The short answer
Your breaker keeps tripping because something on that circuit keeps doing the thing the breaker was installed to stop. There are four candidates and they are easy to tell apart once you know what to watch. An OVERLOAD means the circuit is being asked for more current than it is rated to carry — the most common cause by a wide margin, and usually the least serious. A SHORT CIRCUIT means a hot conductor is touching a neutral one, which produces a large, immediate current and a breaker that trips the instant you reset it. A GROUND FAULT means current is escaping to ground somewhere it should not, which is what GFCI protection watches for and why those trip in bathrooms, kitchens and outdoors. An ARC FAULT is the signature of electricity jumping a gap — a loose connection, a damaged cord, a nail through a cable — and it is what AFCI breakers exist to catch, because a standard breaker cannot see it. The breaker itself can also simply be worn out, which is real but is the last thing to suspect rather than the first.
What none of those mean is that the breaker is faulty for tripping. That is worth saying plainly because the instinct to make the tripping stop is the instinct that causes the one genuinely dangerous outcome in this whole subject, which we come to below.
The four things that trip a breaker
OVERLOAD. Every circuit has an amperage rating, and every device on it draws some of that. Run a 1,500-watt space heater and a microwave on the same 15-amp kitchen circuit and you are asking for more than it has. The tell is timing: it trips when you add something, usually within a minute or two rather than instantly, and it holds fine once you move the load elsewhere. Worth knowing that a circuit's usable capacity is lower than its label suggests — anything running three hours or more counts as a continuous load and should stay under 80 percent of the rating, which puts a 15-amp circuit's practical ceiling at about 1,440 watts. A single space heater is already past it.
SHORT CIRCUIT. A hot conductor touching a neutral one produces an enormous current for a fraction of a second. The tell is that the breaker will not stay reset — it trips again immediately, often with a sound, and sometimes with a smell or a visible mark at whatever failed. A damaged extension cord, a cable pinched by a screw, or a failed appliance are all common. This one is not a nuisance and does not want repeated resetting.
GROUND FAULT. Current that finds a path to ground other than the one intended — through moisture, through a damaged cable, through a person. GFCI protection measures whether the current going out on the hot equals the current coming back on the neutral, and trips on a difference of 4 to 6 milliamps. That threshold was chosen around what a human heart can survive, not around what damages wiring, which is why GFCIs live where water and electricity meet. A GFCI that trips outdoors after heavy rain, or in a bathroom on a humid morning, is often working correctly rather than failing.
ARC FAULT. Electricity jumping a small gap — at a loose terminal screw, in a cable nicked during a long-ago remodel, inside a cord crushed under a chair leg. Arcing produces relatively little current, which is the problem: a standard breaker sees nothing worth acting on while the arc quietly makes heat. AFCI breakers watch the shape of the current for the signature of arcing instead of just its size. They are more sensitive than what most people grew up with, and they do sometimes react to motors and switching power supplies. California requires AFCI protection more broadly than the national code base does, so newer and remodelled homes here have more of them than homes elsewhere.
How to work out which one you have
Behaviour tells you most of it before anyone opens anything.
- Trips only when you switch something on, and holds once you unplug it — overload. Move the load to another circuit.
- Trips instantly on reset, every time, with nothing plugged in — short circuit or a hard ground fault. Stop resetting it.
- Trips only in wet weather, or only on outdoor and bathroom outlets — ground fault, and quite possibly correct behaviour.
- Trips at random with no pattern you can find, on a newer or remodelled part of the house — arc fault, or an AFCI reacting to a particular appliance.
- Trips only when one specific appliance runs, on any circuit — the appliance, not the house.
- Trips at loads it used to carry without complaint, and nothing else has changed — often the breaker or the panel itself. Common on older equipment, and worth having looked at rather than lived with.
One cause sits outside that list, because it is about the equipment rather than the circuit. A breaker trips on heat as well as on current, so anything making heat at the breaker itself will trip it early — a worn breaker whose contacts no longer close cleanly, or a tired connection where the breaker meets the panel bus. The circuit is fine and the load is one it used to carry; the breaker is simply running hot before the current gets anywhere near its rating. We see it often enough on older panels that it is worth checking before anyone starts hunting for a fault that is not there — and a connection making heat inside a panel is worth finding for its own sake.
One caveat on all of that: panel labelling is frequently wrong, and often decades old. If a breaker trips and nothing you expected to lose power actually did, the label is probably lying rather than the circuit behaving strangely. It can also mean two circuits share a neutral, so a fault on one surfaces on the other.
The one thing not to do
Do not fit a larger breaker to stop the tripping. This is the single most consequential mistake in this subject, and it is common enough that we find it on inspections regularly — nearly always installed years earlier by somebody trying to be helpful.
The reasoning that leads there is intuitive and wrong. A breaker does not protect the appliance, and it does not protect you from the appliance. It protects THE WIRE — it exists so that the conductor buried in your wall never carries more current than it can shed as heat. NEC 240.4(D) caps 14-gauge wire at 15 amps and 12-gauge at 20 amps, and California adopts those limits through the CEC. Put a 20-amp breaker on a 14-gauge circuit and the wire can now legally-speaking carry a third more current than it is rated for, continuously, with nothing left in the system that will ever object. The heat goes into a wall cavity where no one can see it, and the failure, when it comes, comes without warning.
If a circuit genuinely needs more capacity, the answer is a circuit built for it — heavier conductor, correct breaker, and where relevant a dedicated circuit for the appliance that keeps demanding it. That is a real fix. A bigger breaker is not a smaller version of that fix; it is the opposite of it.
When it stops being a diagnostic question
Most tripping is a puzzle rather than an emergency. These are the signs that change that, and any one of them is enough:
- A burning smell, or a smell like hot plastic, anywhere near the panel, an outlet or a switch
- Scorch marks, browning, or melted plastic on an outlet, a switch plate or the panel
- Warmth you can feel through the panel cover, or a breaker that is hot to the touch
- Buzzing, crackling or sizzling from the panel or a device
- A breaker that will not reset at all, or that trips again instantly every time
- Anyone in the house has felt a shock or a tingle from an appliance, a tap or a switch
In any of those cases, stop using the circuit, leave the breaker off, and call us. Do not keep resetting it, and do not open the panel to look — the panel cover is the only thing between you and conductors that are still live even with every breaker off. If you can smell burning right now, or see smoke or sparking, call 911 first.
What an older panel changes
An old panel does not make a circuit trip more often, but it does change what tripping tells you. In a Federal Pacific or a Zinsco panel the documented concern runs in the opposite direction: those brands have a failure mode where breakers do NOT trip when they should, staying closed while the wire downstream heats up. If yours is one of those, a breaker that trips is at least still doing its job, and the ones to worry about are the ones that never do. Both have their own guides below.
The other thing age changes is capacity. A house wired for the loads of 1965 is now running induction hobs, heat pumps, EV chargers and a home office. Circuits that trip under modern use are not always faulty — sometimes they are simply being asked for something the house was never built to deliver, and the honest answer is more capacity rather than more troubleshooting.