Flush - If you use a 240V photo control on at 240V fixture you do not need a neutral. The voltage rating of the photo control is the rating of the heater that controls the bi-metal switch. Most manufactures have 120V rated photo controls and 208V - 277V rated controls. As far as I know all of them have black, red and white leads. The black is line, red is the load and the white gets connected to the neutral on a 120V or 277V circuit or to the other line on a 208V or 240V circuit.
Curt
