Last Updated: March 23, 2026
What You’ll Need
- Small Phillips or flathead screwdriver (to open battery/fuse compartment)
- Replacement fuse (correct voltage rating, current rating, and physical size)
- Multimeter (a second meter or this same meter in continuity mode to test the fuse)
Safety Precautions
- Remove probes from all circuits before opening the meter: Ensure the meter is not connected to any circuit before disassembling
- Use only the correct replacement fuse: Never substitute a fuse with a higher current rating “to prevent blowing.” The fuse rating is a safety specification. A fuse rated too high won’t protect the meter’s current shunt from being destroyed
- Never use a wire, coin, or other bypass in place of a fuse: Bypassing the fuse removes the only protection between your measurement circuit and a dead short — a potentially dangerous situation
- Replace with exact specifications: Same physical size, same current rating (10A, 500mA, 200mA), and same or higher voltage rating (250V, 600V, 1000V)
How to Confirm a Blown Fuse
Symptom: Current Measurement Reads 0A
The clearest symptom of a blown fuse is the meter reading 0A on every current measurement, even when you know the circuit has current flowing. This happens because the blown fuse opens the current path through the meter — no current flows through the shunt resistor, so the meter reads zero.
Test the Fuse with Continuity Mode
Remove the fuse from the meter (see below). Set the meter to continuity mode ())) symbol). Touch probes to each end of the fuse. A good fuse beeps — continuity through the fuse element. A blown fuse reads OL — the element has burned through and opened the circuit. See our guide on how to test continuity with a multimeter.
Step-by-Step: Replace the Multimeter Fuse
Remove probes from any circuit and turn off the meter
Ensure the meter is completely disconnected from all circuits. Remove the test probes from the meter sockets if desired.
Open the battery/fuse compartment
Most multimeters have a compartment on the back secured by one or two Phillips screws. Some meters have a separate fuse access door. Remove the screws and lift the cover. On some models, the battery and fuse compartment are combined.
Locate the fuses
Most multimeters have two fuses:
- High current fuse (10A or similar): Protects the high-current measuring range. Located near the 10A input socket. Commonly a 10A/600V ceramic fuse.
- Low current fuse (200mA, 500mA, or similar): Protects the milliamp range. Common size is 500mA/600V glass fuse.
Remove the blown fuse
Most fuses clip into spring-loaded holders — pry gently with a flathead screwdriver or use the probe tip to pop one end out. Some ceramic fuses are cylindrical — simply pull straight out from spring clips.
Test the removed fuse
Test the removed fuse with continuity mode or resistance mode. No beep / OL = blown. Beep / near 0Ω = still good (meaning the problem is elsewhere — check meter probes and wiring).
Read the fuse specifications
Read the marking on the side of the fuse. Common formats:
- 0.5A / 600V or 500mA 600V = 500mA fuse, 600V rating
- 10A / 600V = 10A fuse, 600V rating
- F500mA = “Fast blow” 500mA fuse
- T500mA = “Time delay / slow blow” 500mA fuse
Physical size also matters — most multimeter fuses are 5mm × 20mm (standard European size) or 6.3mm × 32mm (larger American size).
Buy the correct replacement
Match: current rating, voltage rating, physical size, and fuse type (fast blow vs slow blow). Use the same or higher voltage rating — never use a lower-rated voltage fuse. Available at hardware stores, electronics suppliers (Mouser, Digikey, Amazon), and electrical supply shops.
Install the replacement fuse
Snap or press the new fuse into the fuse holder in the same orientation as the old one. Polarity doesn’t matter for fuses — either direction works.
Close the compartment and test
Replace the cover and screws. Insert probes. Test current measurement on a known circuit — the meter should now read correctly.
Common Multimeter Fuse Sizes and Ratings
| Fuse Location | Common Rating | Physical Size | Common in |
|---|---|---|---|
| High current (A) port | 10A / 600V or 1000V | 5×20mm or 6.3×32mm | Most consumer meters |
| Low current (mA) port | 500mA or 200mA / 600V | 5×20mm | Most consumer meters |
| Fluke 87V (mA) | 440mA / 1000V (special) | 5×20mm | Fluke 87V series |
| Klein MM300 (mA) | 500mA / 600V | 5×20mm | Klein MM series |
Always check your specific meter’s user manual for fuse specifications — ratings vary by model.
Why Do Multimeter Fuses Blow?
- Measuring voltage with probes in amperage port: The most common cause. If you connect the A port directly to a voltage source, the low-resistance current shunt creates a near-short and blows the fuse
- Measuring current exceeding the fuse rating: Selecting the 200mA range when the circuit draws 3A blows the mA fuse. Start on the highest range
- Forgetting to move probe from A port to VΩ: Measuring voltage after current measurement without switching probes blows the fuse
- Accidentally touching a 120V outlet: If the meter was left in current mode and probes touched an outlet
Pro Tips
- Keep spare fuses in your toolbox: Most fuses cost $1–$3 each. Carry two spare 10A fuses and two spare mA fuses for your meter model
- Check fuse before accusing the circuit: If your current measurement suddenly reads 0A on a circuit you know is live, suspect the fuse before assuming the circuit is dead
- Buy manufacturer fuses for safety-critical meters: Fluke, Klein, and Amprobe sell replacement fuses with proper voltage ratings. Third-party fuses may have lower-than-claimed voltage ratings, especially the 1000V Fluke fuses
- Consider a CAT III/IV meter: Higher-category rated meters use fuses with higher voltage ratings that are harder to bypass or compromise. Worth the investment for professional use
Frequently Asked Questions
Why does my meter read 0A even after replacing the fuse?
Check probe placement — the red probe must be in the A port (10A or mA), not the VΩ port. Also verify you’re using the correct meter mode (A~ or A=). If still 0A with correct probe position and mode, the meter’s internal current shunt (the resistor the fuse protects) may be damaged from a high-energy fault that the fuse didn’t clear fast enough.
Can I use any fuse with the same current rating?
No. The voltage rating matters significantly. A 10A / 32V fuse looks identical to a 10A / 600V fuse but will fail dangerously on 120V AC. Always match or exceed the voltage rating. The physical size must also match exactly — a shorter fuse won’t make solid contact in the holder.
What’s the difference between fast blow (F) and slow blow (T) fuses?
Fast blow (F) fuses trip almost instantly on overload. Slow blow (T) fuses tolerate brief current surges (motor start, capacitor charge) before tripping. Use the same type as the original — using a slow-blow where a fast-blow is specified reduces overcurrent protection speed.
How do I find fuse specs if there’s no marking on the fuse?
Check the meter’s user manual (usually available as a PDF from the manufacturer’s website) or look inside the fuse compartment for a printed label specifying fuse ratings. Search “[meter brand model] fuse specification” for your specific model.
Conclusion
A blown multimeter fuse is a quick fix — usually a $2 fuse and 5 minutes of your time. The important steps are confirming it’s the fuse (not just wrong probe placement or mode), reading the exact specifications off the old fuse, and replacing with an exact match. Keep spares on hand for both fuse positions in your meter, and the next blown fuse won’t interrupt your work for more than a minute.
