How Do I Replace a Blown Fuse in My House?

Gemma Johnstone
Written by Gemma Johnstone
Updated August 13, 2021
Mom and daughter reading by flashlight
Choreograph via Getty Images

Don’t panic if your home power suddenly shuts off—it could just be that an electrical system fuse has blown

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In modern homes, if your power goes out when you’re running the dishwasher and washing machine and microwave, you need to locate the circuit breaker box and flip a tripped switch to restore power. But in older homes (typically those built in the mid-1960s or earlier), you might have a fuse box instead. When there’s a power surge, the fuse attached to that circuit will blow and need replacing before it’s possible to restore the power.

Although not as simple as resetting a tripped circuit breaker, replacing a blown fuse is still a relatively simple task. By following a few steps, you can do it without having to call out an electrician.

Difficulty: 2/5

Time: 15 minutes

Tools and Materials Needed:

  • Flashlight

  • Spare

  • Fuses

  • Optional safety glasses

  • Optional continuity tester

  • Fuse puller for cartridge fuses

1. Locate the Fuse Box

Living room with string lights
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Ideally, you should know where your fuse box is before your power flickers out. You typically find them in non-living spaces in your home, such as the basement, garage, hallway, utility room, or even the attic.

2. Establish Which Fuse Has Blown

When a circuit breaker trips, it’s easy to see because the switch will be in the OFF position. For a blown fuse, you have to examine each fuse in the electrical panel to identify which one is the problem. 

Usually, the fuse relates to a particular area of the home, but if the power in the entire house goes out, then one of the main fuses has likely blown. The main fuse block location is usually at the top of the box. The other circuit fuses will be underneath and typically have labels to show which part of the house they cover.

Take a flashlight so you can read these labels easily. Scorching is common on the glass section of the fuse, turning it opaque rather than clear. Sometimes, melting of the metal strip inside the fuse is possible too.

Depending on the type of fuses your electrical panel has, if it isn’t apparent which has blown, you could invest in a piece of equipment called a continuity tester. It makes things more time-consuming, though—you have to test each fuse, and if the tester doesn’t light up, this means it’s not working.

3. Turn Off Any Appliances and Lights Attached to the Fuse

Before replacing a fuse, make sure you turn off any lights and appliances attached to it. This is so you won’t risk overloading the electrical circuit again and cause the new fuse to blow immediately. Plus, you can then gradually turn things on again, which could help identify if a particular appliance is causing the circuit overload.

4. Change the Fuse That Has Blown

Before changing any fuses, always turn off the main power to the fuse box. This prevents any electrical current from running through the panel while you’re making the change.

You then need to remove the blown fuse and replace it with one that’s the same type and size. It’s a good idea to keep spare fuses to prevent a delay in restoring electricity.

Fuse Types

Below are the three most common types found in fuse boxes.

Cartridge fuses: These cylindrically shaped fuses have metal caps at both ends and a longer glass middle. You usually see these in 240-volt household circuits and they often use 60-amp main fuses and 30 or 40-amp circuit fuses. They fit into a fuse block that’s inserted into the box and removed by pulling a handle. After removing the block, you can replace the individual fuse. Using a fuse pulling tool makes it easier to remove the fuses from the block.

Edison-base fuses: Also called Type-T, these screw-in fuses have a light bulb-style base. You find these in household circuits that can handle 125-volts maximum. The maximum rating for these fuses is 30-amps.

Type-S: Also known as tamper-proof or rejection-base fuses, these two-part varieties have a screw-in fuse that attaches to an adapter that connects to an Edison base. The threading is unique for each fuse amperage, making it impossible to attach a fuse with incorrect amperage capacity.

Fuse Size

It’s essential that you replace any fuses with a like-for-like amperage capacity. Manufacturers print the ampere rating on the fuses for ease of reference. Installing a larger capacity fuse can overheat and damage the circuit wiring, damage any attached appliances, and create a fire risk.

5. Check That the New Fuse Is Working

Once you have changed the fuse, turn the main power back on. Occasionally the panel may spark when it’s turned back on, so wearing safety glasses as an extra precaution is a good idea. Stand to the side of the box and make sure your hands are dry and you’re not standing on a wet floor. Once you restore the power, you can test out lights or appliances in the room affected when the original fuse blew.

If they aren’t working or the fuse blows again immediately or soon after resetting, there’s likely a more serious issue that needs addressing.

6. Troubleshoot

If the fuse blows again after the reset, you don’t need to call out the electrician straight away. Maybe you have an appliance that has overheated, a dodgy light fixture, or you have just overloaded the circuit again by using too many high-powered appliances at once.

To check if a particular appliance is causing the problem, try switching things on one at a time. Sometimes an appliance may have a damaged plug or wiring, or the outlet or switch connection could be troublesome. 

If this process of elimination doesn’t solve the problem, it could be a bigger wiring issue or a problem with the fuse box that necessitates a complete replacement.

When to Call a Certified Electrician

Sometimes replacing a blown fuse won’t be enough, and calling a local certified electrician for further investigation or repairs will be necessary.

If your fuses are regularly blowing even when you aren’t overloading the system, this is usually a sign that something more serious is happening.

Electrical services attached to fuse boxes are typically pretty old, and sometimes they won’t provide enough power for a modern home. If you’re regularly experiencing blown fuses, upgrading to a circuit breaker box with additional power is a sensible investment. On average, it costs around $1,000, but the cost to upgrade to a circuit breaker box can be considerably more if you want to dramatically increase the amperage capacity for your home.

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