Which measurement indicates a requirement for corrective action in grounding?

A resistance measurement higher than 25 ohms indicates a requirement for corrective action in grounding. In grounding systems, the objective is to ensure that the ground has a low resistance path to facilitate safe operation and effective fault current handling. A higher resistance means that there may be insufficient or ineffective grounding, which can result in an inability to safely dissipate electrical faults.

Standards, such as those outlined in the National Electrical Code (NEC), typically specify a maximum allowable ground resistance to ensure that the grounding system performs effectively under fault conditions. Exceeding the threshold of 25 ohms often suggests that the grounding system may not provide adequate protection against electrical shock or equipment damage, necessitating corrective measures such as improving the grounding electrodes, enhancing soil contact, or adding supplementary grounding methods.

The other options do not indicate a clear need for corrective action. Resistance lower than 15 ohms is generally desirable for a grounding system, while voltage drops above 10 volts and load exceeding 100 amps might indicate other electrical issues but do not directly relate to the effectiveness of grounding performance.