Difference Between Ceramic & Glass Fuses

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There are so many fuses to choose from these days that find their way into all the little lights, motorized toys and decorative items in your home. They may look a lot alike, but each type of fuse functions differently. With all that a fuse does, it's important to know if you are using the correct one for the appliance or fixture that has blown its fuse.

Difference Between Ceramic & Glass Fuses
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Anatomy of Fuses

Electrical appliances and equipment are protected by the tiny fuses that are installed in their wiring or housing. They break the electrical circuit should something nefarious happen to the current, such as being overloaded due to a power surge during a severe storm, or if a circuit decides to short. The tiny fuse prevents the problem at the source from traveling to an expensive appliance or beloved décor item and destroying its fine electrical systems. It also keeps the item from making a bigger problem, such as fire or water damage if a machine full of wet items fails before the spin cycle. Fuses come in all shapes and sizes. They are also made of many different types of material to ensure they can function properly under various conditions fuses might confront during its relatively short duration in the appliance or fixture. The two main materials that are used to manufacture well-built fuses are glass and ceramic. The types of fuses include long-time-lag or super-time-lag (TT), fast-acting fuses (FF), quick-blow fuses (F) and slow-blow or time-lag fuses (T).

Fuses at Work

A current can become corrupted or overloaded due to accidental damage from pets or being moved, general deterioration, excessive overloading of the electrical system or exposure to the elements. If you have a fixture outdoors, the fuse may need replacing more often due to the harsh environment the tiny workhorse endures on a daily basis. Generally, a current overload happens from a temporary surge from a motor starting up or too many items on the same line. The fuse holds back the overcurrent from reaching the appliance. The body – or barrel – has a plated copper or brass tip – or terminal – at each end of the fuse. The element connects the terminals. The element is made of zinc, copper, aluminum or silver.

Ceramic Fuse

Opaque and metal tipped, a ceramic or sand fuse is fairly common for many household items, from extension cords to some ceiling fans. A ceramic fuse is built to withstand high temperatures. The more thermally stable fuse is typically filled with sand in order to prevent the conductive film from forming. The film is formed when a short circuit melts the fuse element, causing a deposit to be seen on the inside of the fuse barrel as a film.

Glass Fuse

If you can see the element or the filament in the fuse, you more than likely have a glass fuse. Glass has a low rupturing point, such as 15 amperes. If a high voltage comes down the electrical line, the fuse element will melt. The tiny glass fuses are great for small items that don't draw a heavy amount of current and blow on a regular basis. They don't perform well outdoors and can shatter when placed in high temperatures due to its low thermal stability.


Kimberley McGee is an award-winning journalist with 20+ years of experience writing for a variety of clients, including The New York Times, Las Vegas Review-Journal Home section and other national publications. As a professional writer she has researched, interviewed sources and written about home improvement, interior design and related business trends. She earned a B.A. in Journalism from the University of Nevada, Las Vegas. Her full bio and clips can be viewed at www.vegaswriter.com.

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