Circuit Breaker Keeps Tripping: What to Check First

A circuit breaker keeps tripping for one of three reasons, and all three mean the breaker is working. Either the circuit carries more current than its wire can shed as heat, or two conductors are touching, or current is escaping to ground. The most useful correction is this: a breaker that trips repeatedly is almost never a defective breaker, and swapping it for a larger one is the response that turns an annoyance into a fire risk. The wire in the wall sets the limit. The breaker only enforces it.

This post covers how to read the timing of a trip, how to isolate the circuit with nothing but a plug and a notepad, what an arc fault breaker and a ground fault breaker each react to, and the symptoms that mean you stop. Every number comes from a named primary source: the US Fire Administration, CPSC, OSHA, county building departments quoting the National Electrical Code, and technical data from Eaton and Schneider Electric.

Key takeaways

The breaker protects the wire, not the appliance: NEC 240.4(D) limits 14 AWG copper to 15 amperes, 12 AWG to 20 amperes and 10 AWG to 30 amperes.
A load running three hours or more counts as continuous and should sit at 80 percent of the breaker rating: 1,440 watts on a 15 ampere circuit, 1,920 watts on a 20 ampere one.
A standard 15 or 20 ampere breaker only trips instantly between 140 and 225 amperes, which is why arcing faults slip past it and need an AFCI.
A GFCI device reacts to an imbalance as small as 0.006 amperes, so a GFCI trip is evidence of leakage rather than evidence of load.
The US Fire Administration counted about 24,000 residential building electrical fires a year across 2014 to 2016, with 310 deaths and 871 million dollars in property loss.

What a tripping breaker is actually telling you

A thermal magnetic breaker has two sensing elements, and knowing which one operated tells you most of what you need. The thermal element is a bimetal strip that bends as it heats, so it responds slowly to a current that is moderately too high. The magnetic element responds to a sudden surge in milliseconds. Sustained overload bends the strip. A dead short yanks the magnetic trip. The delay you observe is the diagnostic.

CPSC describes the job plainly. Breakers must hold the current for which they are rated and open within specified time limits if overloading pushes current above that rating. The same guidance tells consumers what to do about it: do not simply replace the fuse or reset the breaker. A trip is a reading from an instrument, and resetting it without changing anything discards the reading.

The failure this protection prevents is not dramatic. It is heat inside a wall. The US Fire Administration found that wire and cable insulation was the item first ignited in 31 percent of residential electrical fires, framing in another 18 percent.

Overload: the slow trip that follows a pattern

Overload is the most common cause and the easiest to confirm, because it is reproducible. The breaker holds for seconds or minutes, then trips, and it trips when the same combination of things is running. Turn one off and the circuit survives. A space heater plus a hair dryer, a microwave plus a kettle: the pattern is additive, and it is about heat-producing appliances more than about how many items are plugged in.

The arithmetic is simple. A 15 ampere circuit at 120 volts carries 1,800 watts and a 20 ampere circuit carries 2,400 watts. Those are ceilings, not working figures. Schneider Electric’s technical guidance explains that a standard rated breaker is intended for continuous application at no more than 80 percent of its rating, where continuous means three hours or more, with shorter periods up to 100 percent allowed. Apply 80 percent and the practical limits become 1,440 and 1,920 watts.

Check the nameplate on each appliance rather than guessing. A 1,500 watt space heater alone exceeds the continuous allowance of a 15 ampere circuit. Add a 900 watt microwave and the circuit sits at 2,400 watts, above even the absolute rating. ESFI’s guidance is to plug only one heat-producing appliance into a receptacle outlet at a time, and to plug major appliances directly into a wall receptacle rather than an extension cord.

Motors complicate the reading. A compressor or pump draws several times its running current for a fraction of a second at startup, which the thermal element is designed to ride through. If a breaker trips the instant a refrigerator or air handler starts and holds fine otherwise, the motor is worth investigating before the circuit is. A heating system that trips on every call for heat belongs with a furnace that will not turn on: both point at the appliance, not the wiring.

Short circuit and ground fault: the instant trip

A short circuit is a direct connection between hot and neutral, bypassing the load. Current is then limited only by the resistance of the wiring, so it rises to hundreds or thousands of amperes and the magnetic element trips instantly. There is no holding period. The breaker goes the moment the circuit is energised, or the moment a damaged cord is flexed.

A ground fault is current leaving the intended path and returning through the grounding conductor, a metal enclosure, plumbing, or a person. CPSC’s fact sheet calls it an unintentional electrical path between a power source and a grounded surface, and notes that a GFCI responds to a difference between outgoing and returning current as small as 0.006 amperes.

Those two numbers, 0.006 amperes and several hundred amperes, are why a plain breaker cannot do everything. CPSC’s technical paper on arc fault circuit interrupters, by Lee, Trotta and King, reports that conventional thermal magnetic breakers on 15 and 20 ampere residential circuits have instantaneous trip levels between 140 and 225 amperes rms. A series arc at a loose terminal is limited by the load downstream of it, so it may sit at a few amperes while producing an arc temperature of several thousand degrees Celsius. The breaker never sees a number worth reacting to.

This is where one firm rule comes from. Never hold a tripping breaker in the on position, and never tape or wedge a handle. Defeating the mechanism means fault current keeps flowing through whatever damaged conductor started it. The trip is the only thing between that cable and the framing beside it.

Match the trip pattern to the fault

Before touching anything, write down what happened and when. Timing, repeatability and breaker type narrow the cause to one or two candidates almost every time. Use the table as a first pass, then confirm with the sequence below.

What you observe	Most likely cause	First thing to check
Holds for minutes, trips when several things run	Overload	Total wattage against 1,440 or 1,920 watts
Trips instantly every time you reset it, nothing plugged in	Short circuit in the fixed wiring	Stop and call an electrician
Trips instantly only when one cord is plugged in or moved	Short circuit or ground fault in that appliance	Remove the appliance from service
Trips only in damp weather or when an outdoor item is used	Ground fault	Moisture in an outdoor box, cord or fixture
Trips at the instant a motor starts, otherwise fine	Motor starting current or a failing motor	The appliance, not the circuit
Trips at random with no load change, on an AFCI breaker	Series arcing at a loose connection	Read the breaker’s trip code, then call an electrician

One caution on the second row. If a breaker refuses to hold with every device unplugged and every switch off, the fault is in the permanent wiring, a device box or the breaker itself, and self-diagnosis ends there.

Isolate the circuit by unplugging, step by step

Isolation is a subtraction exercise. Remove load until the breaker holds, then add it back one item at a time. It costs nothing, needs no tools beyond a flashlight, and gives an answer specific enough to act on.

Map the circuit. With the breaker off, note every outlet, light and appliance that has lost power, since circuits rarely follow room boundaries. Label the breaker.
Unplug everything on that circuit and turn off every switch it feeds, including ceiling fixtures and bathroom fans.
Reset the breaker. Push the handle fully to off first, since a tripped handle often rests between positions, then firmly to on.
If it trips again with nothing connected, stop. Leave the breaker off and call a licensed electrician.
If it holds, add loads back one at a time, waiting a few minutes after each. Give any motor-driven appliance several start cycles before calling it clear.
When it trips, you have your candidate. Leave that item unplugged, reset, and confirm the circuit is stable without it. Inspect its cord and plug for cracked insulation, crushed spots or heat discolouration.
If the circuit only fails with two or more items running together, and each is fine alone, that is an overload. Redistribute the load instead of resetting your way through the day.

Record the result. A dated note of which breaker, which devices and which outcome is what an electrician needs. CPSC also recommends exercising each breaker off and on three times a year so the mechanism does not stick.

Why a bigger breaker is the dangerous fix

The most common bad repair is fitting a 20 ampere breaker where a 15 ampere one kept tripping. It works in the sense that the tripping stops, and it works by removing the protection. OSHA states the principle in one line: conductors and equipment shall be protected from overcurrent in accordance with their ability to safely conduct current. The ability belongs to the conductor.

The National Electrical Code fixes the pairing for the small conductors used in homes. Jefferson County’s wiring guide for the 2026 code and the City of Boise’s homeowner permit guide both reproduce the NEC 240.4(D) limits in the same terms.

Copper conductor	Maximum overcurrent device	Typical residential use
14 AWG	15 amperes	General lighting and receptacle circuits
12 AWG	20 amperes	Kitchen small appliance and laundry circuits
10 AWG	30 amperes	Water heater, dryer and larger dedicated loads
Aluminium branch wiring	Electrician’s assessment required	Homes wired 1965 to the mid 1970s

Put a 20 ampere breaker on 14 AWG and the wire can be asked to carry a third more current than it is rated for, indefinitely, with nothing intervening. The heat has nowhere to go inside a stud bay. That is the mechanism behind the pattern the US Fire Administration documented: electrical arcing accounted for 74 percent of the heat source category covering 88 percent of residential electrical fires, with wiring the leading equipment involved at 31 percent.

The same logic rules out oversized fuses. CPSC’s home electrical safety checklist warns that the wrong size fuse can allow too much current to flow and cause the wiring to overheat, creating a fire hazard, and advises having an electrician identify and label the correct size. A panel with mismatched overcurrent devices can also surface during an inspection, worth knowing if you are working through lowering your home insurance costs.

This post quotes no replacement cost range, because no dated primary source was available for one. Price depends on breaker type, since an arc fault or dual function breaker costs several times a standard one.

What an AFCI trip and a GFCI trip each mean

Modern panels contain breakers that trip for reasons a thermal magnetic breaker cannot detect, and confusing the two leads people to chase load when the problem is a connection. An AFCI looks for the signature of arcing. A GFCI looks for current that does not come back. A dual function breaker does both. If the breaker has a test button, read its trips differently from the start.

Eaton’s technical data for its arc fault and dual function breakers publishes a diagnostic LED code for each cause: one blink for a series arc, a low current arc within a current pathway, two for a parallel arc between conductors, three for the electronic short delay backup, four for overvoltage at 160 volts rms or greater, five for a ground fault, six for a self test failure. No code is recorded for a plain thermal overload, a mechanical short circuit trip, a test button press or a manual switch-off, so a blank LED after a trip points back at ordinary overload.

Schneider Electric publishes a comparable routine for its QO and Homeline arc fault and dual function breakers, covering how to clear a latched LED indication and what to conclude if it will not clear. If the indicator pulses seven times after the reset sequence, the instruction is to contact a certified electrician to replace the breaker. That is the narrow case where the breaker itself is the faulty part, identified by its own diagnostics rather than by assumption.

Where these breakers are required is set by code, not preference. Jefferson County’s guide lists AFCI protection under NEC 210.12(B) for dwelling unit kitchens, bedrooms, living and family rooms, dining rooms, dens, sunrooms, closets, hallways and laundry areas, and GFCI protection under NEC 210.8 for bathroom, kitchen countertop, outdoor, garage, basement and crawl space receptacles, anything within six feet of a sink, and under 210.8(D) for dishwashers, ranges, dryers and microwaves. Replacing an AFCI with a standard breaker to stop the tripping is a code violation as well as a bad idea.

Both types have a test button, and CPSC recommends testing ground fault and arc fault interrupters monthly. A device that will not trip on its test button has failed and needs replacing.

When to stop and call a professional

Some findings end the do-it-yourself portion immediately. Stop and call a licensed electrician if you smell burning plastic near an outlet, switch or the panel; if the panel cover, a breaker or a receptacle is warm to the touch; if you see scorching or melted plastic; if you hear buzzing, sizzling or crackling from a receptacle or the panel; or if anyone gets a shock or tingle from an appliance, switch or faucet. ESFI lists flickering lights, warm or discoloured wall plates and a burning odour from switches among the signs of a circuit under stress, and none should be cleared by resetting a breaker.

The panel interior is not homeowner territory. The main lugs and service conductors stay energised with the main breaker off, and nothing inside is safe to probe without training and the right equipment. Do not remove the cover, tighten anything inside it, or attempt a breaker swap.

Aluminium branch circuit wiring deserves its own line. CPSC’s guidance covers cable installed between 1965 and the mid 1970s, and reports that homes built before 1972 with aluminium wiring are 55 times more likely to have a connection at an outlet reach what CPSC calls fire hazard conditions. The repairs it accepts are full replacement with copper cable, COPALUM crimp repair, which only manufacturer-trained electricians may install, or AlumiConn setscrew connectors fitted by a qualified electrician.

One more item travels with electrical trouble. If a trip has knocked out a furnace and you are running a portable heater meanwhile, check your alarms, since carbon monoxide detector placement decides whether one sounds early enough to matter.

Frequently asked questions

Can a circuit breaker go bad on its own?

Yes, but it is uncommon and it belongs last in the diagnostic order, not first. Isolate the circuit, rule out overload, rule out a faulty cord or appliance, and only then suspect the device. On an electronic breaker the manufacturer gives you a test: Schneider Electric’s instruction is that an indicator pulsing seven times after the reset sequence means the breaker should be replaced by a certified electrician.

How many times can you safely reset a tripped breaker?

There is no published number, and the question is the wrong one. CPSC’s instruction is not to simply replace the fuse or reset the breaker, because a trip warns that something on the circuit needs attention. Reset once after removing load. If it trips again with nothing changed, the next step is diagnosis, not another reset.

Why does the breaker trip with nothing plugged in?

That pattern points at the permanent wiring rather than anything you can unplug. A nail through a cable, a damaged conductor in a device box, a failed fixture, a loose neutral or moisture in an outdoor box can all produce it. Leave the breaker off and have an electrician trace it.

Is it safe to replace a 15 ampere breaker with a 20 ampere one?

No. NEC 240.4(D), as reproduced in county and city permit guides, limits 14 AWG copper to 15 amperes and 12 AWG to 20 amperes, and OSHA requires conductors to be protected in accordance with their ability to safely conduct current. A larger breaker leaves the wire unprotected. Adding a new correctly sized circuit is the legitimate fix.

What is the difference between an AFCI trip and a GFCI trip?

A GFCI reacts to current leaving the circuit, and CPSC puts its threshold at a difference as small as 0.006 amperes, making it a shock protection device. An AFCI reacts to the signature of arcing, which a standard breaker cannot see because its instantaneous trip sits between 140 and 225 amperes while a series arc may pass a few amperes. A GFCI trip suggests leakage. An AFCI trip suggests a damaged cord or loose connection.

Treat the trip as data. Note the breaker, the time, what was running and how long it held, then subtract loads until the circuit stays up. Most cases resolve to one heater on the wrong circuit or one cord that should have been retired. The cases that do not, the instant trips with nothing connected, the warm panels, the burning smells, are the ones worth an electrician’s visit.

Why Your Circuit Breaker Keeps Tripping and What to Check