What must the safety edge on a powered commercial door actually do?
Stop the door when it meets something, obviously. But the standard behind that word is specific: only a monitored device counts as entrapment protection, it should be tested monthly, and a door whose close button suddenly needs holding down is telling you the device has dropped out. Here is what a facility manager should actually know about the rubber strip on the bottom bar.
A door closing without working entrapment protection is a liability with a motor on it. We test, repair and replace safety edges and photo eyes on commercial doors across the corridor.
Call (905) 536-5369What does an edge sensor actually do?
It detects an obstruction and signals the operator; the operator decides what to do with the signal, typically stop or stop-and-reverse. That distinction matters: the strip on the bottom bar does not control the door, it informs the motor, which is why the edge and the operator have to be evaluated together rather than bought separately off two shelves.
Source: DASMA Technical Data Sheet #368, Edge Sensors (PDF), Introduction. Checked 7 September 2026.Monitored or non-monitored: why is that the whole question?
ANSI/CAN/UL 325, the safety standard commercial door operators are built to, splits edge devices in two, and the split is what your liability position rests on:
- A monitored system is one the operator itself checks: it detects a short, an open circuit, a cut wire, a lost wireless signal. If the device drops out, the operator refuses to close normally. DASMA’s guidance is to check and test the device monthly. Only monitored systems may be used as entrapment protection.
- A non-monitored system is not checked by the operator. A cut wire simply means no signal, and nothing notices. These are legitimate for property protection, stopping a door from hitting a trailer, but DASMA states plainly that non-monitored systems may not be used as entrapment protection.
The practical question for every powered door on your site is one sentence: is the device on this door monitored, and when was it last tested? If nobody can answer it, that is the inspection.
Source: DASMA TDS #368 (PDF), Principles. Checked 7 September 2026.Why does the close button suddenly need holding down?
Because that is the designed behaviour, not a fault in the button. Under UL 325, when a powered door has no properly functioning sensing edge, photo eyes or other sensing device, the operator must be wired so the close button requires constant pressure all the way down. A door that used to close from a tap and now needs the button held has lost its entrapment protection and is telling you so. Treat it as a service call, not a workaround to train the staff on.
Source: DASMA Technical Data Sheet #269, Rolling Door Performance Evaluation by a Facility Manager or a Building Superintendent (PDF), Electric Operation. Checked 7 September 2026.What types of edge are on these doors?
Five families, and it is worth knowing which one you own, because they fail differently:
- Pneumatic: a hollow rubber profile; compression works a pressure switch. A puncture, a cut tube or a lost end plug can silently take it out, and the edge should not sit compressed when the door is closed.
- Electric: two conductive strips separated by a gap; compression closes the circuit. Wired configurations exist in both monitored and non-monitored forms.
- Optical: a light beam inside the astragal; compression breaks the beam. Can self-monitor for faults.
- Capacitance: a non-contact field that senses conductive objects, people and metal, before contact. Worth knowing its limit: it does not detect wood, paper or plastic.
- Light-beam edge: a non-contact transmitter and receiver travelling with the door.
Connections matter as much as the edge: hard-wired coil cords, inductive transmission along the lifting cable, or wireless pairs, and the wireless kind has batteries, which makes it a maintenance item with a calendar.
Source: DASMA TDS #368 (PDF), Types of Edges and Means of Connections. Checked 7 September 2026.How do you test it without guessing?
Per the manufacturer’s written instructions, and at both ends. DASMA’s building-staff guidance is explicit about testing the sensing edge at each end of its length, because a partial failure can leave one end live and the other end dead. Check the visible wiring between the edge and the operator for damage while you are there, and put what you found in the door’s log. On our maintenance program the edge and photo-eye test is a line item on every visit, which is the difference between believing the door is protected and being able to show it.
Sources: DASMA Technical Data Sheet #270, Recommended Rolling Door Maintenance Practices for Building Maintenance Supervisors (PDF), Door Operation item 7; DASMA TDS #368 (PDF), Important Safety Information. Checked 7 September 2026.