How to Deal With A Blown Fuse

Dealing with a blown fuse

How to Deal With A Blown Fuse

(Last Updated On: June 28, 2017)

While a large number of American homes have switched their electrical panels over to a breaker box, a great number still have fuse boxes that use fuses in order to prevent power overloads and short circuits. The result may be a blown fuse. To help, here is some general information about blown fuses and what you can do to avoid them in the future.

How to Tell If A Fuse Has Blown

It will be pretty obvious to you right away if you have blown a fuse in your home, as the switch you’re trying to flip, or the outlet you want to use, or even the appliance you’re trying to run, stops working or won’t turn on. You may also suddenly find yourself in the dark.

If you suspect you have blown a fuse, you can also go and look directly at your fuse box. If a fuse has blown, you may be able to see bits of melted metal inside the fuse, or the glass window at the top of the fuse may be discolored. If you’re still unsure if you’ve blown a fuse, you can try replacing the suspected damaged fuse with one you know is working correctly and if power is restored, then your problem is solved. Another way to test for a blown fuse is to use a tool called a multimeter, and connect the fuse to the multimeter to check for resistance. If there is resistance showing on the reader, the fuse is blown, and if no resistance registers then the fuse should still be good.

What Causes a Blown Fuse?

There are a couple of reasons a fuse is blown, including:

Electrical overload. This occurs when too much power is being drawn on a single circuit and occurs as a result of overloading the circuit. For example, you would never want to run your dishwasher and dryer on the same circuit as they both draw high amounts of power and could easily cause a circuit overload. When the circuit is overloaded, the metal ribbon within the fuse will melt, causing the electrical connection to open, thus resulting in power stopping. A qualified electrician should be able to calculate and wire safe loads for your fuse box.

Short circuit. This occurs when electrical components accidently touch or cross. This can occur anywhere along the circuit, from the wiring within your house, to the power cord of a device itself. After isolating which circuit the blown fuse is on, you will need to trace the entire length of electrical wiring on that circuit to check for any shorts. A qualified electrician can also perform this task.

You must replace a fuse after it has blown in order to restore power, as the fusible link within the unit has melted, eliminating the connection that completes the circuit and allows power to flow.

Types of Fuses

There are two main types of fuses commonly used in homes today. They are plug fuses and cartridge fuses. It’s a good idea to keep spare fuses on hand in case one blows.

Plug fuses feature a screw-in design and a glass window that lets you quickly see if a fuse has blown or not. They typically comes in 15, 20, or 30 amp sizes and are frequently used to protect 120-volt circuits. The cost of a plug fuse is typically around $2-$5, and will depend on amperage.

Cartridge fuses are cylindrical in shape and have contacts on either end that plug into the fuse box. They are frequently used to protect 240-volt circuits and often require a special tool called a fuse puller in order to be replaced. The cost of a cartridge fuse is anywhere from $10-$200, depending on specifications.

How to Replace a Blown Fuse

Replacing a blown fuse is actually a very easy task, and one that any homeowner can reasonably do themselves. The first step in replacing a blown fuse requires you to check the amperage rating of the fuse you need to replace. Newer fuse boxes have a built-in safeguard that only allows you to screw in the correct sized fuse, and helps to prevent electrical fires.

After ensuring that the device that may have tripped the fuse is unplugged or turned off, you’ll next need to unscrew the blown fuse (or pull out the cartridge), removing it from the fuse box. Take the new fuse out of the package and screw or slide it into the empty hole. That’s it — your power should now be restored. Be sure to dispose of your blown fuse according to local bylaws.

If your fuses continue to blow, you will likely need to reduce the load or check for shorts on that particular circuit in order to fix the issue. This may involve some rewiring of your home’s electrical system. This requires the skill and expertise of a qualified electrical professional and is not something homeowners should undertake themselves.

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