Why is one circuit breaker in my panel making a clicking or humming noise?

A circuit breaker that clicks or hums is potentially dangerous — it may be arcing internally, failing to make solid contact with the bus bar, or trying to trip under an overload condition. Any unusual noise from your electrical panel warrants prompt investigation by a licensed electrician. Do not ignore it, and do not attempt to inspect the inside of the panel yourself — the bus bars carry 240 volts at up to 200 amps, and contact is instantly lethal.

A humming or buzzing breaker is often caused by a breaker that is not fully seated on the bus bar. Circuit breakers clip onto the panel's bus bar with a friction connection, and over time — particularly in panels that experience vibration from nearby HVAC equipment, a clothes dryer on the same wall, or even regular traffic if the panel is near a heavily used door — a breaker can work slightly loose. The imperfect contact between the breaker and bus bar creates electrical resistance, which produces heat and an audible hum. This condition is dangerous because the heat can damage the bus bar itself, potentially compromising other breakers on the same bus.

An AFCI (arc fault circuit interrupter) breaker that clicks repeatedly may be detecting arcing on the circuit it protects. AFCI breakers are required on bedroom circuits in Ontario and contain sophisticated electronics that monitor for the electrical signature of dangerous arcs — frayed wires, loose connections, and damaged insulation. If an AFCI breaker clicks and trips frequently, it is likely detecting a real arc fault somewhere on the circuit. Common sources include loose connections at outlets or switches, a nail or screw that has pierced a wire inside the wall, or a damaged cord on a lamp or appliance. While some older AFCI breakers were prone to nuisance tripping, current-generation units are much more reliable, and repeated trips should be taken seriously.

A breaker may also hum under heavy load even when functioning normally, though this hum should be barely audible. A breaker feeding a circuit with inductive loads — motors for a refrigerator compressor, sump pump, or furnace blower — can produce a faint 60 Hz hum when the motor is running. This is normal if it is quiet and consistent. A hum that is loud enough to hear from across the room, changes in intensity, or is accompanied by a warm breaker is abnormal.

Warmth at the breaker is a critical warning sign. While you should never remove the panel cover, you can carefully touch the front of individual breakers with the back of your hand (if accessible) to check for unusual warmth. A breaker that is noticeably hot compared to its neighbours indicates high resistance at the connection, internal failure, or sustained overloading. If a breaker is hot to the touch, turn it off immediately and call a licensed electrician.

In many older GTA homes — particularly those with Federal Pioneer, Federal Pacific, or Zinsco panels — breaker issues can indicate systemic panel problems. Federal Pacific Stab-Lok breakers have a well-documented history of failing to trip during overloads and are considered a fire hazard by many electrical professionals. If you have one of these panels and notice any breaker making noise, panel replacement should be a high priority. A panel replacement in the GTA runs $2,000-$5,000 depending on the scope.

A licensed electrician will inspect the breaker, check its connection to the bus bar, measure the load on the circuit, and determine whether the breaker needs replacement or whether a deeper problem exists. A diagnostic service call in the GTA runs $150-$350. Toronto Electrical Repair can connect you with a licensed electrician through the Toronto Construction Network to assess the situation safely.