Noise Coupling Mechanisms

DOE-HDBK-1092-98

2. Coiling the extra length on a 6-inch diameter (about 12 turns).

3. Securing it tightly wound with cable ties.

4. Connecting it into the circuit.

These actions satisfy the NEC requirement for a continuous ground and noise isolation is also

enhanced.

Whatever scheme is used, the ground of experimental equipment shall be connected to the same

ground as the facilities' electrical system to ensure equal potential.

For practices involving hazardous materials, such as explosives, the grounding shall also comply

with the requirements of Section 5.0, "Special Occupancies".

10.9.2.1.3 NOISE COUPLING MECHANISMS.

Grounding can reduce the interference in the five types of coupling mechanisms listed here.

1. Conductive Coupling. (Source and load wired together) It is sometimes practical to provide

a separate return path for both the source and the load. If the system layout allows this, then

conductive coupling cannot occur between these two, as is shown in Figures 10-2 and 10-3.

Process Power Cable

Process

Power

Supply

arc

I arc

Existing Ground

Frame

Process

Safety wires

Enclosure

Conduits

Wireway

Process

Control

Control/Instrument Lines

CONDUCTIVE COUPLING SITUATION

Figure 10-2. Arc currents through the process power supply return (existing ground) develop a voltage that

appears in series with the process controls because they share that return.

10-15