You can’t actually “reset” a fuse the way you flip a circuit breaker back on. Fuses are one-time-use devices. When one blows, a metal strip inside melts to cut power to that circuit, and the fuse needs to be replaced with a new one of the same amperage rating. The good news: swapping a blown fuse takes about two minutes once you know what you’re doing.
How to Tell Which Fuse Blew
Open your fuse box and look at each fuse. Most older homes use round, screw-in plug fuses with a small glass window on the face. A blown fuse usually shows one of two telltale signs through that window: a broken or melted metal strip (meaning the circuit was simply overloaded) or a blackened, discolored window (meaning a short circuit caused a more dramatic failure). Either way, that fuse is dead and needs replacing.
If you’ve lost power to part of your home but aren’t sure it’s a fuse, check whether other areas still have electricity. A blown fuse kills power to one circuit while everything else on the panel keeps working normally. If your entire house is dark, the problem is more likely your utility supply or the main switch at the top of the fuse box, not a single blown fuse.
Before You Touch Anything
Stand on a dry surface. If the floor near your fuse box is damp, lay down a dry rubber mat or a thick, dry board. Water and electricity are a dangerous combination, and older basements where fuse boxes tend to live are often damp. Keep one hand at your side or in your pocket while working inside the panel. This old electrician’s habit prevents current from traveling across your chest if something goes wrong.
Locate the main switch, which is typically a large switch or pull-out block at the top of the panel. This controls all electricity entering your home. For maximum safety, turn it off before removing or inserting any fuse. With the main switch off, the individual fuse sockets are de-energized and safe to handle.
Know Your Fuse Type
Older homes use one of two styles of screw-in fuses, and it matters which one you have.
- Edison base (plug fuses): These have a standard threaded base, similar to a light bulb. They screw into any standard fuse socket regardless of amperage, which is both their simplicity and their danger. Nothing physically prevents you from putting a 30-amp fuse where a 15-amp fuse belongs.
- Type S (rejection base) fuses: These have a smaller, specially shaped base that only fits an adapter matched to a specific amperage range. Once a Type S adapter is installed in a socket, you can only screw in a fuse of the correct rating. This is a safety upgrade designed to prevent overfusing.
Some older panels also use cartridge fuses, which are cylindrical tubes that slide or snap into spring clips rather than screwing in. These are typically found on higher-amperage circuits like your main disconnect, electric range, or dryer circuit. Replacing a cartridge fuse involves pulling it straight out of its clips (use a plastic fuse puller, not your fingers) and sliding in an identical replacement.
Replacing a Blown Plug Fuse
Turn off the main switch. Unscrew the blown fuse by turning it counterclockwise, just like removing a light bulb. It should come out easily. Look at the face or the metal rim of the old fuse for its amperage rating, usually 15, 20, or 30 amps. This number is critical.
Take a new fuse with the exact same amperage rating and screw it clockwise into the empty socket until it’s snug. Don’t overtighten. Turn the main switch back on, and power should return to that circuit.
If you don’t have a replacement fuse on hand, bring the blown one to a hardware store. Plug fuses are still widely available and cost about a dollar each. Buying a small box to keep near the panel saves you a trip next time.
Why Amperage Matching Is Not Optional
This is the single most important safety point with fuse boxes. A fuse protects the wiring inside your walls, not just the appliances plugged into them. A 15-amp circuit uses thinner wire that can safely carry 15 amps of current. If you screw in a 20- or 30-amp fuse because it “fits,” the fuse won’t blow when the wire is already overloaded. The wire overheats instead, and that heat happens inside your walls where you can’t see it.
If you find 25- or 30-amp fuses already installed in your panel, they are likely oversized for the circuits they protect. Most standard household lighting and outlet circuits are wired for 15 or 20 amps. Someone in the past probably got tired of blown fuses and “solved” the problem by installing bigger ones. This is a genuine fire hazard. Replace oversized fuses with the correct rating for the wire gauge on that circuit. If you’re unsure what the correct rating is, an electrician can check the wire size and label each circuit properly.
When a Fuse Keeps Blowing
A fuse that blows once after you’ve been running a space heater, hair dryer, and microwave on the same circuit just means you overloaded it. Spread those appliances across different circuits and the new fuse should hold fine.
A fuse that blows repeatedly, especially right after you replace it, signals a deeper problem. Common causes include outdated wiring that can no longer handle modern electrical loads, moisture getting into outlets or junction boxes, rodent damage to wire insulation, or a short circuit in an appliance or in the wiring itself. Don’t keep replacing the fuse hoping it sticks. The fuse is doing its job by blowing, and the real issue needs to be found and fixed.
Should You Upgrade to a Breaker Panel?
Fuse boxes are not inherently unsafe when properly maintained with correctly rated fuses, but they have practical limitations. Most are 60-amp panels, which was adequate when homes had a refrigerator, a few lights, and a radio. Modern households with central air, multiple computers, kitchen appliances, and EV chargers can easily exceed that capacity.
Insurance companies sometimes charge higher premiums or decline coverage for homes with fuse panels. If you sell the home, buyers and inspectors will flag it. Current electrical codes, based on the National Electrical Code (NEC) 2023 edition, require updated safety features when service equipment is replaced, including an emergency disconnect in a readily accessible outdoor location for one- and two-family homes. That means a panel upgrade isn’t just swapping the box; it involves bringing the entire service entrance up to modern standards.
If your fuses blow rarely and your electrical demands are modest, the panel can serve you fine for years with proper fuse sizing. If you’re frequently blowing fuses, adding new appliances, or planning a renovation, upgrading to a breaker panel is the more practical long-term solution. A typical upgrade runs between $1,500 and $3,000 depending on your area and the complexity of the work.