A blown fuse cuts power to one circuit in your home — you can spot it by looking inside the fuse box and checking whether the wire inside the fuse is broken or the metal cap is darkened. The fuse will look visibly different from the working ones next to it. Once you identify the bad fuse, you replace it with a new one of the same amperage rating, which takes about two minutes.

Key Takeaways

  • A blown fuse has a broken wire visible inside the glass or ceramic body, or a blackened metal cap — compare it directly to a fuse you know is working.
  • Before you open the fuse box, turn off the main breaker switch at the top of the panel to protect yourself from electrical shock.
  • Write down the amperage number printed on the fuse before you remove it, because you must replace it with a fuse of exactly the same amperage.
  • If a fuse blows again within a few days of replacement, the circuit has a real problem — stop replacing it and call an electrician.

Locate Your Fuse Box and Turn Off the Main Breaker

Your fuse box is usually in the basement, garage, or utility closet — look for a metal panel about the size of a small cabinet mounted on a wall. Open the door. Inside you will see rows of cylindrical fuses screwed into sockets, or sometimes cartridge-style fuses that sit in clips. At the very top of the panel is a larger switch or lever labeled "Main" — this is your main breaker.

Before you touch anything inside the box, flip the main breaker to the OFF position. This cuts power to the entire panel and protects you from electrical shock while you work. The main breaker switch will move noticeably — you will feel resistance. Once it is off, the panel is safe to touch.

Identify Which Fuse Is Blown

Look at each fuse in the box. A working fuse has a clear or slightly amber-tinted glass or ceramic body with a visible wire running through the center. The wire should be intact and unbroken. A blown fuse will have one of two telltale signs: either the wire inside is visibly broken or melted, or the metal cap on top of the fuse is blackened or scorched.

If you are unsure, compare a suspect fuse directly to one next to it that you know is working. The difference will be obvious — the blown one will look damaged or discolored. If multiple fuses look blown, you have a larger electrical problem and should call an electrician rather than replacing them yourself.

Note the Amperage Before You Remove It

Before you unscrew the blown fuse, look at the number printed on the metal cap or the side of the fuse body. This is the amperage rating — common sizes are 15, 20, or 30 amps. Write this number down or take a photo. This is critical: you must replace the fuse with one of exactly the same amperage. Using a higher amperage fuse is a fire hazard because it will not shut off the circuit if there is an overload.

Do not guess or assume all fuses in your box are the same size. They are not. Each circuit has its own rating based on the wiring and devices it serves.

Remove the Blown Fuse and Install the Replacement

Grip the blown fuse by its body (not the metal cap) and turn it counterclockwise, as if you were unscrewing a lightbulb. It will come free after a quarter turn or so. Set it aside. Do not touch the metal contacts inside the socket.

Take your replacement fuse — which you have already purchased to match the amperage of the one you removed — and insert it into the empty socket. Turn it clockwise until it is snug. Do not overtighten; you are looking for a firm fit, not maximum force. The fuse should sit flush with the others in the panel.

Restore Power and Test the Circuit

Once the new fuse is installed, flip the main breaker back to the ON position. You will hear or feel a click. The circuit is now live again. Go to the room or area that lost power and test a light switch or outlet to confirm power has returned.

If the lights come on and devices work normally, the job is done. If the fuse blows again within a few days, do not keep replacing it — this means something on that circuit is drawing too much current or there is a short. Repeated blown fuses are a sign of a real electrical fault that needs professional diagnosis.

When to Call an Electrician Instead

Do not attempt to replace a fuse if the fuse box itself is wet, corroded, or shows signs of burning or melting. Do not replace a fuse if you cannot safely reach the main breaker or if you feel any shock or tingling near the panel. These are signs of serious electrical problems.

Also call an electrician if a fuse blows repeatedly, if you cannot identify which fuse is blown because multiple ones look damaged, or if you are not confident reading the amperage rating. An electrician can diagnose why the circuit is overloading and fix the underlying cause rather than just replacing fuses over and over.

Frequently Asked Questions

Can I replace a fuse with a higher amperage one to stop it from blowing?

No. A fuse is designed to shut off the circuit when the current exceeds its rating — that is its job. Using a higher amperage fuse defeats that protection and creates a fire risk. Always match the amperage exactly.

What does it mean if a fuse blows right after I replace it?

It means the circuit has a real problem — either something plugged into it is drawing too much power, or there is a short in the wiring. Unplug devices from that circuit one at a time and see if the fuse stays intact. If it blows even with nothing plugged in, call an electrician.

Is it safe to replace a fuse myself?

Yes, as long as you turn off the main breaker first. The main breaker cuts power to the entire panel, making it safe to handle fuses. If you feel uncomfortable working inside the panel or if the box looks damaged, call an electrician instead.

How do I know if my home has fuses or circuit breakers?

Open your electrical panel. If you see cylindrical fuses screwed into sockets, you have a fuse box. If you see rows of switches that flip up and down, you have circuit breakers. Fuses are older but still common in many homes.