PAL-AT Installation Manual
21
Figure 4-1
Typical Cable Connection in Monitored Areas with Junction Boxes
4.2 Calibration Points
1. During the initial setup and calibration of the PAL-AT system, connectors at selected locations
(calibration points) are temporarily disconnected. Therefore, it is imperative to have accessibility
to connectors at calibration points at all times until the system is brought on-line.
2. Reported fault location accuracy of the first leak is dependent upon the use of and distance between
calibration points. Calibration points are required at changes of cable types unless connected to short
lengths of jumper cable (15' [5 m] or less). Additional calibration intervals of 500' [150 m] or less will
result in location accuracy of within +/- 6' [2 m]. Systems installed with calibration intervals exceeding
500' [150 m] will have a location accuracy of less than +/- 1% of the cable length from the previous
calibration point.
4.3 Junction Boxes
There are two series of junction boxes supplied by PermAlert. The standard, polyester box has a
maximum temperature rating of 150°F [65°C]. A fiberglass box is available for temperatures to 300°F
[150°C].
1. Locate and install all junction boxes before installing any cable. Locate junction boxes as indicated on
system drawings or as required. These locations include calibration points, the start and end of cable
runs, manholes, probes, etc. Care must be taken to prevent water from contaminating these areas.
2. Securely mount the junction boxes to a vertical wall. In manholes or pits that might collect and hold
water, mount junction boxes as high as possible. Use NEMA 4X [IP66] junction boxes at all locations.
3. Use a hole saw to cut the junction box as needed for conduit.
4. When jumper cable is installed in electrical conduit, use watertight conduit hubs and cord grips at
junction boxes. Discard the male bushing supplied with the hub and use the cord grip supplied in its
place. Depending upon the specific products used, a lock nut may be required on the cord grip's
threads to pull the hub tight to the wall of the junction box.
Caution: Always keep junction boxes and electrical conduits capped to prevent water from
entering.
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