A vehicle detection loop is specially insulated wire laid in a circular or rectangular pattern that is either buried beneath the driveway or cut into the concrete or asphalt. The wire is coiled or turned several times to create a magnetic field when low voltage current is drawn through it. When a vehicle drives over the loop, it senses the vehicle and triggers a relay in the loop detector housed in the gate operator.
Loops can serve many different functions. Some common roles they play are:
- Reversing Loop: Located approximately 4’ inside and outside the moving gate. These loops prevent the gate from closing on a vehicle by reversing back open or holding the gate open until the vehicle is out of range of the loops.
- Shadow Loop: The arc of a swing gate is outside the range of the reversing loop. This loop holds the gate open until the vehicle is out of the way of the gate.
- Exit Loop: An exit loop is installed inside the property typically 20 feet or so from the gate. As a vehicle passes over it, the loop directs the gate open. No transmitter, keypad or other control device is required. Not only is this convenient for the homeowner, this is important for properties where visitors will need to exit through the vehicle gate.
- Exit loop for free entrance: When security is not important, an outside reversing loop can be used as an “entrance” loop.
- Specialty Loops: Loops can make other things happen as well…turn on or off lights, allow transmitters or key pads to work, trigger an alarm or a camera…any event a customer wants to take place when a vehicle’s presence or absence is detected.
Loops are a weak spot in many gate systems. All loop connections must be soldered and any underground connections completely waterproofed in order to avoid problems. The size, shape, number of turns of wire in the loop and its overall age and condition will determine its sensitivity.
Bay Cities Automatic Gates installs its own loops and is very exacting in both the performance and the aesthetics of the loops. Checking the condition of loops is an important procedure during our preventive maintenance visits.
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Bay Cities Automatic Gates • 853 Suite C, Industrial Road • San Carlos, CA 94070 • 650.595.4283
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