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Loops
Loop Size Chart
The loop size is based on the width of the driveway. If the driveway is 14' wide, the loop would be a 6'x6', the
minimum. This is determined by subtracting 4' off of each side of the drive, which would leave you 6'.
See chart below for number of turns per loop size, plus lead in.
The loop itself should contain between 90 & 125 feet of wire in the loop, plus lead in.
Number of Turns Per Foot
Drive Width
Loop Size
2 3 4
14 feet and under
6’ X 6’
96’
16 feet
6’ X 8’
112’
18’
6’ X 10’
96’
20’
6’ X 12’
108’
22’
6’ X 14’
120’
24’
6’ X 16
132’
26’
6’ X 18’
96’
28’
6’ X 20’
104’
30’
6’ X 22’
112’
32’
6’ X 24’
120’
The location of the loop is also important. If a loop is located too close to the gate, it will detect the gate itself, giving
false operation. If the loop is too far away from the gate a small vehicle might not be detected. Loops should be
about 5' from the centerline of a gate when closed. See Loop Position on previous 2 pages.
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. 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 megohm meter 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 silicon 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.
Some brands of detectors have an external or internal sensitivity adjustment. Usually the factory setting
is sufficient on internally adjusted type detectors. On externally adjusted types 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 if available should be on if large truck or trailer traffic is likely.
