Figure 3-4. Effect of an Unbalanced Cable on the Single-Point Ground

Custom Search

Back
Figure 3-3. Use of Balanced Lines to Avoid Ground Loops

Up
Grounding, Bonding, and Shielding for Electronic Equipments and Facilities

Figure 3-5. Effect of Arbitrarily Grounding the Source End of Unbalanced Equipment Interconnecting Cables

MIL-HDBK-419A

Multiconductor cables which contain unshielded or individually shielded wires, or both, frequently

have an overall shield provided for both physical protection and to provide supplemental electromagnetic

shielding. Such overall shields should be grounded at each end of the cable run to provide a continuous rf shield

with no breaks.

For long cable runs where the cable is routed through one or more intermediate connectors, the

overall shield should be grounded to the frame or case of junction boxes, patch panels, and distribution boxes

along, the cable run.

For maximum shielding effectiveness, the overall shield should be effectively bonded as shown in

Figures 3-7 and 3-8 with a low impedance connection to the equipment case, enclosure wall, or other

penetrated (metal) shield. The best way to bond the overall shield to a connector is to run the shield well inside

the connector shell and provide clean metal-to-metal circumferential contact between the shield and the shell.

If the connector is not involved, shortest practical lengths of connecting strap or jumper should be used.

Figure 3-4. Effect of an Unbalanced Cable on the Single-Point Ground

3-8