Safety Beam Sensors #2
Why I Recommend Two Beams for Swing Gates
Safety Beam Sensors #2 – Why I Recommend Two Beams for Swing Gates
Most swing gate installations are fitted with only one photoelectric safety beam, usually positioned near the closed gate position.
This setup provides protection when the gates are almost closed, but it does not protect the full travel path of the gates while they are opening or closing.
The Problem With a Single Beam
With only one beam installed near the closed position:
The entrance is protected only at the end of the closing cycle.
The main gate travel area remains unprotected.
A vehicle or pedestrian can be inside the gate opening area without being detected.
This becomes particularly important in real-world use, especially when:
A vehicle is exiting the property while the gates are closing.
A vehicle approaches from the street side while the gate is closing.
The gate is triggered remotely and the operator cannot see the full driveway.
In these situations, the system may continue closing even though something is already within the gate opening zone.
Gate Operation Hazard Zone
Between fully open and fully closed, there is a hazard zone where the gate is moving but no safety beam is active.
This means:
A vehicle can be in the driveway opening without breaking the beam.
The gate can still continue its closing cycle.
The obstruction may only be detected at the final closing position (or not at all, depending on geometry and timing).
This is the area shown as the “Gate Operation Hazard Zone” in the accompanying diagram.
Why a Second Beam Makes a Difference
Installing a second photoelectric safety beam near the fully open gate position provides protection at both ends of the gate travel:
Beam 1 protects the closed position.
Beam 2 protects the open position.
This setup significantly reduces the chance of the gate closing while a vehicle or pedestrian is moving through the opening.
In practice, it means:
The system detects movement in the driveway earlier.
The gate is prevented from closing when someone is entering or exiting.
There is protection at both critical points of the gate cycle.
Recommended Setup
For swing gates, I recommend:
One safety beam near the closed position
One safety beam near the fully open position
This provides a more complete level of protection across the entire gate operation area, not just at the end of the closing cycle.
Final Note
A single safety beam meets the minimum requirement in many installations, but it does not always provide full protection of the gate travel zone.
Where practical, installing two beams is a simple upgrade that significantly improves operational safety and reduces risk.
This article is part of a three-part series about safety beam sensors:
#2 – Why I Recommend Two Beams for Swing Gates
