Martindale cm79 600a ac dc true rms trms clamp multimeter martindale cm79 p the martindale cm79 is a pocket sized high performance trms ac dc clamp meter measuring both ac and dc current up to 600a as well as ac and dc voltage plus resistance with a continuity test function its compact rugged design enables accurate and reliable dc current measurements down to 10ma resolution in applications including photo voltaic pv installations battery monitoring and electric vehicle maintenance