How to Test a Square D Circuit Breaker

Circuit breakers are designed to ensure that an overload of electrical current on a circuit is stopped before damage can occur by shutting down, or tripping, the circuit when an overload occurs. However, if the circuit breaker trips often, it may be the circuit breaker rather than an overload or electrical device that is at fault. Test a Square D circuit breaker in a few steps to determine if the circuit breaker or another device is faulty.

Find the root cause when a circuit breaker trips frequently.

Unplug all electrical devices that are connected to the circuit of the Square D circuit breaker. Turn off any lights that also use the circuit in question.
Reset the circuit breaker. If the breaker stays in the "On" position, proceed to the next step.
Turn the circuit breaker off. Plug one electrical device back into the circuit and turn on the device. Turn on the circuit breaker. If the circuit breaker stays on, turn off the circuit breaker. Plug another device into the circuit and turn the devise on, then turn on the circuit breaker.

Repeat Step 3 until one of the electrical devices trips the circuit breaker. Unplug the suspect device and repeat Step 3 with a different device. If the circuit breaker trips, replace the circuit breaker. If the circuit breaker does not trip, test the device that tripped the breaker for a short circuit.