Controlled Products Systems Group SLIDESMART DC 10F - Manual (Page 104)

Installing Vehicle Detectors and Loops
6-6 SlideSmart DC Installation and Reference Manual Revision D
I
NSTALLING
V
EHICLE
D
ETECTORS AND
L
OOPS
A vehicle detector passes a small current flow through the “loop” which then becomes an inductive coil. When
a vehicle passes over the 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, a loop may be as small as
4 x 6 foot (122 x 183cm). In traffic applications employing one of our swing or slide gate operators, the
smallest loop should not be less than 6 x 6 foot (183 x 183cm) in order to detect high bed vehicles.
Rules to Follow for Security Gate Applications:
The side of the loop closest to the gate must be located at least 4 ft from the line of travel.
1. The shortest side of the loop should be between 6 and 8 feet (1.8m and 2.4m) in length. The longest side
of the loop should be between 6 and 20 feet (1.8m and 6.1m) in length. For applications that need to span
a wide area, use several smaller loops. Do not connect more than 200 square feet (18.6sq. m) of loop area
to a single detector.
2. In applications with multiple loops, keep each loop at least 6 feet (1.8m) 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.
3. 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 a single large loop.
4. To avoid interference, keep loops at least 2-inches (5cm) 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.
5. 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.
6. Use only 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.
7. Twist loose tails of lead-in wires tightly, approximately ten times per foot. See Figure 6-5.
8. Follow this guide for the correct number of turns in the loop;
12 to 20 sq. ft = 5 turns; 20 to 60 sq. ft. = 4 turns; 60 to 240 sq. ft. = 3 turns
3.7 to 6.1sq. m = 5 turns; 6.1 to 18.3 sq. m = 4 turns; 18.3 to 73.1sq. m = 3 turns
Figure 6-5.
Twist lead-in at least 10 turns per foot
Like This Not Like This
Twist Like This