Installation manual
  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. 










