I wasn't implying switching the AC side very quickly. What I was thinking is that indeed most wall supplies are switching regulators which means if you just sit there and switch it on and off on the AC side (let's say once per second) you have the potential to damage it since it was never designed for that. The inrush (charging the primary-side cap) sends a lot of peak current through the rectifiers and they might not like that.
I know we aren't talking about switching motors but you made a generalized statement about switches and I merely pointed out it isn't always the case.
So what your really asking is what current to expect on the AC side of a computer switching supply that you want to turn on and off with out unplugging it. The use of the power supply is to run your Arduino on. It is not to control from the Arduino.
So what you want is a standard remote wired switch for AC line power.
And your concerned for the load on that switch.
As stated your house wiring is either 20A outlet or 15A outlets. Since computer supplies (laptop) are expected to run on a max outlet of 15A any house wiring remote switch will work.
Look for an appliance in line AC switch and it will surely meet your needs.
I use the WEMO WIFI switch as I can use my PC to control it on and off. Also any good remote lamp control switch will work just fine.
Hi all,
An spanish monologist had an story that started with the colonel informing the lieutenat colonel tha a sun eclipse will happen next day: the troop had to be formed and learned what an eclipse really is and, then, provided with adecuate glasses to watch at it; just in case the day was cloudy, there should be an alternative theoretical complementary explanation at the gym.
The Lt. colonel told the mayor that told the captaint that told the lieutenant that . . . that . . .that . . . . Finally the troop was informed that the sun was about to have an eclipse in the gym just in case the rain wasn't expected next week: everybody shoud bring an umbrella tomorrow to protect themselves from sunligth . . . . . . .while making some sport.
Such a similar situation happens frequently in the forum: OP just wanted to know if P(VA)=I(A) * V(Volt) in the AC side same way than P(Watt)=I(A) * V(Volt) in the DC side . . . . . the whole thing has derived in a complete swithching theory . . . .
(Any way, in my opinion this is very healthy . . . . 
. .. is not?)
Regards