Certified Data Centre Professional (CDCP) Practice Exam 2026 - Free CDCP Practice Questions and Study Guide

The term CMN, or Common Mode Noise, is generally used in the context of electrical systems to describe the voltage difference that can inadvertently develop between the ground and neutral wires due to various factors like electromagnetic interference or imbalanced loads. A voltage difference below 1V is typically considered acceptable or insignificant, meaning it generally does not pose a risk for most electrical equipment and systems. This low level of voltage difference indicates a stable and well-functioning electrical system where the grounding and neutral systems are properly bonded, and minimal noise is introduced.

In practice, maintaining such a minimal voltage difference is crucial for ensuring the safety and efficiency of electrical installations. When this difference is low, it suggests that the circuit is operating as intended, with minimal risk of malfunction or interference, which is essential for data centers where reliable electrical supply is critical for system operations and data integrity.