The safety devices on a gate are what stop it hurting someone. Every gate needs the right combination for its size, its surroundings and who uses it – that's worked out when it's installed. Here's what each one does.
Photocells
Two small units facing each other – one sends an invisible infrared beam, the other receives it. If the beam is broken while the gate is closing, the gate stops and reverses.
- Where: usually across the opening on the outside, and often on the inside too.
- Good at: detecting cars and people walking through.
- Limits: the beam is a single line, so it can miss something lower or higher – a small child, a dog or a bike lying down. That's why photocells alone are often not enough.
Safety edges
Rubber strips fitted to the closing edge of the gate, or to posts and walls where trapping can happen. If the edge is pressed, the gate stops and reverses. They can be wired or wireless.
- Where: closing edges, hinge sides, and places where a gate passes close to a wall or post.
- Good at: protecting against crushing and trapping points the photocells can't cover.
Other sensors
- Radar or active infrared sensors detect people or objects in a zone, rather than a single line. Useful on busy or commercial gates.
- Vehicle loops – a wire in the driveway that senses a car, so the gate won't close on it.
Force limitation
Modern control boards sense if the motor meets more resistance than normal and reverse the gate. Combined with the safety devices, this keeps the closing forces within the limits in BS EN 12453 – which is checked with a force tester. See force testing.
Warning lights
A flashing lamp that warns people the gate is about to move, and while it's moving.
Guarding
Sometimes the best fix is physical – mesh on the gate where it passes a post, or covers over rollers and gears, so fingers can't get in.
Which does your gate need?
It depends on the gate, the site and who uses it. A quiet domestic swing gate might need photocells on both sides and safety edges at the trapping points. A busy commercial sliding gate will need more. I work this out for every gate I install or convert.
Problems with your sensors?
See diagnosing issues with electric gate sensors, or call, text or WhatsApp Adrian on 07855 781433.
Questions people ask me
Are photocells enough on their own?
Often not. They miss things outside the beam, so safety edges or other devices are usually needed too.
Can safety devices be added to an old gate?
Yes, in most cases. See upgrading an old gate system.
How often should safety devices be checked?
Test the photocells monthly yourself, and have everything checked at an annual service.