What is the ideal maximum resistance of an electrical ground for effective performance?

The ideal maximum resistance of an electrical ground for effective performance is typically considered to be 25 ohms. This standard is often referenced in various guidelines and codes to ensure that grounding systems can effectively dissipate fault currents and provide safety for electrical systems and personnel.

A lower resistance value is generally preferred as it improves the grounding system's ability to conduct fault current, reducing the risk of electric shock and equipment damage. However, 25 ohms is viewed as a maximum threshold where the ground is still functioning adequately in most residential and commercial applications.

Grounding systems with resistance above this level can become less effective, potentially allowing voltages to rise to unsafe levels during a fault condition. Therefore, establishing a grounding system with a resistance of 25 ohms or less helps promote safety and reliability in electrical installations.