FLUKE 323 Voltage Clamp Meter CAT III 600V, CAT IV 300V. The Fluke 323, 324 and 325 are designed to perform in the toughest environments and provide noise-free, reliable results to diagnose problems. True RMS measurements and optimised ergonomics make the 320 Series the best and easiest-to-use general troubleshooting tools for commercial and residential electricians.