If your home was built before 1965, there’s a good chance that you have a fuse box instead of a modern circuit breaker. What does that mean for you? When there’s a blown fuse, you must go beyond simply resetting or troubleshooting the circuit breaker – instead, you’ll have to actually identify and replace the fuse.
This could be an all-too-common problem: Faulty appliances, short circuits, and overloaded circuits can all result in a blown fuse.
Fortunately, you can fix this simple electrical system issue yourself if you take the proper precautions — and I’m here to help with this how-to guide on how to identify and replace a blown fuse. Or you can ask an electrician to complete the electrical repairs if you’re not comfortable with that thought.
How Can You Tell If Your Fuse Is Blown?
A loss of power in just one area of your home is the first sign that you likely have a blown fuse. Once that happens, it’s time to do a little investigating to confirm your suspicions. Here’s what you need to know to do that effectively.
Signs Your Fuse Has Blown Out
You must visually inspect the fuse to see if it has blown. Household electrical fuses typically look like a cylinder or plug with a glass window in the middle or on top. In that window, you should see a thin metal strip without any breaks or discoloration.
The thin metal strip breaks apart when the fuse blows, terminating the electrical connection. Sometimes, the metal strip will also melt and discolor the glass window. If that happens, you might notice a burnt smell when you approach the fuse box, also known as an electrical panel.
How to Locate and Inspect Your Fuse Box
Before inspecting the fuses, you must locate your vintage electrical panel. Every home is different, so you’ll need to look in the:
- Garage
- Basement
- Laundry room
- Closets
- Attic
You might even find the fuse box outside your house near the electricity meter. If you need help finding it, ask an electrician or review your home inspection report.
Electrical Safety Considerations
To stay safe while identifying and replacing blown fuses, remember to:
- Turn off and unplug the lights, appliances, and other electrical devices in the area that lost power.
- Only work in dry conditions while wearing rubber-soled shoes and insulated gloves.
- Pull the main fuse block out of the panel before checking any of the other fuses.
Never move forward with a DIY project, especially electrical, if you feel uncomfortable with any step in the process. Call an electrician or other home improvement professional for help instead.
Common Types of Vintage Fuses
Fuse boxes in older homes usually have both cartridge and plug fuses. The cartridge fuses go in the fuse blocks and the plug fuses connect to each electrical circuit in the home. The exact configuration depends on local electrical codes and regulations, the age of your home, and builder preferences.
For residential use, you can find the following fuses rated at 15, 20, and 30 amps. The exact ones you’ll need depend on what your household wiring can handle.
Cartridge Fuses
Cartridge fuses are glass cylinders with metal contact points at each end. Ferrule-type fuses have caps with a flat end surface, while knife-blade styles have a flat metal blade poking out. You’ll find ferrule-type fuses most often in older homes.
You’ll find cartridge fuses in the main fuse blocks and circuits running large appliances, like air conditioners. They’re rated at up to 60 amps to properly handle the electricity coming into your home from the power lines.
Plug Fuses
Plug fuses have a short, cylindrical glass or ceramic body with a screw-in base, similar to a lightbulb. There are three main types of plug fuses:
Standard fuses simply thread into the regular socket to complete the circuit. They all have the same size bases, so you have to be mindful about which fuse you’re using to prevent fire hazards.
Tamper-resistant fuses have plastic, screw-in bases that vary in size depending on the amperage. A fuse adapter only accepts the correct fuse sizes, helping prevent you from installing the wrong one.
Time-delay fuses come in either standard or tamper-resistant styles. They’re designed to tolerate brief power surges without popping. That way, you can use them for appliances that demand a lot of power at startup.
How to Pull and Inspect Your Fuses
Both cartridge and plug fuses easily disconnect from the electrical box for a quick inspection. Just follow these steps to check for a broken fuse.
Cartridge Fuses
- Pull the fuse block out of the panel by the handle
- Use a fuse puller to lift the cartridge out of the block
- Look in the glass window to check for a broken or burnt metal strip
Plug Fuses
- Pull the main fuse block to keep power from going through the panel
- Twist the plug fuse counterclockwise to remove it from the panel
- Look in the glass window on top of the fuse to check the metal strip
Install a new cartridge or plug fuse if the metal strip looks broken, burnt, or otherwise damaged.
How Should You Fix a Blown Fuse?
Upon finding a blown fuse, you’ll need to replace it to restore power to that area of your home.
How to Replace a Blown Fuse
You’ll follow the same basic steps no matter what type of fuse you need to replace. To begin, go over the safety precautions above to ensure you’re ready to move through the replacement steps. Also, get a replacement fuse that’s the correct type and amperage rating for the socket.
Then, you’ll need to:
- Put on your rubber-soled shoes and insulated gloves
- Pull the main fuse block out of the panel to disconnect the power
- Remove the blown fuse by twisting it out of the socket or using a fuse puller
- Replace the blown fuse with a new one by screwing it in or pushing it into place
- Slide the main fuse block into the socket and press it in firmly
Upon completing those steps, you can close the panel door and check if replacing the fuse has fixed the problem. If not, you may need to call an electrician to take a look.
All standard plug fuses have the same size base, so it’s possible to install the wrong fuse. The fuses currently installed in your fuse box might not be the correct amperage as a result.
In most old homes with vintage fuse panels, a 30-amp fuse is a red flag that you might have too much power running through the circuit. Since this is a serious fire hazard, it’s always important to assess your electrical wiring to find the correct fuse.
Generally, 14-gauge wiring supports a 15-amp fuse, while a 20-amp fuse needs 12-gauge wiring. Although you could play it safe with a 15-amp fuse, it’s best to consult an electrician if you’re unsure which fuse to select.
How Do You Prevent Fuses from Blowing Again?
Household fuses blow for three main reasons: An overloaded circuit, a short circuit, or a faulty appliance.
Overloaded Circuit
An overloaded circuit is the most common cause and the easiest to fix. You just have to decrease the load on that particular circuit by moving appliances or electronics to a different area of your home. If that’s not possible, you may need to upgrade to a modern breaker box. If that’s in the cards, bring the cost down by looking into government rebates and tax credits for energy efficiency improvements.
Short Circuit
A short circuit occurs when the electricity flowing through your home takes the wrong path and suddenly increases the flow of current. This issue points to a problem with your wiring and requires professional diagnosis and repair by a licensed, bonded, and insured electrician.
Faulty Appliance
If you have an appliance on the fritz, its electrical load may increase, resulting in a blown fuse. The fuse pops to protect the circuit from overheating and prevent fires. Repairing or replacing the appliance can halt this electrical problem in its tracks.
So, Can You Fix a Blown Fuse Yourself?
You can definitely fix a blown fuse yourself if you have the right replacement fuses and feel comfortable moving through the inspection and repair steps. Once you inspect the fuses, you’re halfway to fixing it anyway, so you might as well give it a try at that point.
A professional electrician is only a quick phone call away, though, if you decide that this DIY project just isn’t for you. Also, remember to hire a professional if you suspect that a short circuit or other wiring issue keeps popping your fuses.
If you have an excellent home warranty, your policy may cover the cost of electrical repairs and replacement of major appliances. Coverage varies depending on the company and policy type, so check with your provider if you think they might help.