Blow a Fuse
Pedagogically reviewed by LexFizz Team
To suddenly become very angry and lose your temper.
Quick meaning: If you “blow a fuse,” you suddenly lose control of your temper and explode with anger. It describes a fast, dramatic outburst — like an electrical fuse blowing when the current becomes too much to handle.
Meaning
To blow a fuse means to suddenly become extremely angry, often shouting or reacting strongly. The anger usually comes out all at once, after a build-up of frustration or after one final thing pushes the person past their limit. It suggests a loss of self-control rather than calm, measured annoyance.
The image behind the phrase is electrical. Just as a fuse breaks the circuit when too much current flows through it, a person “blows a fuse” when the emotional pressure becomes too great. The outburst is sudden and noticeable, and it usually surprises the people around them.
The idiom is close in meaning to other anger expressions such as “hit the roof,” “lose it,” or “fly off the handle.” It is everyday and informal.
Origin
This idiom comes directly from electrical engineering. A fuse is a small safety device containing a thin wire. When too much electrical current passes through a circuit, the wire heats up and melts — it “blows” — breaking the connection suddenly and dramatically to prevent damage or fire.
From the early 20th century, as household electricity became common, people began using the phrase figuratively. A person overloaded with stress or anger was compared to an overloaded circuit: when the pressure became too much, they “blew a fuse” and the calm connection broke all at once. Idioms like this are the kind of expression documented in general reference works such as the Cambridge Dictionary, which record how figurative meanings develop in everyday English.
The vivid, instantly recognisable image — a sudden snap after too much pressure — helped the expression spread quickly into everyday English on both sides of the Atlantic.
Example Sentences
When he saw the scratch on his new car, he completely blew a fuse.
Try not to blow a fuse in the meeting — stay calm and explain your point politely.
My boss blew a fuse when she realised the report had been sent to the wrong client.
Dialogue Example
A: Did you tell Dad you crashed the car?
B: Not yet. I’m waiting for the right moment — if I tell him now, he’ll blow a fuse.
Usage Notes
This idiom is informal and used in both British and American English. It is most common in spoken language and casual writing. You will often hear it with intensifiers such as “completely” or “totally,” and it is frequently used as a warning (“don’t blow a fuse”) or a prediction of someone’s reaction.
Common Mistakes
Learners sometimes say “blow the fuse” or “blow up a fuse.” The standard form uses the indefinite article: blow a fuse. Also, do not confuse it with the separate phrasal verb “blow up,” which can mean to explode literally or to inflate something — though “blow up” can also mean to lose one’s temper.
Related Idioms
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Quick Check: Blow a Fuse
2 questions — test what you just learned.
1. What does “Blow a Fuse” mean?
2. Complete the sentence: “Try not to _____ in the meeting — stay calm and explain your point politely.”
Frequently Asked Questions
What does “blow a fuse” mean?
It means to suddenly become very angry and lose your temper, often with a dramatic outburst after a build-up of frustration.
How do you use “blow a fuse” in a sentence?
You can say “he blew a fuse” or “don’t blow a fuse.” For example: “My boss blew a fuse when she saw the mistake.”
Where does “blow a fuse” come from?
It comes from electrical fuses. When too much current flows through a circuit, the fuse’s wire melts and the connection breaks suddenly. People compared this dramatic break to a person suddenly losing their temper.
Is “blow a fuse” formal or informal?
It is informal. It is common in everyday conversation and casual writing but is not suited to formal reports or academic writing.
What are some synonyms for “blow a fuse”?
Similar idioms include “hit the roof,” “fly off the handle,” “lose your cool,” “see red,” and “blow your top.”
Is it “blow a fuse” or “blow the fuse”?
The idiomatic form is “blow a fuse” with the indefinite article “a.” “Blow the fuse” sounds literal, as in an actual electrical fuse.
Is this idiom used in American English?
Yes. It is used in both British and American English and is widely understood by speakers everywhere.
Does “blow a fuse” suggest a sudden or gradual reaction?
It suggests a sudden reaction. The anger usually comes out all at once, often after a build-up of pressure, just like a fuse blowing instantly when overloaded.
Can you use “blow a fuse” as a warning?
Yes. You can say “don’t blow a fuse” to warn someone to stay calm, or “he’ll blow a fuse” to predict an angry reaction.
What English level is “blow a fuse” suitable for?
It is pitched at B1 (Intermediate) level. It is a common, accessible idiom that intermediate learners can use confidently in everyday speech.