Chauvin Arnoux MN82 [P01120452] 0.5mA to 40A AC Current Clamp. The AC Current Probe Model MN82 is designed specifically for use with the Chauvin Arnoux Ground Resistance Tester Model CA 6471 and CA 6472. When a single probe is used in conjunction with the traditional Fall-of-Potential method, selective grounds can be measured by moving the probe from point to point around the grounding system. When two MN82 probes are used in conjunction with the Model 6471 and 6472, grounding electrodes can be measured without the necessity of installing auxiliary rods and conducting a Fall-of-Potential measurement. This is also referred to as the stakeless method.