The I400S is an AC current clamp designed for non-invasive measurement of alternating current in circuits up to 1000 V CAT III or 600 V CAT IV. It features dual measurement ranges: 0.5 A to 40 A with 10 mV/A output, and 5 A to 400 A with 1 mV/A output, providing accuracy of 2% + 0.015 A (40 A range) or 2% + 0.04 A (400 A range) across 45 Hz to 400 Hz. The clamp is compatible with any instrument featuring BNC or banana inputs with input impedance greater than 1 MO in parallel with up to 47 pF, and includes a 2.5 m output cable with maximum conductor size accommodation of 32 mm. Operating over 0°C to 50°C with a typical bandwidth of 5 Hz to 10 kHz, the I400S is ideal for field maintenance, troubleshooting, and electrical system diagnostics where safe, non-contact current measurement is required.