Martindale cmi210 ac dc trms insulation clamp multimeter martindale cmi210 p the martindale cmi210 is a unique insulation clamp meter for the installation testing and maintenance of domestic and industrial installations the high specification clamp meter can perform insulation tests to 6g omega with 5 test voltages from 50v to 1000v p p the clamp provides true rms measurement of ac current up to 1500a and ac voltage to 750v it will also measure dc current to 2000a and dc voltage to 1