AEMC 4630 [2130.44]  4-Point Digital Ground Resistance Tester w/ Rechargeable Battery Pack. The Digital Ground Resistance Tester Model 4630 performs ground resistance and soil resistivity tests. This direct reading tester measures from 0 to 2000Ω, and is auto-ranging, so it automatically seeks outs the optimum measurement range. The Model 4630 is rugged, easy-to-use and is ideal for maintenance crews performing numerous tests. It exceeds mechanical and safety specifications for shock, vibration and drop tests specified in IEC standards. It is designed to reject high levels of interference, so it can be used under difficult conditions such as high stray currents that normally affect accuracy. The Model 4630 is powered by 9.6V, 3.5 Ah NiMH rechargeable batteries. A built-in recharge circuit, powered from 120/230V 50/60Hz line, also provides for testing while recharging.