Sensing Edge

A sensing edge is a contact-based safety device mounted across the full width of the bottom bar of a commercial overhead or rolling door. Inside the rubber or neoprene tube is either a pneumatic tube that generates an air-pressure signal when compressed or an electrical contact that closes a circuit when the tube is squeezed. Either way, any contact with sufficient force triggers the door operator to stop and reverse.

Sensing edges are the primary entrapment protection device for large commercial doors where photo-eye sensors alone are insufficient. A photo-eye beam is mounted at a fixed height and may not detect a person who is prone or crouching below the beam, or a low-profile vehicle obstacle. The sensing edge contacts the obstruction directly at the door's bottom edge, providing a last-resort detection point regardless of the obstruction's height or position.

Commercial doors over a certain size and weight are required by UL 325 to incorporate a sensing edge in addition to other entrapment protection devices. The specific requirements depend on the door type, size, and application, and are detailed in the applicable ANSI and UL standards.

Sensing edges require periodic inspection. The rubber tube can harden or crack with age and may no longer compress enough to trigger the sensor reliably. The electrical or pneumatic connection at the end of the tube is a common failure point, especially on doors that see heavy traffic. Annual testing—pressing the sensing edge manually while the door is closing—confirms the reversal function is working correctly.