Why a breaker keeps tripping

A breaker that trips is not broken. It is doing its job: it cut the power because something on that circuit was wrong. The useful question is not how to keep it on, but why it went off. There are a few usual answers.

Overload: too much on one circuit

This is the most common cause. Every circuit is built to carry a certain amount of current. When the things plugged into it ask for more, the wire heats up and the breaker shuts the circuit off before the heat becomes a danger.

The clue is timing. An overload usually trips after a few minutes of heavy use, not the instant you switch something on. The usual suspects are appliances that make heat: space heaters, hair dryers, toasters, microwaves, kettles and portable air conditioners. Two of them on the same circuit is often enough.

Short circuit

A short circuit happens when a live wire touches a neutral or another live wire. The current jumps far above normal and the breaker trips at once, often with a pop. The cause can be a damaged cord, a failed appliance, a loose connection in an outlet or a screw driven through a cable inside a wall.

Ground fault

A ground fault is current escaping to a place it should not be: the metal body of an appliance, a damp surface or a person. It is common where there is water, such as bathrooms, kitchens, basements and outdoor outlets. Circuits there are usually protected by GFCI devices, which trip on very small leaks. My guide on GFCI and AFCI protection explains them.

Arc fault

Newer homes often have AFCI breakers, which listen for the electrical signature of sparking in damaged or loose wiring. They can trip because of a worn cord or a failing connection, and sometimes because of an appliance with a tired motor.

A breaker that has worn out

Breakers do fail with age, but it is the least likely cause, and it is the one people assume first. Treat the trip as real until someone has tested the circuit.

What you can safely check yourself

1. Notice what was running. Which room, which appliances, and whether the trip came at once or after a while.
2. Unplug everything on that circuit and turn off its lights.
3. Reset the breaker once. Push the handle firmly all the way to off, then back to on. A tripped breaker often rests in the middle and will not reset until it has been pushed fully off.
4. Bring things back one at a time. If the breaker holds until one particular appliance is plugged in, that appliance or its cord is the likely problem.
5. Spread the load. If it only trips when two heat-making appliances run together, move one of them to an outlet on a different circuit.
6. Look for a GFCI. If outlets are dead but no breaker has tripped, press the reset button on GFCI outlets in the bathroom, kitchen, garage, basement and outside. One of them often protects others further along.

Write down what you find. It saves time when I come to look.

When to stop and call an electrician

Stop resetting and leave the breaker off if:

• It trips again immediately with everything unplugged. The fault is in the wiring or in a device on the wall, not in an appliance.
• You smell burning, see scorch marks or feel heat at an outlet, a switch or the panel.
• You hear buzzing or crackling from the panel or from a wall.
• The breaker itself is hot to the touch or will not stay in the on position.
• Lights dim or flicker around the house when a large appliance starts.
• The same breaker trips again and again, even if it resets each time.

Two things should never be tried. Do not hold or tape a breaker in the on position. And do not swap it for a larger one: the breaker is sized to protect the wire, and a bigger breaker on the same wire lets that wire overheat inside your walls.

If you see smoke or flames, get everyone out of the house and call 911.

A circuit that keeps tripping from simple overload often needs one more circuit for the appliance that causes it. Tell me what you found and I will track down the rest. See troubleshooting and repair or ask for a free quote.