Ground Fault; Procedure For Isolating Earth Ground Faults; Table 11: Terminal Grouping Ground Fault - Bosch D7412G Installation & Troubleshooting Quick Reference Manual

D9412G/D7412G/D7212G
Troubleshooting
3.16

Ground Fault

If a D9412G/D7412G/D7212G system detects a Ground Fault, considered as a high impedance fault to earth ground of
approximately 100 kΩ or less, the control panel's command center displays SERVC GND FAULT. Use the following
troubleshooting procedure as a general guideline in identifying and isolating the cause of the earth ground fault.
Please read this procedure carefully before trying to identify the cause of the Ground Fault.
IMPORTANT
3. 1 6. 1

Procedure for Isolating Earth Ground Faults

Warning! To prevent personal injury, caution should be observed when identifying whether or not Ground Fault is
on one of the panel power terminals or the Battery terminals. Both are capable of delivering a high current and
have the potential to cause personal damage.
WARNING
1. With this safety measure in mind, the first step is to verify that the Ground Fault is, or is NOT on the Battery
terminals (terminal 4 and terminal 5). This procedure requires the use of a Digital Volt Meter (DVM) and a
13.0 in. (33 cm) Jumper Wire.
As a point of reference: When a D9412G/D7412G/D7212G Panel is not in GROUND FAULT CONDITION, a
voltage reading between terminal 9 and terminal 10 is 6.5 VDC to 6.8 VDC.
2. Place a DVM meter on DC Volts scale, and connect the Positive (red) lead of the DVM to Terminal 10 (Earth
Ground) and the Negative (black) lead to Terminal 9 (Common) of the control panel.
If the voltage reading is between 13.70 and 13.88 VDC, STOP! This voltage reading means that the Ground
Fault may be in one of the Panel power circuits such as the Battery, or AUX.
Remove both battery wires from terminal 4 and terminal 5 at the same time. If the voltage across terminals 9
and 10 changes to 6.5 to 6.8 VDC (which indicates a normal reading), then the ground fault is on the battery
wire (or wires). Locate and remove the ground fault.
If the voltage across terminals 9 and 10 still measures between 13.70 and 13.88 VDC, then reconnect the battery
wire(s) back to terminal 4 and terminal 5 and go to Step 3.
3. If the voltage across terminals 9 and 10 reads 0 VDC, STOP! This voltage reading indicates that the Ground
Fault is on any of the panels' Common terminals. Remove both battery wires from terminal 4 and terminal 5.
If the voltage across terminals 9 and 10 changes to 6.5 to 6.8 VDC, then the ground fault is on this battery
negative side. Locate and remove the ground. If the voltage across terminals 9 and 10 does not change, then
reconnect both Battery wires to terminal 4 and terminal 5 and go to Step 4.
4. With the DVM still connected between Terminals 9 and 10, use the following chart to determine which terminal
grouping has the ground fault.
Voltage at Terminals 9 and 10
0 VDC
approximately 1.7 VDC
approximately 2.5 VDC
approximately 7.0 VDC fluctuating
approximately 7.6 VDC fluctuating
approximately 11 to12 VDC
approximately 13.8 VDC
Note: Terminals 6 and 7 are not energized. Terminal 8 is energized.
D9412G/D7412G/D7212G Installation & Troubleshooting Quick Reference Guide
43700F
Ground Fault on Corresponding Terminal
4, 9, 12, 15, 18, 21, 23 (D9412G only), and/or 29, 6 and/or 7
6 and/or 7
11, 13, 14, 16, 17, 19, 20, and/or 22,
30 and/or 31
1 and/or 2
25 (D9412G/D7412G only), 26 (D9412G only), and/or 28 (see Step 5)
3, 5, 8, 24 (D9412G only), and/or 32

Table 11: Terminal Grouping Ground Fault

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