The Occupational Health and Safety Administration (OSHA) does not limit the number of overtime hours an employee can work per day or per week. OSHA regulations strictly adhere to the labor laws outlined in the Fair Labor Standards Act (FLSA), which limits non-overtime hours to 40 per week for employees who come under its overtime provisions.
The U.S. Department of Labor enforces laws concerning workplace safety. Under the Department of Labor umbrella, OSHA and the Wage and Hour Division work together to ensure employee protection standards are met. OSHA is generally more focused on workplace hazards, and FLSA provides the guidelines for wages and hours.
While FLSA affects more than 130 million workers, there are a number of occupations exempt from its overtime and/or minimum wage provisions. For non-exempt employees, FLSA is enforced by the Wage and Hour Division, which ensures that employers pay at least the federal minimum wage and one-and-a-half times the regular pay rate after 40 hours. Weekends, holidays and other "regular days of rest" are not considered overtime under the act unless an employee has already worked 40 out of the previous 168 hours.
OSHA compensation regulations actually defer to the FLSA, which has no set limit to the number of hours an employee can work. OSHA's "maximum hours provision"---in which it refers to FLSA Section 7a---only applies to the maximum hours someone can work for non-overtime pay within a week. Because FLSA does not explicitly state that more than eight hours in a day would constitute overtime, OSHA does not limit the number of hours per day an employee can work.
Other Hours Worked
According to the Wage and Hour Division, any employee who remains on work premises while "on-call" must be compensated. Employees must be compensated for work even if they have requested to stay and finish a task. Employees required to be on duty for 24 hours or less must be compensated even if permitted to sleep. Employees required to be on duty more than 24 hours can negotiate sleeping periods. Rest periods of 20 minutes or less must be compensated. Some states have "minimum rest periods" and other overtime laws not outlined in OSHA regulations or the FLSA.
While OSHA and FLSA do not outline maximum hours per week, many employers understand the safety risk---and productivity loss---associated with long workweeks. A report on a yearly study on the "EHS Today" website outlines these risks. In 2004, the study found that the health care costs of "high-overtime" employees were five times the cost of their "low-overtime" counterparts. The study consistently shows that increased overtime results in stress and fatigue. It also finds that more overtime leads to more---and more severe and costly---workplace accidents.