There has been a study from electricians over on RGP. Forgot which guys did it, but they actually measured the amp draw of all pins...EM's, Solid State, and DMD's and the safe number for amps per game is 2.5A. So on a 20A circuit, following the 80% guideline, you can put 6 pins on a circuit. I am finishing my basement now and I set up 4 20A circuits for the pins. They are spaced around the room so each bank of pins will be on it's own circuit. I host league and parties every once in a while so I need to make sure they can all be on and played at the same time with no issues. The way I see it, more circuits is better especially if you are the one doing the construction....easier to add circuits without drywall than run them later.