Kidde VM-1 Technical Reference Manual

Chapter 7: Service and troubleshooting
P/N 3101890-EN • REV 006 • ISS 21JUN18 149
Figure 47: Wiring short on the loop
(1) Loop controller
(2) Wiring short
(3) Devices in trouble
To isolate the short, open the loop at a point that will disconnect approximately 50% of the installed devices, as
shown in Figure 48.
Figure 48: Isolating a short on the loop
(1) 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 from the loop controller and repeat the analysis. If during the first
process no devices restored, open the loop at a location electrically closer to the loop controller, and then repeat
the analysis. Continue increasing or decreasing the number of devices on the opened loop leg until you isolate
the device or wire segment causing the problem.
Distinguishing short circuits from off-hook conditions in telephone risers
If local regulations require the ability to distinguish between a short circuit and an off-hook condition in a
telephone riser, you must configure the circuit so that it functions as a four-state telephone. Compatible riser
selector modules and telephone sets are listed below.
• GSA-CC1 riser selector
• GSA-CC1S riser selector
(3)
(2)
(1)
(3)
(1)
(2)
(5) (4)

Kidde VM-1 Specifications

General

Brand	Kidde
Model	VM-1
Category	Fire Alarms
Language	English