Emi On Long Wire Runs; Checking Shielded Cable; Battery And Power Reports - Bosch D7412G Installation & Troubleshooting Quick Reference Manual

D9412G/D7412G/D7212G
Troubleshooting
3.9

EMI on Long Wire Runs

EMI (ElectroMagnetic Interference) can cause problems on long wire runs for serial devices (command centers, POPITs,
etc.). The use of shielded cable reduces the effect of this interference. Some potential sources of noise on a long wire run
include:
• Radio or television transmitter site.
• Ham radio operator's transmitter site.
• Computer network system.
• Heavy machinery (large electrical motors).
• PBX telephone system.
• High voltage electrical equipment or transformers (arc welders, certain medical and dental equipment, etc.).
• Public service office using radio communications (fire department, police department, etc.).
• Close proximity to electrical lines, telephone cabling, or fluorescent lighting fixtures.
There are many other possible sources of noise. If noise may be a problem, the use of shielded wire is strongly
recommended. Connect the drain wire from the shielded cable to Terminal 10 on the panel.
The drain wire must have continuity from the panel to the last device on the wire run. If the cable is cut to install devices
between the last device and the panel, be certain to reconnect the drain wire to insure continuity to the last device.
If continuity is not maintained between the panel and the last device, the shielded cable may aggravate potential noise
problems rather than eliminate them. Connecting the drain wire to ground at other than Terminal 10 on the panel may also
produce problems. Do not connect the drain wire to any other ground source.
3.10

Checking Shielded Cable

If improperly installed, shielded cable can create problems rather than solve them. Follow the procedure below to check
shielded cable for proper installation:
1. Remove the drain wire for the shield from Terminal 10.
2. Meter the drain wire for continuity to Terminal 10 (earth ground). If there is continuity, find and remove the
foreign ground on the drain wire.
3. Reconnect the drain wire to Terminal 10.
4. Meter the shield at the far end of the cable (last POPIT location on data expansion loops) for continuity to a
ground reference. If there is no continuity, find and repair the open in the shield. Solder and tape all
connections.
3.11

Battery and Power Reports

The panel can be programmed to transmit both battery and AC power status reports. Refer to the panel's Program Entry
Guide. If battery or AC power reports are a problem check the following:
1. Check to be sure the panel's power supply is not overloaded. Review Section 2.0 Quick Reference Terminal
Description on page 7 and Section 3.14 Overloaded Power Supply on page 17.
2. Verify that there is at least 16.5 VAC on Terminals 1 and 2.
3. The outlet the transformer is plugged into should meter between 110 VAC and 120 VAC.
4. Verify the output for the transformer connected to Terminals 1 and 2 is rated for 16.5 VAC and at least 40 VA.
5. Disconnect the transformer from Terminals 1 and 2 and meter the battery at Terminals 3 and 4. A fully charged
battery will show approximately 13.8 V.
6. Make sure the battery is a 12 V sealed lead acid type. It should be rated at 7 Ah or greater, depending on the
NFPA classification of the installation.
7. If it takes longer than 60 sec. to detect a missing battery, make sure there is a good earth ground connection.
Also check that there are no external devices that may be inducing voltage.
D9412G/D7412G/D7212G Installation & Troubleshooting Quick Reference Guide
43700F Page 16 © 2004 Bosch Security Systems, Inc.