Interlogix NX-8E Installation Manual - Manual (Page 67)

Chapter 3: Reporting codes
NX-8E Control Panel Installation Manual 63
Voltage tables
The following tables show normal values for control panel voltages. if these
values are incorrect, you may experience trouble or fault conditions.
Table 11: Phone or power voltage values
Phone or power voltage Value
T to R and T1 to R1 50 VDC not communicating (on hook)
T to R 7 VDC communicating (off hook)
T1 to R1 0 VDC communicating (line seized)
AC to AC 17.5 VAC
Data to common 6 VDC nominal (1.5 to 10 V, fluctuates)
Keypad positive to common 13.5 VDC
Aux power to common 13.5 VDC
Battery to battery 13.5 VDC
Table 12: Zone voltages (

10%)
Zone condition Value
Zones, not doubled
Open 13 VDC
Good (3.3 kohm resistor) 6.6 VDC
Shorted 0 VDC
Two-wire smoke (680 ohm resistor) 10.75 VDC
Zones, doubled
Open 13 VDC
Only low zone OK (3.74 kohm resistor) 7 VDC
Only high zone OK (6398 kohm resistor) 9 VDC
Both high and low zones OK 5.5 VDC
Shorted 0 VDC
Normally open zones (such as four-wire smoke) Use low zone resistor (3.74 kohm resistor).
Cannot use the corresponding high zone.