If a made electrode fails the ground resistance test, how far must an additional ground electrode be placed from the existing electrodes?

The correct answer is that an additional ground electrode must be placed at least 6 feet from the existing electrodes if a made electrode fails the ground resistance test. This distance is based on standards and best practices in grounding systems, which aim to prevent interference between ground electrodes. Positioning the new electrode at this distance helps ensure that the ground paths do not interact in such a way that could compromise the effectiveness of the grounding system.

Placing the additional electrode too close to the existing one can lead to parallel paths for fault current or hinder proper grounding by not effectively splitting up the grounding system. This adherence to a sufficient spacing guideline is crucial for maintaining low ground resistance levels, especially in critical medical environments where reliable electrical grounding is essential for equipment safety and performance.

Thus, the stipulated distance of 6 feet is a practical measure to enhance the reliability and performance of grounding systems in biomedical applications.