American Football NCAA Rule 3-3-2-e
e. Starts on the Referee’s Signal.
For each of the following reasons, the game clock is stopped on an official’s signal. If the next play begins with a snap, the game clock will start on the referee’s signal:
1. Team A is awarded a first down, either through play or by penalty with less than two minutes remaining in the 2nd quarter or the 4th quarter.
2. A Team A forward fumble goes out of bounds.
3. Other than with fewer than two minutes remaining in a half, a Team A ball carrier, fumble or backward pass is ruled out of bounds.
4. To complete a penalty (Exception: Rule 3-4-4-c).
5. An injury timeout is allowed for one or more players or an official (A.R. 3-3-5-I-V).
6. An inadvertent whistle is sounded.
7. A possible first-down measurement.
8. Both teams cause a delay in making the ball ready for play (A.R. 3-3- 1-III).
9. A live ball comes into possession of an official.
10. A head coach requests a conference or challenges an instant-replay decision.
11. The referee grants a media timeout.
12. The referee declares a discretionary timeout.
13. The referee declares a timeout for unfair noise (Rule 9-2-1-b-5 ).
14. An illegal pass is thrown to conserve time (A.R. 7-3-2-II-VII) (Exception: Rule 3-4-4-c).
15. The referee interrupts the 40/25-second count.
16. A player’s helmet comes completely off through play.
17. When either team commits a dead-ball foul.
18. Violation of a rule for mandatory equipment (Rule 1-4-4) or illegal equipment. (Rule 1-4-7)