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.

How It Works

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.