[Jim Becker]

Um..m the spindles are 3 phase. (except for the one tiny 1.0kw option) That's how they work. But the power requirement from the wall is single phase unless you have a really big machine that has horsepower that requires industrial 3 phase power. The Stinger series use 4 wire 240v circuits from the wall when equipped with the size spindles they support. The VFD converts the single phase power to 3 phase to power the spindle. The rest of the controller is running on 120v power which is why a four wire circuit is required. Ask Camaster for the prep guide for your machine and spindle size.