Definition Of Shunt Trip Circuit Breaker

Shunt trip circuit breakers shut off electrical power during emergencies to prevent injury to people and damage to equipment. The shunt trip–a safety feature added to a regular circuit breaker–allows a location or appliance outside of the main breaker to also trigger a power shut-off.

The electrical current in a building passes through the system's circuit breaker unchanged if the current remains below a specified limit. If the current surges too high, the excess power charges an electromagnet in the circuit breaker, which throws a switch, cutting off power. Through a shunt trip, the electrical signal to charge this magnet can also come from a secondary source, such as a smoke detector or a manual switch.

Shunt trips either provide a remote manual shut-off switch or link directly to an appliance outside of the main breaker. A manual switch provides a human control. In cases of fire or storm damage, a person can immediately cut off power to a separate building. A smoke detector linked directly to a shunt trip allows the system to automatically shut itself down whether or not a person is aware of the danger.

Shunt trips prove useful in cases where water would come into contact with electricity. A shunt trip wired to a smoke dectector receives its shut-off signal at the same moment the smoke detector triggers the sprinklers. This not only minimizes the damage to electrical equipment, it also reduces the electrocution risk.