What is the maximum allowable resistance for grounding systems?

The correct answer is that the maximum allowable resistance for grounding systems is 25 ohms or less. This standard is essential for ensuring that electrical grounding systems are effective in dissipating fault currents safely into the ground. By maintaining a resistance level of 25 ohms or less, the system can minimize the risk of electrical shock and equipment damage during fault conditions.

Grounding systems are crucial for protecting personnel and equipment from electrical hazards, and adhering to this resistance limit helps to ensure that the grounding is adequate to perform its safety functions. Ground resistance impacts how well a grounding system can manage stray voltages and provide effective fault current paths, thus enhancing overall safety in electrical installations related to explosive materials. Additionally, lower resistance values can lead to increased effectiveness in preventing electrical disturbances and ensuring reliable operation of electrical equipment.