Definition
A circuit breaker designed so that it will open the circuit when an overload occurs even if the operating handle is held in the closed position. The internal trip mechanism acts independently of the handle, so the breaker cannot be forced to stay closed during a fault.
Plain English
A circuit breaker that will pop open by itself if there's an electrical problem, even if you're holding the switch in the 'on' position. You can't override it by force.
Context Anchor
Seen in aircraft electrical system descriptions, maintenance information, and cockpit circuit breaker panels.
Derivation
Trip-free' literally means the tripping action is free of (independent from) the handle. The breaker is free to trip regardless of what the handle is doing.
Why Pilots Care
It prevents forcing power through a faulty circuit, reducing risk of fire, equipment damage, or in-flight electrical failure.
Analogy
It is like a spring-loaded safety latch that releases when the load is too high, even if someone keeps pushing on the handle.
Intuition Check
“Trip-free” does not mean the breaker will not trip. It means the breaker is free to trip open even if the pilot tries to hold it on.
Example Sentence 1
Most aircraft circuit breakers are trip-free, so holding one closed during a short circuit will not keep current flowing through the faulted wire.
Example Sentence 2
After clearing the overload, the pilot reset the trip-free circuit breaker and verified normal current flow.