Eight hours of labor constitutes a day's work.  Any work in excess of eight hours in one workday and any work in excess of 40 hours in any one workweek and the first eight hours worked on the seventh day of work in any one workweek shall be compensated at the rate of no less than one and one-half times the regular rate of pay for an employee.  Any work in excess of 12 hours in one day shall be compensated at the rate of no less than twice the regular rate of pay for an employee.  In addition, any work in excess of eight hours on any seventh day of a workweek shall be compensated at the rate of no less than twice the regular rate of pay of an employee.

(Source: California Labor Code § 510(a))

Section 510 does not apply to an employee covered by a valid collective bargaining agreement if and only if the agreement expressly provides for the wages, hours of work, and working conditions of the employees, and if the agreement provides premium wage rates for all overtime hours worked and a regular hourly rate of pay for those employees of not less than 30 percent more than the state minimum wage.

(Source: California Labor Code § 514)

Meal Periods.
(A) No employer shall employ any person for a work period of more than five (5) hours without a meal period of not less than thirty (30) minutes, except that when a work period of not more than six (6) hours will complete the day's work the meal period may be waived by mutual consent of the employer and employee. Unless the employee is relieved of all duty during a thirty (30) minute meal period, the meal period shall be considered an "on duty" meal period and counted as time worked. An "on duty" meal period shall be permitted only when the nature of the work prevents an employee from being relieved of all duty and when by written agreement between the parties an on-the-job paid meal period is agreed to. The written agreement shall state that the employee may, in writing, revoke the agreement at any time.
(B) If an employer fails to provide an employee a meal period in accordance with the applicable provisions of this Order, the employer shall pay the employee one (1) hour of pay at the employee's regular rate of compensation for each work day that the meal period is not provided.

(Source: Cal. Code Regs. § 11010)

Rest Period.
(A) Every employer shall authorize and permit all employees to take rest periods, which insofar as practicable shall be in the middle of each work period. The authorized rest period time shall be based on the total hours worked daily at the rate of ten (10) minutes net rest time per four (4) hours or major fraction thereof. However, a rest period need not be authorized for employees whose total daily work time is less than three and one-half (3 ½) hours. Authorized rest period time shall be counted as hours worked for which there shall be no deduction from wages.
(B) If an employer fails to provide an employee a rest period in accordance with the applicable provisions of this Order, the employer shall pay the employee one (1) hour of pay at the employee's regular rate of compensation for each work day that the rest period is not provided.

(Source: Cal. Code Regs. § 11010)