Learning, Wiring,

How to Wire an Emergency Stop Button Diagram (Walkthrough and Steps)

As you know, safety is of utmost importance in any industrial or commercial setting, and that’s why emergency stop buttons are a crucial component of many machines and equipment. These little devices, also known as e-stops, allow workers to quickly and easily stop a machine in an emergency, preventing serious injury or damage to equipment.

Now, I know that wiring an emergency stop button may seem daunting, but trust me, it’s a pretty straightforward process that can be accomplished with some basic knowledge of electrical wiring. By the end of this article, you’ll clearly understand how to wire an emergency stop button properly. So, let’s get started!

Understanding the Emergency Stop Button Wiring Diagram

Before anything else, let’s look at the wiring diagram to understand how it works. 

The wiring diagram has five key components that you’ll need to wire together:

  • A Three-phase Contactor
  • Four Terminal Emergency Stop Switch
  • Start Push Button Switch
  • Stop Push Button Switch
  • A Buzzer

At the far upper left of the diagram, you’ll notice an arrow that says power supply. This is the main source of electricity for the entire circuit. These are usually present in households as a break circuit box or other similar electrical devices. Don’t worry too much about this; you can connect the emergency stop diagram to any new circuit in your home. 

The most important component here is the emergency stop switch.

Most models, if not all, are constructed with a four-terminal design of two NC and two NO terminals. NC, meaning “normally open,” is used to control the power supply, while NO, meaning “normally closed,” is used by the indication circuits (in this case, the buzzer). These terminals allow the emergency button to cut off the load circuit’s power and activate the buzzer. Normally, the emergency button and buzzer go hand-in-hand, but if you opt not to use the buzzer, you don’t need to connect anything to the NO terminal. 

The star of this diagram may be the emergency switch, but, in reality, most of the wiring is connected to the three-phase contactor. 

The contactor contains magnetic coils that control the power supply passing through it. An external start and stop push button switch are connected to the contactor. These switches connect and cut off the load passing through the contactor.

To turn off the power supply, you must manually locate these switches without the emergency stop button. Using an emergency stop button bypasses that need by automatically activating the stop push button switch and disconnecting the load from the main power supply. 

Don’t get overwhelmed by the wire connections and components present in the diagram. You can properly wire any emergency push buttons if you understand what each component does and which terminals should be connected. 

How to Wire an Emergency Stop Button

Step 1: Preparation

There’s nothing more annoying than going back and forth to the hardware store for supplies; you can avoid this by getting everything you’ll need for the wiring process. 

The main components you need are: 

  • The Emergency Switch
  • A Three-phase Contactor
  • The Manual Start and Stop Switches
  • Wires
  • A Buzzer (Optional)

You’ll also need basic tools like screwdrivers (Philips head and flat head), wire cutters, pliers, and a soldering iron. Heavy-duty tools like power drills and a heat gun are needed if you affix the emergency switch to the wall or want to wrap the wires in protective heat shrink tubing. Of course, those mentioned steps are entirely optional.

Turn off the circuit box or whatever power supply you connect to the emergency stop. Remember that we’re dealing with live electricity here, so ensure your safety by turning off the power supply before connecting any devices or wires. You can also add another layer of protection by wearing electrical safety gloves during the wiring process. 

Step 2: Stripping and Connecting the Wires

Many people are intimidated by the wiring process because there are just so many wires and terminals to connect. 

Thankfully, the terminals and wires included in the emergency buttons are labeled and come in specific colors.

Start by wiring the contactor with the power supply. Notice that colored wires are coming from both ends of the contactor; look for the end where the wires are labeled with L1, L2, and L3. Strip the end of those wires and match the wires with the terminal by checking the colors of the wires and terminal or the label indicated (a red L1 wire should be connected to a red L1 terminal, and so forth). Solder the wire to the terminal to establish a proper connection. The other side of the contactor is to be connected to the device you’re supplying the load to, so leave that alone for now.

wiring diagram for emergency stop switch

Next, connect the other components by following the wiring diagram above.

Suppose you get confused about which wire goes where. Remember that all terminals present in the components are labeled according to their use. NC terminals on the emergency switch should be connected to the NC terminal of the manual stop switch. In contrast, the NO terminals on the emergency switch are connected to the NO terminals of the manual start switch. In short, terminals with the same labeling should be connected. 

There’s no need to rush through the wiring process. Always refer to the diagram and check the labeling of the terminals before connecting any wires. 

Step 3: Finishing Up and Testing

We’re not exactly done with the wiring process yet.

There should be three unconnected wires (labeled T1, T2, and T3) on the other end of the three-phase contactor. Connect these wires to whatever load or device you’re supplying power to. Turn on the power supply once the connection is established. Next, test out the emergency push button. The power should be cut off immediately, and the buzzer, assuming it was added to the circuit, will activate if the wiring is done correctly. 

Video References

Jr Electric School

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Genesis Engineering


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About Sam Orlovsky

AvatarCertifications: B.E.E.
Education: University Of Denver - Electric Engineering
Lives In: Denver Colorado

Electrical engineering is my passion, and I’ve been in the industry for over 20 years. This gives me a unique ability to give you expert home improvement and DIY recommendations. I’m not only an electrician, but I also like machinery and anything to do with carpentry. One of my career paths started as a general handyman, so I also have a lot of experience with home improvement I love to share.

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