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Loops
Other Loop Detector Facts
1.
Always clean saw cuts thoroughly with water, air or brush to remove all debris prior to installing wire.
2.
Recommended loop wire is TFFN #16 gauge stranded wire. It is available at electric supply
distributors.
3.
No splices are permitted in the loop or loop leads. One continuous wire should be used.
4.
Lead wires should be twisted a minimum of 4 twists per foot to eliminate false sensing. Twists should
begin at the edge of the loop and continue to detector.
5.
Do not use metal or sharp objects to push the loop wire into the saw cut. The slightest nick or cut in the
insulation will cause the loop to ground out and malfunction. To test for shorts, use a megohmeter or
"Megger" between either loop lead and earth ground with both leads disconnected from the detector.
The resistance should be greater than 50 megohms.
6.
Use siliconized caulk for backfill. Gray for concrete, black for asphalt. 25-Year life rating is preferred.
7.
Never set adjacent loops on the same frequency. False activation will occur.
8.
Almost all brands of detectors have an external or internal sensitivity adjustment. Usually the factory
setting is sufficient if internal adjust type. Be very careful and use extreme caution when decreasing
sensitivity.
9.
Most false activations are caused by an improperly installed loop or a shorted loop. The loop should be
tested and validity determined before adjusting sensitivity. See # 5 above.
10.
Most detectors used in the gate business are fail-safe. This means that if the loop fails, the gate will be
given a continuous signal. When power is disconnected from a detector, the signal output is also given.
11.
ASB, or automatic sensitivity boost is now available on most detectors. This feature should be
activated if large truck or trailer traffic is likely.
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