How to Test Electrical Fuses

Test fuses to make sure they are good.

A fuse is an electrical conductor that breaks open when more than the rated power is applied through it. Short circuits blow fuses, electrical power surges blow fuses, even high heat can melt the fuse element and break it. Sometimes the break in a fuse is so minute that it is difficult to determine, and it may leave you scratching your head because the fuse might still look good, but it is blown. Virtually any fuse, from automotive to household canister fuses, can be tested by using a multimeter.

Things You'll Need

• Multimeter
• Continuity tester

Instructions

1. Set your multimeter to the lowest resistance range, Resistance, or RX1.

2. Touch each probe to the opposite side of the fuse, or, if it is an automotive fuse, touch each probe to one of the protruding tabs.

3. Resistance will occur if the fuse is good. If there is no resistance and the multimeter reads zero (0), the fuse is bad and needs to be replaced.

4. Use a continuity tester in the same way. Touch one probe to either side of the fuse. If the continuity bulb lights up, the fuse is good. If the bulb does not light up, the fuse is bad and needs to be replaced.

References

• Bob Vila: Testing Appliance Fuses
• Dinosaur Electronics: Testing procedure for fuses
• Your How To Partner: How To Test Fuses And Light Bulbs With A Multimeter