Current draw on the AC input of a PSU
Cheap PSU may have not power factor corrector. In such case it draws non-sinusoidal current with RMS value which is larger than P/Uin (power per input voltage). Then, input power is larger then output (because of non-unity efficiency). So, even nominal input current is estimated at about 3 A. Taking into account already mentioned large inrush cuurrents, it's a good idea to use 10 A rated switch for long reliable operation. But 3A rated switch may also work for a while :)