Controlled Products Systems Group 222X383 - Manual (Page 44)

Installation and Maintenance Manual
36
D0119, Rev. F
Detector Loop Installation
Detector Basics
The vehicle detector passes a small current flow through the “loop” which then becomes an inductive coil.
When a vehicle passes over a loop the detector senses the resultant drop in the inductance, and actuates the
detector output.
Loop Configurations
Configurations differ depending on the application. In parking applications with our HTG 320 operator, a loop
may be as small as 4’ x 6’. In traffic applications employing one of our sliding gate operators, or swing gate
operators, the smallest loop should not be less than six feet square.
Rules to Follow for Security Gate Applications
1. The side of the loop closest to the gate shall be located at least four (4) feet distant from it’s line of travel.
2. The shortest side of the loop shall be between six (6) and eight (8) feet in length. The longest side of the
loop shall be between six (6) and twenty (20) feet in length. For applications that need to span a wide area,
use several smaller loops. Do not exceed a maximum of 200 square feet of loop area to only one detector.
3. In applications with multiple loops, keep each loop at least six feet apart. This avoids “cross talk”. It is
possible to have loops closer together by selecting different frequencies. An advantage of using HySecurity
model HY-5A detectors is that problematic “cross talk” is not possible.
4. For greater sensitivity and less chance of false calls caused by the motion of the gate, it is better to use
multiple smaller loops, connected in a series circuit, to one detector instead of one large, single loop.
5. To avoid interference, keep loops at least two (2) inches above any reinforcing steel. Do not route loop wires
with, or in close proximity to, any other conductors, including other loop leads, unless shielded lead-in cable
is used. Never route high voltage circuits in PVC conduit near a loop.
6. Loop and lead-in wire should be one continuous piece. Avoid splices, if possible. If a splice is necessary for
any reason, “pot” the splice in epoxy or use heat shrink to ensure that the quality of the splice covering is the
same as the original wire jacket.
7. Use only number 14, 16, or 18 gauge stranded wire with a direct burial jacket. Cross linked polyethylene
insulation types, such as, XLPE or XHHW, will last much longer and are less prone to damage during
installation than conventional insulation types. Preformed loops can be used before road surfacing or under
pavers.
8. Twist loose tails of lead-in wires tightly, approximately ten times per foot.