Can a breaker lose power without tripping?

Yes, an individual circuit breaker can experience a loss of power or fail to deliver voltage to its downstream branch circuit without the toggle handle physically moving to the tripped position. This can occur if the main service panel loses one of its incoming 120-volt utility feed legs, causing half of the bus bars and associated breakers to become completely de-energized even though their toggles remain in the "On" position. Additionally, internal mechanical failures or burned contact points inside the breaker can sever electrical continuity internally. You can troubleshoot electrical continuity safely by testing terminal output voltage with a digital multimeter while maintaining caution. You can verify that your corrective action is successful when having a licensed professional electrician inspect panel bus bars, verify incoming utility legs, or replace a defective breaker restores proper power delivery.