Loop Detectors and Loops
Loop Detectors are a device that is connected to a wire loop burred in the center of your driveway. A set of contacts and closes a circuit when a vehicle passes. The detector itself is a small box and has a universal connector (11 pin connector) or operator specific connector (custom connector). Both types of units do the same job. The universal type can be substituted for dedicated units. The dedicated units are convenient because they plug directly into the specific operator they are designed for, thus saving installation time. The detector acts similar to a metal detector in how it functions.

Loops are one of the most common sources of problems in automatic gate systems. Because the wire loops are buried beneath the roadway and are subject to adverse conditions and should be installed carefully. Always use recommended loop wire or loop assembles (pre-formed loops). Make sure connections and splices are in accessible boxes, preferable above grade. It is always a good idea to solder the connections.

Most loop detectors have sensitivity adjustments to accommodate larger high height vehicles. They also have a frequency adjustment. This is used primarily when using more than one detector to prevent RF (radio frequency) interference between the units. Always set the frequency differently when using more than one detector.

The detectors are commonly used to open the gate for exiting vehicles (exit loop) and to prevent the gate from closing on vehicles in its path (safety loops). Sometimes they are used to open a gate from outside as well (entrance loop). An installation may have two-way traffic with a desire to keep the gate closed as much as possible, such as keeping farm animals in. Another common scenario for an entrance loop is a gate that opens automatically upon entry, but is time controlled to prevent entry after hours. In that scenario the entrance loop detector is connected to a seven day timer.

Wand type vehicle detectors are an alternative that can be used as a vehicle exit detector. It is not recommended that they be used as safety detectors (safety loops). These are not recommended on wide roads, (no wider than 14’) due to their limited detection range. These units are buried shallowly by the side of the road and offer ease of installation. They come as fully self contained (single unit) and with detector/wand option (two piece). The two piece units offer the same options as regular detectors with frequency and sensitivity adjustments.