Chapter 7: Service and troubleshooting
EST3X Technical Reference Manual 201
Short circuit conditions
Short circuit conditions require selective isolation of portions of the loop to
systematically narrow down the fault’s location. A shorted circuit typically reports
to the control panel a trouble condition on all devices, as shown in Figure 50.
Figure 50: Wiring short on the data loop
(1) Signature loop controller
(2) Wiring short location
(3) Devices in trouble
To isolate the short, open the data loop at a point that will disconnect
approximately 50% of the installed devices as shown in Figure 51.
Figure 51: Isolating a short on the data loop
(1) Signature loop controller
(
2) Open in loop to isolate the short
(3) Wiring short location
(4) Devices remain in trouble
(5) Devices return to operation
After opening the loop, if some of the devices restore, the short is located on the
portion of the loop that has been disconnected. If no devices restore, the short
has been isolated to the first 50% of the loop.
Reconnect the previously isolated portion of the loop. If during the first isolation
process some devices restored, open the loop at a location electrically farther
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