If you are talking about em games it is pretty simple. Gottlieb em schematics from the 70s have the power consumption printed on them. Some examples are: Big Brave 126 Watts, Pioneer 149 Watts, Royal Flush 150 Watts. These figures equate to 0.525 Amps, 0.621 Amps and 0.625 Amps at 240 volts. So pinnies don't draw much at all. I cant see that electronic machines would be much different.