What is the recommended grounding approach to minimize noise and interference in instrumentation?

• A. Use a single-point ground
• B. Do not bond cabinets
• C. Tie every device directly to earth ground at different points
• D. Create multiple ground paths

Answer: (A)

Grounding for instruments aims to provide a clean, consistent reference point. The recommended approach is a single-point ground (often implemented as star grounding), where every device returns to the same low-impedance ground node. This keeps the ground potential the same across the system and minimizes the paths for return current, reducing the chance that grounding currents create voltage differences on signal or shield paths.

When there are multiple ground paths, ground loops can form. Different equipment can sit at slightly different ground potentials because current flows through various grounding conductors, and that differential voltage can couple into measurement signals, adding noise and hum. Bonding cabinets or tying devices to earth at different points deliberately creates those multiple paths and increases loop area, inviting interference. So a single-point ground minimizes loop currents and keeps signal integrity at its best.