How to identify a glass fuse

Updated February 21, 2017

Replace blown fuses with the correct size and type of fuse. Glass fuses are one of many types of fuses available on the market. The most common types of glass fuses are slow-blow fuses and fast-acting fuses. Slow-blow fuses handle a heavy power load for a short time. Fast-acting fuses blow quickly to open the electrical current. Household appliances commonly use glass fuses.

Examine the ends of the glass fuse where the metal seals the tube.

Use a magnifying glass, if necessary, to make the small printed numbers and letters on the fuses easier to read. The writing can be difficult to read without the assistance of a handheld magnifying glass.

Read the markings from left to right. The printed code at one end of the fuse has a number followed by two letters. The voltage ranking of the fuse is printed on the other end.

Determine if the letters say AG between the numbers at the one end of the fuse tube. AG is the code that signifies a glass fuse. The voltage rating of the fuse will be printed on the opposite end of the fuse. Ensure you are replacing the glass fuse with one that has the same glass rating. Failure to do so could result in serious damage.

Things You'll Need

  • Magnifying glass
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About the Author

Lynn Rademacher started writing in 2001, covering technology, family and finance topics. Her writing has appeared in "Unique Magazine" and the "Ortonville Independent," among other publications. Rademacher holds a Bachelor of Arts in mass communication from South Dakota State University.