Emergency Stop Button Switch Wiring Diagram and Connection

Hey, in this article, we are going to see the wiring diagram of Emergency Stop Button switch and its connection procedure. The emergency stop button switch is also known as Emergency Power Off or EPO switch because it is mainly used to turn off the power of a machine or electrical system during an emergency. It is also known by different names such as Kill switch, Emergency Stop(E-Stop), Emergency Off(EMO), etc. It is basically a safety mechanism to shut down the electrical system or machinery immediately when the manual control fails. Emergency switches are used in industrial machinery, equipment, vehicles, cranes, heavy machinery, and many other places.

As the emergency is used in different places and different applications, so its placement and connection also be different according to different applications. So, in this article, we are going to learn the function and connection procedure with the help of a wiring diagram. It will clear your basic knowledge, so you can connect it anywhere easily.

Emergency Stop Button Switch Wiring Diagram

First of all, let's see the wiring diagram of the emergency switch.

Terminals and Contacts of an Emergency Switch

An emergency stop switch is basically an NC switch but some switches have NO terminals also. Generally, the two terminal switches have NC contact only, in the normal condition it keeps the contact closed and allows the current to flow through it but when we operate the switch, it disconnects its NC contact and stops the current flow through it. These types of switches are widely used. 

On the other hand, the four terminal emergency switches have both NC and NO contacts. NC contact is used for power control and the NO contact is used for the indication circuits. When we operate this switch it will shut down the power of the load circuit or machinery and activate the indication devices such as the buzzer, so people will be aware that the emergency switch is pressed for an emergency.

In the above diagram, we have shown a four-terminal EPO switch where both NC and NO terminals are available. If you do have not any indication device then you can keep empty the NO terminals.

Let's know about the above wiring diagram. Here, you can see a three-phase contactor is used that can be controlled by the start and stop push button switches. The start and stop push button switches are connected to the magnetic coil of the contactor. So when we press the start push button the contactor will activate and when we push the stop push button switch the contactor will deactivate. Basically, these switches are connected in series with the power source and contactor coil.

As we know that the NC terminal of the emergency switch is used for the power control, so it is also connected in series like the start and stop push buttons. So when operating this switch the contactor will disconnect from the power supply and the contactor will deactivate so the load will be disconnected from the main power supply.

Emergency Switch Connection Procedure

1. Use the NC terminal to connect with the electrical power system that is to be controlled.

2. Connect it in series with the power source and load or device that is to be turned off during an emergency.

3. Connect the indication devices with their NO terminals. Here also the series connection is required between the power supply and indication device.

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