GPS1195 Auto Gate Manual Version 3
Loop Installation
1)
Loop geometry will depend on the particular requirements of the installation. Generally for
most parking control applications can be satisfied using a standard 2 ½’ x 6’ PVC or a saw cut
loop.
2)
If a single loop is used with a long lead in cable (500ft or more), it is recommended to add an
additional turn in the loop. This will increase the ratio of the loop inductance to the total
inductance, thereby improving loop sensitivity and overall system stability.
3)
When selecting loop geometry for a specific application always design the loop network with an
inductance range of 100 to 250 microhenries.
4)
All connections associated with the loop circuit (loop and loop leads) should be either soldered
or crimped with a tool that will ensure a good and tight connection. Do not use wire nuts.
5)
The loop leads and loop turns should be a continuous length of wire with no splices. The loop
should be twisted approximately three turns per foot back to the detector. If long lead in
distances makes this impractical, a pull box should be located at the side of the street in which
loop leads should be spliced to a twisted shielded (Belden 8719, 8720 or equivalent type) and
the pull box sealed against moisture. The shield of the cable should be connected to earth
ground at the detector only. If splices are necessary, connect as in 4 above and waterproof
6)
All steel beams, Iron drains, Water pipes, etc. should be at least 12 inches away from detector
loop area (including loop leads). Loop wires must be installed a minimum of four inches above,
never below metallic objects (e.g. Reinforcing bars). Metallic objects running at right angles to
the loop wires have a less effect when running parallel to loop wires. All power and control
wires must be a minimum of 24 inches from the detector loop. Only the loop wires are to be run
in the conduit. All other wires are to be run in a separate conduit(s). Never install loops within
ten feet of underground de-icing systems.
7)
Install loop leads in PVC type conduit only.
8)
The loop on one side of a slide / swing gate or door and connected to its own detector must be
set back from the gate or door a minimum distance equal to 25% of the length of the side of the
loop facing the gate or door or 3ft, whichever is greater. This will prevent the detection of a
moving gate or door.
9)
It is not recommended to install loops in gravel or under paving stones. Do not install loops in
areas that cross expansion joints. Road surfaces must be stable, in good repair (no cracks, holes,
etc.) and constructed with proper base support and drainage.
10)
PVC loops should be installed two to three inches and not more than five inches below the
surface.
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