Wallace Perimeter Security SPEEDGATE, Installation And Maintenance Manual

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INSTALLATION INSTRUCTIONS FOR OPTIONAL VEHICLE DETECTORS
Installation of Vehicle Detection Ground-Loop Systems
8. If an automatic exit loop is required, a third detector relay will be required. If an automatic
exit loop is required, a third detector relay will be required (not supplied by Wallace Perimeter
Security). This auxiliary detector should be powered from terminals #1 and #2 and wired as a
N.O. contact to terminals #1 and #3.
9. Choose a sealant carefully to match the application and the pavement type. Hard setting
epoxies should not be used with asphalt. Caution should be observed when using hot sealants,
as high temperatures can damage or destroy wire insulation. Please refer to the jurisdiction/
state’s department of transportation specs for traffic light loop sealant.
9.1 When properly applied, the sealant should completely cover the loop wire(s). Since the sealant
forms a barrier between the wire and the environment, it is essential that the wire(s) are
completely covered. See Figure 20 for the proper end result.
9.2 There MUST be no voids which might allow water to collect within the slot. The water will
freeze and expand during freezing conditions. Freeze/thaw cycling will eventually push the
loop wires up and out of the slot, resulting in a loop failure.
10. Loop Diagnostics
The following tests cannot guarantee a functioning loop, but failure of either test means that
the loops are definitely suspect, even if still functional at the time of testing.
10.1
TEST 1
- Resistance of the loop and loop lead wires should not exceed 4.0 ohms.
10.2 TEST 2 - The resistance to earth, as measured with a 500V “Megger”, should be 100 Megohms
or more. Loops may function at less than 100 Megohms but will not be reliable (e.g., when the
ground is wet from rainfall). Low resistance indicates broken or moisture-saturated insulation.
This is common if inappropriate wire insulation has been used.
Figure 20. Proper Sealant Application