the des-1008 switch can be used with ac power sources 100 - 240 vac, 50 - 60 hz. the power switch is located at the rear of the unit adjacent to the ac power connector and the system fan. to turn the switch on, press the power switch to the on or "1" position. the switch's power supply will adjust to the local power source automatically and may be turned on without having any or all lan segment cables connected.