A blown fuse can’t actually be reset. Unlike circuit breakers, which flip back on with the push of a switch, fuses are one-time-use devices that physically melt when a circuit overloads. You need to replace the blown fuse with a new one of the same amperage. The good news: this is a straightforward job that takes about five minutes once you know what you’re looking at.
That said, many people use the word “fuse” when they actually have a circuit breaker panel, which is standard in any home built after the 1960s. If your electrical panel has rows of small rectangular switches, you have circuit breakers, and you can simply reset the tripped one. If your panel has glass or ceramic screw-in plugs (or cylindrical cartridges), you have actual fuses, and you’ll need to swap out the blown one.
How to Tell What You Have
Your home’s electrical panel is a metal box, usually in a basement, garage, utility room, or on an exterior wall. Open the door and look inside. Circuit breaker panels have labeled switches arranged in rows. Fuse boxes have round screw-in plugs (similar in size to a light bulb base) or rectangular pull-out blocks that hold cylindrical cartridge fuses. Most fuse boxes contain six to twelve fuses.
If you see switches, skip ahead to the circuit breaker section below. If you see plugs or cartridges, keep reading.
Replacing a Blown Screw-In Fuse
Screw-in fuses (also called plug fuses) are the most common type in residential fuse boxes. Each one protects a single circuit in your home. When it blows, the small metal strip inside melts, and you can usually see this through the glass window on the fuse’s face. A blown fuse will have a darkened or cloudy window, or you’ll see a broken strip of metal inside.
Here’s the process:
- Turn off the main power. Locate the main disconnect switch or main fuse at the top of your fuse box and switch it off. This cuts power to all the individual fuses and makes them safe to handle. Never remove a fuse with the main power on.
- Stand on a dry surface. If your fuse box is in a basement or garage, make sure you’re not standing in water or on a damp floor. Place a dry rubber mat or a thick piece of plywood under your feet if the floor is wet.
- Identify the blown fuse. Look through the glass face of each fuse. The blown one will be discolored, or you’ll see the broken filament inside. If fuses are labeled by room or circuit, that narrows it down quickly.
- Unscrew the blown fuse. Turn it counterclockwise (just like a light bulb) and pull it out.
- Match the amperage exactly. Check the number printed on the face of the old fuse. Common residential ratings are 15, 20, or 30 amps. Buy an identical replacement. Never install a fuse with a higher amperage rating than the one you removed. A higher-rated fuse won’t blow as easily, which sounds like a solution but actually lets the wiring overheat and creates a fire risk.
- Screw in the new fuse. Turn it clockwise until it’s snug. Don’t overtighten.
- Restore main power. Flip the main disconnect back on. The circuit should now be live again.
Keep a few spare fuses of each amperage stored near your fuse box. Hardware stores sell them for about a dollar each, and having them on hand means you’re not making a late-night store run when the lights go out.
Replacing a Cartridge Fuse
Cartridge fuses are cylindrical tubes found in pull-out fuse blocks. They typically protect larger appliances like electric dryers, ranges, or your home’s main power feed. You won’t be able to see whether a cartridge fuse is blown just by looking at it.
To remove one, pull the entire fuse block straight out of the panel. Then use a fuse puller, a plastic plier-like tool designed for this job, to grip the middle of the cartridge and pull it free from its metal clips. Don’t use your bare hands or metal pliers. If you have a multimeter, you can test the old fuse for continuity to confirm it’s blown before buying a replacement. Slide the new cartridge (same amperage, same physical size) into the clips and push the fuse block back into the panel.
Resetting a Tripped Circuit Breaker
If your home has a breaker panel instead of a fuse box, the fix is simpler. When a breaker trips, it moves to a middle position between ON and OFF, or it flips all the way to OFF. Some breakers have a small indicator window that turns red or orange when tripped.
To reset it, push the switch firmly to the full OFF position first, then flip it back to ON. This two-step motion is important because a tripped breaker sometimes won’t engage if you try to go straight to ON. If the breaker trips again immediately, leave it off. That usually means there’s a short circuit or a ground fault on that circuit, not just an overload.
Why Fuses Blow in the First Place
The most common cause is a simple overload: too many appliances drawing power from a single circuit. Hair dryers, vacuum cleaners, microwaves, and space heaters are frequent culprits because they pull a lot of current. A standard 15-amp household circuit on 120-volt wiring can handle about 1,800 watts total, and you should stay under 80 percent of that (roughly 1,440 watts) to avoid tripping the fuse. A single hair dryer can pull 1,500 watts on its own, so plugging one into a circuit that’s also running other devices will easily push it over the limit.
Short circuits are another cause. This is when a wire’s insulation breaks down or a connection comes loose, allowing current to take an unintended path with very little resistance. The surge of current blows the fuse instantly. Short circuits tend to produce a blackened or discolored fuse window, sometimes with a metallic smell. A ground fault is similar but involves current leaking to a grounded metal surface, like an appliance housing or a metal junction box.
If you can trace the blown fuse to a specific moment, like when you turned on a particular appliance, unplug that appliance before replacing the fuse. If the new fuse blows right away with nothing plugged in, the problem is in the wiring itself, not your devices.
Preventing Repeat Blowouts
A 20-amp, 120-volt circuit has a total capacity of 2,400 watts but should only carry about 1,920 watts under the 80 percent rule. Before plugging in a high-draw appliance, check the wattage label on the device (usually on the bottom or back) and add it to whatever else is already running on that circuit. If the total exceeds 80 percent of the circuit’s capacity, move something to a different outlet on a different circuit.
Spreading high-wattage appliances across multiple circuits is the single most effective way to stop blowing fuses. If your kitchen has only one circuit serving all the countertop outlets, running the microwave, toaster, and coffee maker at the same time will overload it every time. Stagger their use, or have an electrician add a dedicated circuit for the heaviest appliance.
When the Problem Is Bigger Than a Fuse
A fuse that blows once because you plugged in too many things is normal. A fuse that blows repeatedly on the same circuit, especially with nothing obvious overloading it, points to a wiring problem that replacing fuses won’t fix.
Call a licensed electrician if you notice any of these signs at your panel: a burning smell or scorch marks on or around the fuse box, rust or water stains inside the panel, buzzing or humming noises coming from the box, or fuses blowing in multiple circuits around the same time. These are signs of damaged wiring, moisture intrusion, or a panel that’s failing.
Homes built before 1960 often still run on original fuse boxes that don’t offer the arc fault or ground fault protections built into modern breaker panels. If your fuse box is from that era and you’re dealing with frequent blowouts, upgrading to a circuit breaker panel improves safety and can also affect your homeowner’s insurance eligibility, since some insurers charge higher premiums or decline coverage for homes with outdated fuse boxes.