The 4 modules selector switches are designed for DIN rail installation in enclosures or cubicles. The voltmeter selector switch uses a single voltmeter for successive measurement of the voltages (phase-to-phase and phase-to-neutral) of a three-phase circuit. Electrical durability of 1,000,000 operations, and mechanical durability of 2,000,000 operations for an utilization category type AC21A-3. This product is calibrated for 440V AC network. 7 contacts for phase 1, 2, 3, phase 1 to neutral, phase 2 to neutral, phase 3 to neutral or none. Complient to standards IEC/EN 60947-3. Ingress Protection IP66 on front, and IP20 on the back at terminal level. Product dimensions are 60mm in height, 36mm in width and 75mm in depth.