Quick answer Set the multimeter to continuity (the sound-wave symbol). Touch one probe to each end of the fuse. A beep means the fuse is good; silence means it is blown and needs replacing.

On this page

  1. Fuse types
  2. The continuity test
  3. Reading the result
  4. Appliance fuses
  5. FAQ
  6. Four fuse-testing mistakes
  7. Finding the fuse in an appliance
  8. Testing a fuse, step by step
  9. Fuse types you will meet
  10. Replacing a fuse correctly
  11. Why a fuse blows
  12. What you need

Fuse types you will meet

The test is the same for all of them, but you need to know what you are looking at.

TypeWhere it isLooks like
Glass cartridgeInside appliances, older electronicsClear glass tube with a wire
Ceramic cartridgeHigh-current appliancesOpaque white/ceramic tube
Blade fuseCars, some appliancesColoured plastic with two blades
Control-board fuseOn the appliance circuit boardSmall, often soldered or in a holder
Plug fuseUK-style plugsCeramic with a screw cap
Common fuse types

The continuity test

  1. Unplug the appliance and remove the fuse from its holder.
  2. Set the multimeter to the continuity setting (the sound-wave icon) or the lowest resistance range.
  3. Touch one probe to each metal end of the fuse.
  4. Listen for the beep and read the display. A beep (or a reading near 0 Ω) means the fuse is intact.
  5. If there is no beep and the display shows OL or 1, the fuse is blown.
Always remove the fuse first Testing a fuse in-circuit can give a false reading, because the meter may find a path around the fuse through the rest of the circuit. Pull it out and test it on its own.

Reading the result

ReadingMeaningAction
Beep / ~0 ΩFuse is goodLook elsewhere for the fault
OL / 1 / no beepFuse is blownReplace with the same rating
Intermittent beepFuse is failingReplace it
Blackened glassFuse blew hardCheck for a short before replacing
How to interpret a fuse test

A fuse that has blown hard — blackened glass, a scorched holder — usually means something downstream shorted. Replacing the fuse without finding the short will just blow the new one.

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Appliance fuses

This is where a generic electronics guide stops. In an appliance, the fuse you are looking for is usually not the obvious one:

  • Control-board fuse: a small fuse on the main board, often soldered. It protects the electronics, not the motor. If the board is dead but the appliance has power, test this first.
  • Thermal fuse: a one-shot fuse that opens when the appliance overheats. Common in dryers and microwaves. It looks like a small cylinder with two leads.
  • In-line fuse: a fuse in the power cord or harness, hidden under a cover.
  • Plug fuse: in UK-style plugs, the easiest one to check and replace.
Replace like for like Always replace a fuse with the same amperage and type. A higher-rated fuse will not protect the appliance and can cause a fire. If the correct fuse keeps blowing, the fault is elsewhere — stop and diagnose.

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Four fuse-testing mistakes

  1. Testing in circuit. The meter can find a path around the fuse through the rest of the circuit. Remove the fuse and test it on its own.
  2. Using the wrong setting. Continuity is the fast test; resistance works too. Voltage will not tell you whether a fuse is blown.
  3. Replacing with a higher rating. A higher-rated fuse will not protect the appliance and can cause a fire. Always match the rating.
  4. Replacing without finding the fault. A fuse that blew hard means something downstream shorted. The new fuse will blow too.

Finding the fuse in an appliance

In an appliance, the fuse is often not where you expect. Work through these locations:

LocationWhat it protectsHow to find it
Control boardThe electronicsSmall fuse on the board, often soldered
Power cord / harnessThe whole applianceIn-line fuse under a cover
Thermal fuseOverheat protectionCylinder with two leads, near the heater
Plug (UK)The whole applianceInside the plug, behind the fuse cover
Where to find fuses in an appliance

If the appliance is completely dead — no lights, no sound — the control-board fuse or the in-line fuse is the first thing to check. If it powers on but will not heat or run, the thermal fuse is the likely culprit.

A thermal fuse is one-shot A thermal fuse opens permanently when the appliance overheats, and it cannot be reset. If it has blown, the appliance overheated for a reason — usually a blocked vent or a failed fan. Fix that before replacing the fuse.

Testing a fuse, step by step

A fuse test is the fastest diagnostic in appliance repair. It takes under a minute.

  1. Unplug the appliance and remove the fuse from its holder.
  2. Set the meter to continuity (the beep symbol) or the lowest resistance range.
  3. Touch the probes together to confirm the meter beeps.
  4. Touch one probe to each end of the fuse.
  5. Listen and read. A beep and near-zero ohms means the fuse is good.

If the meter does not beep and the reading stays at infinity, the fuse is blown. There is no middle ground with a fuse — it either conducts or it does not.

Fuse types you will meet

TypeLooks likeWhere
Glass cartridgeClear tube with a wireOlder appliances, plugs
Ceramic cartridgeWhite tubeHigh-current appliances
Blade fuseColoured plasticCars, some appliances
Thermal fuseSmall cylinder, two leadsNear heaters and motors
SMD fuseTiny chip on a boardControl boards
Fuse types in appliances

A thermal fuse is different from the others: it opens permanently when the appliance overheats, and it cannot be reset. If a thermal fuse has blown, the appliance overheated for a reason — usually a blocked vent or a failed fan. Fix that before replacing the fuse, or the new one will blow too.

Replacing a fuse correctly

Always match the rating exactly. A fuse is rated in amps and volts, and both matter. A higher-rated fuse will not protect the appliance and can cause a fire; a lower-rated one will blow immediately. If the replacement blows straight away, stop — there is a short circuit downstream, and replacing fuses will not fix it.

Why a fuse blows

A fuse is a deliberate weak point. It melts to protect the rest of the circuit, so a blown fuse is a symptom, not the disease.

Blown howLikely cause
Clean break, no blackeningAge or a brief overload
Blackened glass, heavy depositA short circuit downstream
Blown immediately on replacementA persistent short — stop and find it
Thermal fuse openOverheating — blocked vent or failed fan
What a blown fuse tells you

A fuse that blows the instant you replace it is telling you there is a short circuit. Replacing it again will not help. Find the short first — a pinched wire, a failed component, or a burnt connector — then replace the fuse.

What you need

A basic multimeter with a continuity setting is all you need, plus a set of replacement fuses in the right ratings. Buy an assortment box so you have the correct value on hand, and never substitute a higher rating — a fuse that does not blow is a fire risk, not a fix.

Frequently asked questions

How do I test a fuse with a multimeter?
Set the meter to continuity, remove the fuse, and touch one probe to each end. A beep means the fuse is good; no beep means it is blown.
What reading means a fuse is blown?
OL, 1, or no beep on the continuity setting. A good fuse reads near 0 ohms and beeps.
Can I test a fuse without removing it?
You can, but the reading may be wrong because the meter can find a path around the fuse through the circuit. Always remove the fuse to test it properly.
Why does my appliance keep blowing fuses?
A fuse that blows repeatedly means there is a short or an overload downstream. Replacing the fuse will not fix it — you have to find the fault, or the new fuse will blow too.
Can I replace a fuse with a higher-rated one?
No. A higher-rated fuse will not protect the appliance and can cause a fire. Always use the same amperage and type, and if it keeps blowing, diagnose the underlying fault.
Bottom line Pull the fuse, set the meter to continuity, and listen for the beep. If it is silent, replace it with the same rating — and if the new one blows, stop and find the short.
A

Apartment Air Fix Editorial Team

We test and write about the appliances that break in apartments. Our recommendations are based on hands-on use, manufacturer specs and verified owner reviews — never on commission rates.

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