Voltcraft clip on ammeter adaptor voltcraft vc 511 p the clamp meter in combination with a voltmeter with a millivolt testing range mv enables the measuring of current in an electrical conductor the clamp meter identifies the electrical field that surrounds a current carrying conductor at the output a voltage is distributed that is in proportion to the current p p the vc 511 is designed for alternating and direct current dc the output voltage is alternating or direct current depen