What causes a circuit breaker to keep tripping and how do I find the problem?

Diagnosing a Circuit Breaker That Keeps Tripping

A breaker that trips once is doing its job. A breaker that trips repeatedly is telling you something is wrong — and the fix depends on which of several possible causes is responsible.

The Three Reasons Breakers Trip

1. Overload (most common)
The total current draw on the circuit exceeds the breaker's rating. A 15-amp breaker trips when more than 15 amps flows through it, and a 20-amp breaker trips above 20 amps.

Common overload scenarios in NB homes:

• Space heater (12.5A) + hair dryer (10A) on the same 15A circuit = 22.5A → trips


• Kitchen toaster (8A) + kettle (12A) on the same 20A circuit = 20A → right at the limit, may trip


• Multiple baseboard heaters on an undersized circuit during a cold snap


• Christmas lights added to an already loaded living room circuit

2. Short circuit
A hot wire touches a neutral wire or ground wire, creating a near-zero-resistance path that draws massive current instantly. The breaker trips immediately and forcefully — you may hear a loud snap or see a spark.

Causes:

• Damaged wire insulation (from a nail, screw, rodent, or age)


• Loose wire connection that lets conductors touch


• Faulty appliance with internal wiring failure


• Water intrusion into an outlet or junction box

3. Ground fault
Current leaks from the hot wire to ground through an unintended path — often through water, a person, or damaged insulation touching a metal surface. GFCI breakers and GFCI outlets detect this and trip at just 4–6 milliamps.

Common in NB:

• Outdoor outlets exposed to rain or snowmelt


• Basement outlets in damp or flooding-prone areas


• Bathroom circuits where humidity causes moisture in outlet boxes


• Well pump circuits with moisture in the conduit

Step-by-Step Diagnosis

Step 1: Identify the circuit
Your panel directory should tell you which rooms/outlets are on the tripped breaker. If your panel isn't labelled (common in older NB homes), now is a good time to map it — turn off one breaker at a time and note what loses power.

Step 2: Unplug everything on the circuit
Unplug every device, appliance, and lamp on the affected circuit. Turn off all switches.

Step 3: Reset the breaker
Push firmly to OFF, then to ON.

Step 4: Evaluate the result

If the breaker holds with nothing connected:

• The problem is one of the devices that was plugged in


• Plug devices back in one at a time, waiting 5 minutes between each


• When the breaker trips, the last device you plugged in is likely the culprit


• That device may have a short circuit, ground fault, or simply draws too much current for the remaining circuit capacity

If the breaker trips immediately with nothing connected:

• The problem is in the wiring itself — a short circuit or ground fault somewhere in the walls, outlets, or junction boxes on that circuit


• This requires a licensed electrician to diagnose. They'll use a megohmmeter (insulation resistance tester) to identify where the fault is located.

If the breaker trips after several minutes with nothing connected:

• Rare but possible — could be a failing breaker, a loose connection in the panel generating heat, or an intermittent wiring fault. Call an electrician.

When It's an Overload (Not a Fault)

If the breaker only trips when you're running specific combinations of appliances, the circuit is simply overloaded. Solutions:

Reduce the load — don't run the space heater and hair dryer at the same time

Move devices to different circuits — plug the space heater into an outlet on a different breaker

Add a new circuit — have an electrician run a dedicated circuit for the high-draw device. Cost: $300–$600 in most NB homes.

Specific to NB Homes

Electric baseboard heating circuits are the most common source of repeated tripping in New Brunswick. Each 240V baseboard heater draws 6–8 amps. If three or four heaters share a single 20-amp circuit, a cold snap that drives all of them to maximum output simultaneously can trip the breaker. The fix is splitting the heaters across multiple circuits — a TSANB-licensed electrician can assess and rewire the heating circuits for $500–$1,500 depending on scope.

Older panels with worn breakers — breakers lose their calibration over decades. A 20-amp breaker in a 40-year-old panel might trip at 17 or 18 amps due to aging thermal elements. Replacing the breaker ($50–$150 installed) solves this, but if the panel itself is old, consider a full panel upgrade.

When to Call an Electrician

• Breaker trips with nothing plugged in
• Breaker trips immediately upon reset (won't hold at all)
• You smell burning or see scorch marks
• Multiple breakers trip simultaneously
• The main breaker trips (whole house loses power)
• You've identified an overload but can't easily redistribute loads
• The problem started after a storm, flood, or renovation work

A diagnostic visit costs $80–$175 in most NB communities. If the electrician identifies a wiring fault, repair costs depend on location and accessibility — accessible junction box repairs run $100–$300, while a fault buried in a wall may require $500–$1,500 to locate and fix.

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