Cal. Code Regs. tit. 8, § 3912 – Control of Operation.

(a) All amusement rides other than passenger operated or controlled rides shall be operated only by an authorized person. The operator shall be in the immediate vicinity of the operating controls during operation, even if automatic timing devices are used to control the time cycle of the ride, and no unauthorized person shall be permitted to handle operating controls during normal operation. All rides must have a stopping device within reach of the operator for use in case of an emergency.
(b) Each electrically driven ride shall have a disconnect switch within reach of the operator for use in case of an emergency.