Why does my circuit breaker keep tripping?

If your circuit breaker keeps tripping every time the microwave hums, the hair dryer roars, or a space heater kicks on, your electrical panel is telling you something important. A breaker that shuts off power isn’t malfunctioning — it’s doing its job of protecting your home from an overload, a short circuit, or a ground fault. The question is which of those is happening in your Toronto-area home, and what to do about it before a nuisance turns into a fire hazard.

Introduction

This guide is for homeowners and tenants who keep resetting the same breaker and want to understand what’s really going on inside their panel. We’ll walk through the three main reasons breakers trip, how to tell them apart, what you can safely investigate yourself, and when it’s time to call a licensed electrician. Every home in Ontario is required to meet the standards of the Canadian Electrical Code (CEC), and the panel is one of the areas the Electrical Safety Authority (ESA) inspects closely — so working with a licensed pro isn’t just recommended, it’s the rule for anything more than a simple reset.

The three real reasons a circuit breaker keeps tripping

Modern breakers respond to three specific problems. Learning to spot the difference is the first step to fixing it.

• Overloaded circuit. Too many devices pulling current on a single 15- or 20-amp circuit. Typical culprit: a bedroom outlet running a space heater, a hair dryer, and a phone charger at once.
• Short circuit. A hot wire touches a neutral wire or another hot wire, creating a huge, sudden current spike. You may see scorch marks, smell burnt plastic, or hear a sharp pop.
• Ground fault. A hot wire touches a grounded metal box, plumbing pipe, or damp surface. Common in bathrooms, kitchens, garages, and outdoor outlets — which is exactly why those locations require GFCI protection.

How to figure out which one is happening

Start with observation, not tools. Which breaker trips? Does it trip immediately, or only when a specific appliance turns on? Does the tripped breaker feel warm? Answering those three questions narrows the diagnosis quickly.

1. Note the timing. If the breaker trips only when you plug in a heater, iron, or vacuum, an overload is the likely cause. If it trips the instant you reset it — with nothing plugged in — you probably have a short circuit or ground fault.
2. Unplug everything on the affected circuit, then reset the breaker once. If it holds, add loads one at a time until it trips. That’s your overload culprit.
3. Check for visible damage. Look for cracked outlets, chewed cables (mice love wiring insulation), scorch marks, or a burnt smell around switches and receptacles.
4. Try a different outlet for the same appliance. If a hair dryer trips one outlet but not another, the outlet or the wiring behind it is likely the problem — not the dryer.

When the breaker itself is the problem

Breakers are mechanical devices with thermal and magnetic elements inside. After 25 to 40 years, or after repeated tripping and resetting, the internal components weaken and the breaker starts tripping at loads well below its rating. Signs of a failing breaker include a lever that feels loose or spongy, a body that is hot to the touch even under a normal load, or a breaker that won’t stay in the “on” position at all. Replacing a breaker sounds simple, but it involves working inside an energized panel — that’s a job for a licensed electrician, not a weekend project.

AFCI, GFCI, and dual-function breakers: modern tripping causes

The Canadian Electrical Code now requires arc-fault circuit interrupter (AFCI) protection on most residential circuits and ground-fault (GFCI) protection in wet locations. These smart breakers detect problems the old thermal-magnetic breakers never could — a shorted lamp cord, a wire arcing behind a wall, moisture in an outdoor receptacle. That’s a good thing, but it also means new panels sometimes trip for reasons that would have been invisible in an older home. If a newly installed AFCI breaker trips repeatedly, don’t assume it’s defective. The first time in decades, it may finally be catching a genuine wiring flaw that has been quietly heating up your walls.

What you should never do

• Do not replace a 15-amp breaker with a 20-amp breaker to stop tripping. The wire in the wall is sized for the smaller breaker; a bigger breaker will let the wire overheat before it trips.
• Do not tape or wedge a breaker in the “on” position. This defeats every safety feature in your panel.
• Do not keep resetting a breaker that trips instantly. Each reset stresses the breaker and the wiring on the other side of it.
• Do not open the panel cover unless you are a licensed electrician. The bus bars behind the breakers stay energized even when the main is off.

Key takeaways

• A tripping breaker is a warning, not a nuisance — treat it that way.
• Overloads, short circuits, and ground faults are the three root causes; narrow it down before you call anyone.
• AFCI and GFCI breakers catch flaws older panels missed, so new-panel tripping is often a real find.
• Never upsize a breaker to solve tripping; the wire behind the wall determines the rating.
• Repeat tripping on the same circuit means it’s time to bring in a licensed electrician.

Frequently asked questions

Is it dangerous to reset a tripped breaker?

Resetting once is fine — that’s what breakers are designed to allow. Resetting the same breaker over and over within minutes is not fine. Each reset dumps current into whatever caused the fault, and if that’s a short circuit inside a wall, the heat builds up quickly. If a breaker trips a second time immediately after reset, stop and investigate.

Why does my breaker only trip in the summer?

Air conditioners, dehumidifiers, and portable fans add significant load to bedroom and living-room circuits that also feed lamps and TVs. Warm ambient temperatures also lower the trip threshold on thermal breakers slightly. If your panel is in a hot garage or attic, add another few degrees of derating.

Can a bad appliance keep tripping a breaker?

Yes. A microwave with a shorted magnetron, a fridge with a failing compressor, a lamp with a frayed cord — any of these can pull excessive current or leak to ground and trip a breaker. Isolate the appliance by testing it on a known-good circuit; if the new circuit also trips, the appliance is the source.

What’s the difference between an AFCI and a GFCI?

An AFCI (arc-fault circuit interrupter) senses the electrical signature of arcing — think a lamp cord being crushed by a chair leg — and trips to prevent a fire. A GFCI (ground-fault circuit interrupter) senses current leaking out of the circuit to ground, which is how people get electrocuted. Both are important; both are required by the CEC in specific locations.

How much does it cost to replace a circuit breaker in Toronto?

Replacing a single breaker typically runs between $150 and $350 including parts and labour, depending on breaker type — a standard breaker is inexpensive, while a dual-function AFCI/GFCI unit costs considerably more. Diagnosis is often billed separately, so ask for a written quote before work begins.

Do I need a permit to replace a breaker?

In Ontario, most panel and breaker work requires an ESA notification filed by a licensed electrical contractor. Replacing an entire panel definitely requires it; single breaker swaps sometimes fall under general service work but still must be performed by a licensed electrician. When in doubt, ask before the work starts.

Should I upgrade my whole panel if breakers keep tripping?

Not automatically. A panel upgrade makes sense if the existing panel is a known-recalled brand (Federal Pioneer Stab-Lok is the classic example), if it lacks capacity for modern loads like an EV charger or heat pump, or if it’s over 40 years old. If only one circuit trips and the rest of the panel is fine, targeted repairs are usually enough.

Contact us

Have a breaker that keeps tripping and you’re not sure why? Call EZSMART Electrical at 416-838-9006 or visit our contact page — we’ll diagnose the circuit, identify the fault, and get your power back to normal safely.