Chauvin Arnoux F404 [P01120944] 1000A AC / 1500A DC TRMS Clamp Meter. he Chauvin Arnoux F404 deals with the highest level of low-voltage electrical installations, it has a high protection rating and is ideal for maintenance, testing, monitoring and diagnostics on medium-power installations. Equipped with a fast 12-bit TRMS digital acquisition system, F404 clamps offer particularly accurate measurements whatever the signal's waveform.