Federal 29 CFR 570.35(a), hours for minors 14 and 15 years of age (Fair Labor Standards Act child labor rules)
“(1) Outside of school hours;
(2) Not more than 40 hours in any 1 week when school is not in session;
(3) Not more than 18 hours in any 1 week when school is in session;
(4) Not more than 8 hours in any 1 day when school is not in session;
(5) Not more than 3 hours in any 1 day when school is in session, including Fridays;
(6) Between 7 a.m. and 7 p.m. in any 1 day, except during the summer (June 1 through Labor Day) when the evening hour will be 9 p.m.”
The same section defines a “week when school is in session” as any week the local public school district is in session and students must attend for at least one day or part of a day, and a “week” as the fixed workweek the employer sets.
Source: eCFR, 29 CFR 570.35