Measure Earth Resistance (20/200/2000 ohm ranges) Measures Earth AC Voltage to 200VAC (40 to 500Hz) Timed function test turns output off after a 3 to 5 min continuous test 2mA Measuring current measures resistance without tripping circuit breakers Data Hold Small Light Weight Auto Power Off IEC 1010 CAT III 200V / CE Included: Test Leads, Auxiliary Earth Spikes, Carrying Case and Batteries 1-Year WarrantyThe model 309 Digital Earth Resistance Meter (Earth Ground Meter) is a small, compact, battery powered, professional meter. This easy-to-use meter is invaluable to electricians and contractors who need to ensure the "ground" quality and effectiveness of buildings, structures, equipment or electrical systems. A good earth ground is required for new buildings or structures needing to pass required electrical codes. Older buildings can lose a good, effective earth ground connection over time. This can happen after a building or structure has been struck by lightning.