Ion Physics Corp.'s CM-001-ES current monitor measures peak current at line frequencies up to 150 kA and rms currents up to 20 kA at 60 Hz. The monitor's air-core design has an inner diameter of 2 in. and an outer diameter of 5 in. When placed around a current-carrying conductor, the CM-001-ES senses the magnetic field and can measure the current without a direct connection. The current signal is converted into a proportional voltage signal that can be read on a scope or voltmeter with a 0.1-mV/A sensitivity.