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How to Check for Blown Fuses

Updated April 17, 2017

A fuse box helps to protect the electrical system of your home. The box contains a fuse for each circuit in your home, and can stop current from flowing in the circuit if an electrical short or overload occurs. The fuse stops the flow of current by burning a small wire inside of itself, breaking the circuit. When the wire inside the fuse is burnt, this is called a blown fuse. If you lose power in part of your home, check the fuse box for blown fuses.

Make sure that it is safe to work in the fuse box. Unplug all devices in the area of your home where you lost power. If the fuse box has a master power switch, turn off power to the fuse box before you begin to work with the fuses inside. Never work with fuses on a live circuit.

Remove the fuse you think is blown and visually inspect it. Some fuses will have glass sections where the wire will be visible. If you can see that the wire has burnt and is broken in the middle, the fuse has blown. Additionally, according to the "Los Angeles Times," you may see a "dark or burnt spot in the centre of any of the fuses," if they are blown.

Use a multimeter to check the resistance of the fuse. If you cannot see the wire or it does not appear to be broken, a multimeter can check the fuse electronically. Set the multimeter to the lowest setting for measuring resistance in ohms. Touch one probe to one side of the fuse, and the other probe to the other side. If the multimeter shows 0 ohms, the fuse is good. If the meter shows infinity or overload, the fuse has blown.

Replace the fuse if it is blown. If the fuse is not blown, check other fuses in the fuse box. If no fuses appear to be blown, there is something besides a blown fuse at fault.

Tip

When using a multimeter to check a fuse, don't worry if you get a reading of 1 or 2 ohms. The fuse is still good.

Warning

If you do find a blown fuse, always replace it with a fuse of the exact same rating.

Things You'll Need

  • Multimeter
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About the Author

David Somerset has been a writer intermittently for 11 years. He attended New Mexico Tech and earned a Bachelor of Science in technical communication in 2007. From being published in the "Bucksworth Community News" to writing how-to articles for eHow, his experience is quite diverse.