Quoted from MarkG:
I can't answer your specific question, but keep in mind that the worst case current draw is likely to be when the game is first powered on. It's called the inrush current and can be several times the normal current draw which may account for the 8 amps on the label vs the 2-3 amps observed. So if you're going to turn games on one at a time your worst case current will be much lower than if you have switched outlets (which I highly recommend BTW) to turn several games on simultaneously.
Yeah, I have a kill switch on my electrical outlets circuit in plain sight but I don't use it to turn the games on/off. I turn them on individually for the reason you state.
When I have a bunch of people over and the house is all lit up in most rooms and the 28 games will be lit up and many of them in simultaneous play, I've had the breakers break and the house go dark. So, before the party starts, what I do now is tape black electrical tape over the light switches anywhere in the house that is on the same circuit(s) as the pinballs, so guests know not to flip them on, and I light up the house using different circuits. Haven't had a problem since.