There is no need to power any switch motors from the track, and operationally (even conventional) it's a bad idea, because you can't throw switches with track power off or low. Simply feed the controller with a wire from the transformer ground (usually "U") and connect the center switch motor terminal to an accessory circuit. The advantage is that, with a DZ motor (but not with a stock NJI motor) you can easily add a non-derailing feature.