Safety Sensors on a Driveway Gate

The photo eye does one job: it interrupts a circuit when something breaks the beam, and the operator stops or reverses. The record kept at austin driveway gates the derek bordeaux group shows most nuisance stops on a driveway gate in Austin, TX trace back to where that eye was mounted, not to the eye itself. A safety sensor that cries wolf gets bypassed, and a bypassed sensor protects nobody.

Photo eyes: height, aim and sun

A pair of photo eyes mounts across the opening, usually a hand's width above the ground and again higher on the post. The sender and receiver must face each other squarely. West sun in the late afternoon, common on lots above Lady Bird Lake and in Tarrytown, can wash out a receiver that looks into it, so the crew flips the sides or adds a shield.

Edge sensors on the moving leaf

A safety edge is a strip on the leading edge of a swing gate or the end of a slide gate. It senses contact and stops the motion. On a swing gate the edge sits on the latch side. On a cantilever gate or track slide it sits on the leading end and on any gap near the fence where a hand or paw could be caught. Steel and aluminum frames both take them, and the wire runs inside the tubing back to the control board.

Loop detectors in the driveway

A loop detector is a coil of wire saw-cut into the pavement. It senses a vehicle sitting in the path and holds the gate open until the car clears. Roots, shifting clay and a slope that sheds water into the slot can crack the sealant and break the wire, so crews seal the cut well and avoid placing a loop where the pavement already cracks. The Barton Springs area and the creek lots near Zilker Park have ground that moves enough to test this.

False stops from dust, sprinklers and spiders

Dust builds up on the lens and cuts the signal slowly, over weeks. A sprinkler head that sprays across the beam triggers a stop every morning at the same time. Spiders like the warm housing and build a web across the lens, which breaks the beam without any car in sight. A wipe with a damp cloth, a re-aimed sprinkler and a small cover usually end the problem.

Testing the system

A crew tests every sensor by hand on the day of installation and again when the gate is handed over. Place an object in the path and the gate must stop or reverse. Do this at each sensor, with the keypad and remote both used to start the cycle. A sensor that fails the test gets fixed before the crew leaves the driveway.