The answer to 'why is my circuit breaker dimming lights' is that a problem with the circuit breaker can cause the lights to dim. This is often a sign of an overloaded or faulty circuit breaker. The circuit breaker is designed to trip and cut power when it detects an electrical overload, which can cause the lights to dim temporarily before the breaker trips.
Some common causes include too many appliances or devices drawing power from the same circuit, a short circuit, or a problem with the circuit breaker itself. Symptoms may include flickering or dimming lights, frequently tripped breakers, or electrical devices not working properly.