According to reprap.org under the title "
Choosing a Power Supply for your Reprap project" its written :
"5 stepper motors, each run at up to 1.2A @ 4V peak per phase = 5 * 4 * 1.2 = 24W, times 2 to allow (conservatively) for driver losses and back emf during movement = 48W"
So my main question is
why multiplying by 2? why not 1.5 or maybe 3? is there a certain standard used here or what?