Set your multimeter to continuity or resistance mode to check whether a fuse is blown
A multimeter is a handheld tool that measures electrical properties. To test a fuse, you switch it to either continuity mode (usually marked with a sound-wave symbol) or resistance mode (marked Ω, the ohm symbol). A blown fuse will show no continuity or infinite resistance; a good fuse will show continuity or near-zero resistance. The test takes about 30 seconds and tells you whether the fuse itself is the problem.
You do not need to remove the fuse from its holder to test it, though removing it makes the reading clearer. If you test it in place, make sure the circuit it protects is powered off first — never test a live fuse.
Key Takeaways
- Set the multimeter dial to continuity mode (sound-wave symbol) or resistance mode (Ω) before touching the fuse.
- Touch one probe to each end of the fuse; continuity mode will beep if the fuse is good, or stay silent if it is blown.
- Resistance mode shows a reading near zero ohms for a good fuse and infinity (or "OL") for a blown one.
- Remove the fuse from the holder first if the reading is unclear or if you are testing a fuse that is still in a live circuit.
- A blown fuse that looks discolored, cracked, or has a broken wire inside is visually obvious and does not need a meter to confirm.
Continuity mode: the fastest way to check a fuse
Continuity mode tests whether electricity can flow through the fuse. Turn the multimeter dial to the continuity symbol — it looks like a sound wave or a curved line with dots. This mode is designed to beep when it detects a complete path for electricity.
Place one probe tip on each end of the fuse. If the fuse is good, the meter will beep when ready. If the fuse is blown, there will be no beep and the display will show "OL" (open loop) or infinity. The beep is the quickest way to know: beep means good, no beep means bad.
Continuity mode works best when the fuse is removed from its holder, because the holder itself can sometimes interfere with the reading. If you test a fuse while it is still installed, make absolutely sure the power to that circuit is off first.
Resistance mode: an alternative if your meter has no continuity setting
If your multimeter does not have a continuity mode, use resistance mode instead. Turn the dial to the Ω (ohm) symbol, usually the lowest resistance range available — often marked 200Ω or 2kΩ.
Touch one probe to each end of the fuse. A good fuse will show a reading very close to zero ohms — usually between 0 and 5 ohms. A blown fuse will show "OL" or "infinity" on the display, meaning the meter cannot measure any resistance because no current is flowing through.
Resistance mode is slightly slower than continuity mode because you have to read a number instead of listening for a beep, but it works just as well. If the reading jumps around or is unclear, remove the fuse from its holder and test it again.
Removing the fuse before testing for a clearer reading
Fuses are held in clips or cartridge-style holders. To remove one, turn off the power to the circuit first, then gently pull the fuse straight out of its holder. Some fuses twist out; check your equipment manual if you are unsure.
Once removed, the fuse is completely safe to handle and test. Place it on a clean, non-conductive surface — a paper towel or wooden table works fine. Test it with the multimeter probes touching the metal ends or caps of the fuse.
Removing the fuse also lets you inspect it visually at the same time. A blown fuse often shows a broken wire inside the glass or ceramic body, blackening, or a visible crack. If you can see the damage, you already know it is bad and do not need the meter to confirm it.
What a good fuse reading looks like versus a bad one
A good fuse in continuity mode produces an when ready beep. In resistance mode, it shows a reading between 0 and 5 ohms. The exact number depends on the fuse type and the meter, but the key is that it is a low, stable number.
A blown fuse in continuity mode produces no beep at all — silence means the fuse is open. In resistance mode, it shows "OL" or "infinity" on the display, which means the meter cannot detect any resistance because the circuit is broken.
If the reading bounces around, flickers, or is hard to read, the fuse may be partially damaged or the probe contact may be poor. Remove the fuse, clean the metal ends with a dry cloth, and test again. If the reading is still unclear, replace the fuse and see whether the circuit works.
Why a fuse blows and when to replace it
A fuse blows when too much current flows through the circuit it protects. This usually happens because of a short circuit, an overloaded circuit, or a faulty device plugged into that circuit. The fuse is designed to break the circuit before the wiring itself overheats and causes a fire.
If a fuse blows once, replace it with a new fuse of the same amperage rating — the number is printed on the fuse body. If the same fuse blows again within days or weeks, the circuit has a real problem: either something is drawing too much power, or there is a short. Do not keep replacing fuses; find and fix the underlying cause, or call an electrician.
Never replace a fuse with one rated for higher amperage, and never bypass a fuse with foil, wire, or any other conductor. These shortcuts defeat the safety feature and put the wiring at risk of fire.
Frequently Asked Questions
Do I have to turn off the power before testing a fuse with a multimeter?
Yes, if the fuse is still in its holder. Turn off the circuit breaker or power switch that controls that fuse box first. Once the fuse is removed, it is safe to test. If you test a fuse while it is still installed and the circuit is live, you risk damaging the meter or getting a shock.
What if the multimeter shows a reading between zero and infinity?
A reading that is not quite zero and not quite infinity usually means the fuse is partially damaged or the probe contact is poor. Remove the fuse, wipe the metal ends clean with a dry cloth, and test again. If the reading is still in between, replace the fuse — it is not reliable enough to keep using.
Can I test a fuse without removing it from the holder?
Yes, but the reading may be less clear because the holder clips can interfere with the meter's signal. If you test it in place, make sure the power is off first. If the reading is unclear, remove the fuse and test it again outside the holder.
What does "OL" mean on the multimeter display?
"OL" stands for "open loop" and means the meter cannot measure any resistance because the circuit is broken. On a fuse, "OL" in resistance mode means the fuse is blown. In continuity mode, no beep means the same thing.
How do I know what amperage fuse to buy as a replacement?
The amperage rating is printed on the fuse body — look for a number like 15A, 20A, or 30A. Always replace a blown fuse with one rated for the same amperage. Using a higher-rated fuse defeats the protection and risks fire; using a lower-rated one will blow when ready.