2 = Mains switch ON / OFF (In standby mode - switch on “I”, the AC power voltage is present within the instrument, even if the apparatus is switched off by the push button on the front)
3 = Mains Input (blue) 120 / 230 V, 50/60 Hz no switching of voltage necessary (Cable not included ex works)
4 = Mains Output (grey) 120 / 230 V, 50/60 Hz no switching of voltage necessary (Cable not included ex works)