A major penalty calls for the offending player to serve five minutes in the penalty box. The player that committed the penalty must go to the penalty box. His team will be short-handed, or down a skater, for five minutes. When one team is shorthanded the other team is on a power play. Once the penalty clock expires, the offending team will return to full-strength. If a goal is scored while a major penalty is being served, the power play will continue.
With a major penalty, the penalty clock will never be wiped, even if a goal is scored by the opposing team. This is not the case with minor penalties. The power play will end after a goal during a minor penalty.
Here is a list of major penalties in ice hockey with examples:
If a major penalty is called on a player and there are already two other players on his team serving penalties, the penalty clock will not start ticking until at least one of the other penalties has expired. However, a substitute can take his place on the ice. A team cannot have fewer than four players on the ice (one goalie and three skaters).
Sometimes calling penalties can be more complicated when multiple players on both teams are called for penalties at the same time.
In this case, the Referees will determine the on-ice strength of both teams by canceling out as many minor penalties, bench minor penalties, double-minor penalties, major penalties, and match penalties as possible.