Emergency Stop Buttons Selection Guide
Emergency stop buttons come in twist-release, pull-release, key-release, illuminated and enclosed types; choose by release method and mounting location.
This guide explains what to check when selecting products in the Emergency Stop Buttons category.
Emergency stop button types
Models are divided by how the latching head is reset and where the button is mounted.
- Twist-release: The lock is released when the head is turned in the direction of the arrow. In Schneider Electric product names it appears as "released by turning", and in ABB product data as "turn-release".
- Pull-release: The head is reset by pulling it back. The EMAS CP series has pull-release and windowed pull-release types.
- Key-release: The lock is opened only with a key; chosen where the authority to reset should remain with specific people.
- Illuminated: Depending on the connection, the lamp shows the state of the button; on lines where many buttons are connected to the same circuit, it makes it easier to find the button that was pressed. In Isıso and Schneider Electric product names, the lamp voltage is given as 24 V AC/DC or 220 V AC.
- Enclosed and surface-mounted: The button comes with its own enclosure and is mounted at points away from the panel. The Schneider Electric XALK, ABB CEPY1 and Gwest enclosed models and ABB's surface-mounted Smile and EStrong families are in this group; for the Smile models, M12 connector and cable connection options are stated in the product data.
What to look at when choosing an emergency stop button
- Mounting hole and head diameter. The two dimensions are separate things: in EMAS product names, 22 mm is the panel hole, and 30, 40 or 60 mm is the diameter of the mushroom head. In Isıso product data the diameter is also written as 22 mm; the EMAS D series is named as 16 mm.
- Reset method. The choice between twist-release, pull-release and key-release types is made according to who will reset the button and under what conditions.
- Contact count. In a single-channel stop circuit one NC contact is used; a button to be connected to the two-channel input of a safety relay needs two separate NC contacts. The ABB product data includes models with 2 NC contacts, and on the EMAS and Schneider Electric side there are 1NC and 1NO + 1NC models. The machine's risk assessment determines the number of channels; the related devices are in the safety relays category.
- Protection rating. EMAS product names include IP50 and IP65, and ABB product data includes IP65 together with IP66, IP67 and IP69K. According to IEC 60529, IP50 means protected against dust but not against water, and IP65 means dust-tight and protected against water jets.
- Locking. In the product data of some models, the movement or button model is written as "spring-return". Confirm from the manufacturer's data that a button to be used as an emergency stop latches in the pressed position.
Color, locking and resetting
The common color scheme on emergency stop devices is a red head on a yellow background; this scheme is described in EN ISO 13850. For the enclosed models in the category, the enclosure color is stated as yellow-black or yellow-gray.
After the button is pressed it must stay latched, and releasing the lock must not restart the machine by itself; restarting is done with a separate command. This behavior depends on the design of the control circuit together with the button and is set up according to the project and manufacturer data.
Emergency stop is regarded as a measure that complements the main protective measures in machine safety. For ordinary start and stop commands, mushroom head push buttons and spring-return push buttons are used.
Brands in this category
- Schneider Electric: Twist-release and key-release buttons with 40 mm heads, coded XB4 for metal and XB5 for plastic, illuminated XB5 models, XALK-coded enclosed emergency stops, ZB4- and ZB5-coded heads.
- EMAS: Twist-release, pull-release, key-release and labeled types in the B, CP, CM, KB, MB, H and D series. The CM series has a metal housing, the others plastic.
- ABB: Surface-mounted Smile and EStrong, panel-door-mounted INCA families, the CE4T button with a 22 mm hole, and CEPY1-coded enclosed models.
- Isıso: IA5-coded illuminated and non-illuminated buttons, ISM metal and ISP plastic series; product names state 1 NC contact.
- Gwest: Yellow-black enclosed emergency stop button with NC contacts.
Order notes
- The sales unit is the piece. Some Schneider Electric products are listed as parts: by product name, ZB4BS844 is an operating head and ZB6Y7330 is a legend. If you are looking for a complete button, look at the models whose product name states the contact arrangement (1NC, 1NO + 1NC).
- Additional contact blocks and button heads are in the push button and pilot light accessories and spare parts category; check compatibility against the button series.
- You can use the manufacturer code in the search; the code is recorded in the name for some products and in the stock code for others (for example XB5AS8445, CP200E, IA5-01ZS).
Comparison and selection table
| Selection Criterion | Twist-to-Release E-Stop | Pull-to-Release E-Stop | Key-Release / Enclosed E-Stop Station |
|---|---|---|---|
| Reset Mechanism | Rotate mushroom head in arrow direction | Pull mushroom head outward to unlatch | Turn mechanical key to release latch |
| Contact Block | 1 NC or 2 NC direct-opening (IEC 60947-5-5) | 1 NC / 2 NC + 1 NO status contact | 1 NC / 2 NC inside yellow IP65 enclosure |
| Mounting & Head | Ø22 mm cutout, Ø30/Ø40/Ø60 mm red head | Ø22 mm cutout, red mushroom actuator | Surface-mounted yellow/red safety station |
| Typical Application | Standard machine panels & control desks | Conveyors, presses, pendant stations | High-hazard lines requiring authorized reset |
Frequently asked questions
Why is an NC contact used in an emergency stop button?
An NC (normally closed) contact keeps the circuit closed while the button is not pressed and opens it when pressed. This way not only pressing the button but also a broken wire or a loose terminal block cuts the circuit, and the machine reacts in the direction of stopping. In a stop circuit built with an NO contact, the same fault goes unnoticed and the button does not work when pressed. For this reason the NO contact is used for status indication, not in the stop circuit.
Does the machine start by itself when the emergency stop button is reset?
It must not. When the emergency stop button is pressed it latches and stays in that position until it is reset by turning, pulling or with a key. Resetting the button only removes the stop command; a separate start command is needed for the machine to run again. This behavior is provided by the design of the control circuit together with the button; the circuit is set up according to the project and manufacturer data.
What does 40 mm mean on a 22 mm emergency stop button?
22 mm is the diameter of the panel hole the button is fitted into; 40 mm is the diameter of the mushroom head. In this category, models with 30, 40 and 60 mm heads are listed for the same hole diameter. As the head gets larger, it becomes easier to press the button with the palm and with a gloved hand, and the spacing to be left between adjacent buttons also increases. The two dimensions are stated separately in EMAS product names.
Should I choose an emergency stop button with a single NC contact or double NC contacts?
This depends on the number of channels in the machine's safety circuit. In a single-channel circuit one NC contact is used. For a button connected to the two-channel input of a safety relay, two independent NC contacts are needed; the relay compares the two channels and catches a contact or wire fault. The required construction is determined by the machine's risk assessment, and the button is selected accordingly.
Why is the yellow label under an emergency stop button used?
In the common scheme described in EN ISO 13850, there is a yellow background behind the red head. If the panel door or enclosure is not yellow, this background is provided by a yellow label fitted under the button. For models whose product name says labeled, check the shape of the label from the product image; for the text and symbols on the label, the machine's technical file is the basis.