It's good to be grounded. Structures with properly grounded electrical systems are critical to the safety of people and equipment, giving current from a lightning strike or utility overvoltage a safe path to earth.
Whether simple or complex, grounding systems require periodic testing to ensure their readiness. The International Electrical Testing Association specifies ground electrode testing every three years, though annual inspections are often recommended as part of routine facility maintenance plans.
What to look for: Corrosion in ground rods and their connections due to exposure to moisture, salt and fluctuating temperatures. A year-to-year increase in resistance of 20 percent is a red flag and should be investigated.
In an ideal world, a ground should provide resistance of zero ohms (0 Ω). No standard for a ground resistance threshold is recognized by all agencies, though the National Fire Protection Association and the institute for Electrical and Electronics Engineers have recommended ground resistance of 5.0 ohms or less. That figure is also widely accepted within the telecommunications industry.
Fluke's assortment of earth ground testers addresses the spectrum of ground testing methods, featuring high-quality tools engineered accuracy, safety and ease of use.