Guide · updated 10 November 2026
How to Test a Fuse with a Multimeter
To test a fuse, switch the circuit off, take the fuse out of its holder, set the multimeter to continuity (or the lowest ohms range) and touch one probe to each end cap. A good fuse beeps and reads close to 0 Ω. A blown fuse stays silent and reads OL. Testing the fuse out of the circuit is the reliable way, because other components in the circuit can give a false reading.
iPhone and iPad (iOS 17 or later): free on the App Store. Android later.
Safety first
Safety. Switch the circuit off and isolate it from power before you touch the fuse. Never measure resistance or continuity on a live circuit. Discharge any capacitors in the equipment first, through a resistor. Replace a blown fuse only with one of the same type and rating, and find out why it blew. Use a meter whose CAT rating and fuse fit the place you are working.
What you need
- A multimeter with continuity or ohms, such as the OWON OW18B.
- The fuse, out of its holder. A glass fuse can also be checked by eye.
- The circuit switched off and isolated.
Steps
- Switch the equipment off and unplug it or disconnect the battery.
- Take the fuse out. Use a fuse puller or insulated pliers for a car-type blade fuse.
- Probes into COM and V/Ω. Dial to the continuity symbol, or to ohms on the lowest range.
- Touch the probe tips together and note the value; it is the lead resistance. Press REL if you want it taken off the readings.
- Touch one probe to each metal end of the fuse (the blades of a blade fuse, the caps of a cartridge fuse).
- Read the meter: beep and a value near zero is good, silence and OL is blown.
What the reading means
Typical values; meters differ.
| Reading | Typical meaning |
|---|---|
| Beep, 0 to a fraction of an ohm | Good fuse |
| OL, no beep | Blown fuse: the element is open |
| A few ohms or a reading that wanders | Poor contact on the end caps, or a damaged fuse; clean the ends and test again, and replace it if in doubt |
A small fuse has a very low resistance, from a few milliohms for a large one up to some ohms for a fine, low-rated one, so the exact number varies with the rating. The point of the test is open or not open.
Common mistakes
- Testing the fuse in the circuit. Parallel paths through other components can make a blown fuse beep. Take it out.
- Testing with the power on. Resistance mode on a live circuit is a hazard to the meter and to you.
- Probing the plastic or the paint on a blade fuse. Touch the metal.
- Fitting a bigger fuse because the right one keeps blowing. The fuse protects the wiring. Find the fault.
- Judging by looks. A fuse can be blown with no visible mark, and a darkened glass can still be good.
- Forgetting the meter's own fuse. If a current range reads zero or OL on a known-good source, the meter's fuse may be the one that has blown.
Log the result with a Bluetooth meter
When you check many fuses, for example in a panel or a fleet, a Bluetooth meter and the app save the notebook. The app reads the meter live, and one tap saves the reading with a note or photo, such as the fuse position. Hold keeps the reading on screen once the fuse is out of your hand. A reading from a meter the app does not read can be typed in and is marked as manual. Export the session as CSV. See quick capture and hold, REL, min and max. A test file is your record, not a certification.
What the app does here, and what it doesn't
| What it does | Plan |
|---|---|
| Type the reading from any instrument; typed values are marked as manual. | Free |
| Hold freezes the displayed reading and statistics in the app, independent of the meter's own HOLD. | Free |
| REL shows the difference from a stored reference, for example to null out test-lead resistance. | Free |
| One tap saves the current reading, with an Undo. | Free |
| Export log sessions and test files as CSV, free. | Free |
Not yet, or not planned
- A test file is your record, not a certification.
Questions
Can I test a fuse without removing it?
You can try, but the result is not reliable. Other parts of the circuit can create a path around a blown fuse. Remove it, or at least lift one end, for a trustworthy result.
Should a good fuse read zero ohms?
Close to zero. A good fuse reads a very small resistance, often below an ohm, plus your lead resistance. A beep or a near-zero value means good, OL means blown.
What if the fuse tests good but the device is dead?
The fuse may be open only under load, or the fault is elsewhere. Check the supply, the holder contacts and the wiring with the power off, then re-test under the conditions in the equipment's manual.
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