R 408.12423 Electrical.

Rule 2423. All A.C. control circuits and solenoid valve coils shall be powered by not more than a nominal 120-volt A.C. supply obtained from a transformer with an isolated secondary. Higher voltages that may be necessary for operation of machine or control mechanisms shall be isolated from any control mechanism handled by the operator, but motor starters with integral start-stop buttons may utilize line voltage control. All D.C. control circuits shall be powered by not more than a nominal 240- volt D.C. supply isolated from any higher voltages.