FAQs about E-Stops
General Information
What is an Emergency Stop (E-Stop) switch?
An Emergency Stop (E-Stop) switch is a safety device used to immediately halt machinery or equipment in emergency situations. It is designed to prevent injury to operators, damage to equipment, or other hazardous outcomes by cutting power or stopping motion when activated.
How does an E-Stop switch work?
When the E-Stop button is pressed, it activates a mechanism that interrupts the power supply or stops the motion of the machinery. The switch typically remains in the activated (latched) position until manually reset, ensuring the equipment cannot restart unintentionally.
What is the difference between a standard stop button and an E-Stop switch?
- Standard Stop Button: Used for normal stopping of equipment and may not have a latching mechanism.
- E-Stop Switch: Designed for emergency situations, featuring a latching mechanism to ensure the equipment remains stopped until manually reset. It is also required to meet specific safety standards.
General information
▶ What is an Emergency Stop (E-Stop) switch?
An Emergency Stop (E-Stop) switch is a safety device used to immediately halt machinery or equipment in emergency situations. It is designed to prevent injury to operators, damage to equipment, or other hazardous outcomes by cutting power or stopping motion when activated.
▶ How does an E-Stop switch work?
When the E-Stop button is pressed, it activates a mechanism that interrupts the power supply or stops the motion of the machinery. The switch typically remains in the activated (latched) position until manually reset, ensuring the equipment cannot restart unintentionally.
▶ What is the difference between a standard stop button and an E-Stop switch?
- Standard Stop Button: Used for normal stopping of equipment and may not have a latching mechanism.
- E-Stop Switch: Designed for emergency situations, featuring a latching mechanism to ensure the equipment remains stopped until manually reset. It is also required to meet specific safety standards.
Compliance & standards
What standards apply to E-Stop switches?
E-Stop switches must comply with international safety standards, including:
- IEC 60947-5-5: Specifies requirements for emergency stop devices with mechanical latching.
- ISO 13850: Defines the principles for designing emergency stop functions in machinery.
Are E-Stop switches required by law?
In many industries, E-Stop switches are mandated by safety regulations and standards to protect workers and equipment. Compliance with standards such as ISO 13850 and IEC 60947-5-5 is often legally required.
What is the required color of an E-Stop?
The background around the E-stop should be yellow to ensure high visibility and contrast.
Functionality and features
What is safe break action in E-Stop switches?
Safe Break Action ensures that the contacts inside the E-Stop switch physically separate (open) even if they are welded or stuck. This guarantees the emergency stop function will always work, enhancing safety and reliability.
What are push-in terminals, and why are they beneficial?
Push-in terminals allow for tool-free, quick, and secure wire connections. Benefits include:
- Faster installation and maintenance.
- Reduced risk of loose connections.
- Vibration resistance for reliable operation in harsh environments.
What is the difference between NC and NO contacts in E-Stop switches?
- NC (Normally Closed) Contacts: The circuit is closed in the default state and opens when the E-Stop is activated. This is the standard configuration for safety circuits.
- NO (Normally Open) Contacts: The circuit is open in the default state and closes when the E-Stop is activated. This is less common in safety applications and is usually used as a monitoring contact.
What are the different types of E-Stop release mechanisms?
E-Stop switches use different release mechanisms to reset after activation, depending on safety needs and application requirements:
- Twist-to-Release – Requires twisting (usually clockwise) to reset, preventing accidental reactivation.
- Pull-to-Release – The button must be pulled outward to reset, offering a simple and intuitive operation.
- Key-Release – Requires a key to unlock and reset, adding security but limiting accessibility in emergencies.
- Single-Unit E-Stops – Combines pull-to-release or twist-to-release in a compact design, ensuring reliability and compliance with safety standards.
Each mechanism is designed to balance safety, usability, and security for different industrial applications
Installation & maintenance
How often should E-Stop switches be tested?
E-Stop switches should be tested regularly, as part of routine safety checks, to ensure they function correctly. The frequency depends on the application and usage but should align with manufacturers recommendations and safety regulations.
Can E-Stop switches be reset automatically?
No, E-Stop switches are designed to remain in the activated position until manually reset. This prevents accidental or unauthorized restarting of machinery, ensuring safety.
What is the recommended mounting height of an E-Stop?
The E-stop should be mounted at a height that is easily accessible to operators, typically between 0.9 meters (900 mm) to 1.2 meters (1200 mm) from the floor.
This range ensures that the E-stop can be quickly reached by most operators, whether standing or seated.
Application & usage
Can E-Stop switches be used in harsh environments?
Yes, many E-Stop switches are designed with robust housings and high ingress protection (IP) ratings (e.g., IP65 or higher) to withstand harsh conditions such as dust, moisture, and vibration.
Can E-Stop switches be used in robotics?
Yes, E-Stop switches are critical in robotics and automation systems to ensure safe operation. They are often integrated into control panels or placed at strategic locations for quick access.
How do I choose the right E-Stop switch for my application?
Consider these key factors:
- Compliance – Ensure it meets IEC 60947-5-5, ISO 13850, or UL 60947-5-5 for safety compliance.
- Release mechanism – Choose twist-to-release, pull-to-release, or key-release based on security needs.
- Environmental protection – Select an appropriate IP rating (IP65, IP67) for dust, moisture, or vibration resistance.
- Electrical & mechanical ratings – Verify voltage, current capacity, and durability for high-use applications.
- Contact configuration – Use NC contacts for safety circuits, with dual-channel options for redundancy.
- Additional features – Consider illumination for visibility, shock resistance, and required certifications (CE, UL, CSA) for regulatory compliance.
Choosing the right E-Stop ensures reliable emergency shutdowns and workplace safety.
