches at a given time.

To add a second layer of security, a machine may be installed with a second distinct key switch. In these cases, the keys needed to activate each switch are different and are assigned to different individuals. Usually, each switch must be activated in sequence. In some cases, the switches must be activated simultaneously.

Discussion Comments


@miriam98 - I’m glad that worked out for you. What I wonder about is what a universal key switch looks like – or how it works.

I did something really dumb once, locking myself out of the house. I left the house through the garage and accidentally left the garage door opener inside, along with my house keys.

How it happened I don’t remember, but it did. I ended up calling one of those pick lock companies, and within twenty minutes a technician was out, picking the lock on my front door.

It was quite embarrassing to have to explain to him how I got locked out. I noticed he had a toolset, consisting of a master key and some other pins and stuff.

It didn’t take him but a few minutes and the lock was opened. Clearly this is a skill that would be potent in the hands of a criminal.


My car wouldn’t start one day. I tried everything. I thought it was the battery, the alternator, but these checked out okay.

I dreaded going to the mechanic because I thought that it was going to cost a lot of money and I couldn’t afford to spend a bunch on car repair, and I wasn’t that savvy myself.

It turned out to be something simple – the key switch on my car. Thank goodness. Automotive switches are fairly easy and inexpensive to replace.

I have no idea what caused it to go bad; maybe they just wear out over time. But it was an easy fix for the mechanic and I didn’t have to pay too much.

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    • A car's ignition switch and key.
      By: JackF
      A car's ignition switch and key.