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Fuses are safety devices which sacrifice themselves rather than allow too much current to flow through a circuit.  Installed in home electrical panels built before 1960, fuses protect the home wiring from overheating and starting a fire.  Today circuit breakers perform that same function and more in a much more convenient form.  However, there are many old homes that have not been upgraded and still use fuses

You might be surprised to find that fuses for other purposes are still very much in use today.  Electronics equipment is typically fuse protected, as is your car’s electrical system.  Even Christmas lights often have a fuse holder with a tiny glass fuse installed.  At The Home Depot, we still sell a variety of fuses in different styles, types and amperage ratings.

How do Fuses Work?

Fuses work by adding a small resistance in series to a circuit at a critical point inside the fuse.  As current flows through the circuit, that critical place inside the fuse heats up.  When the current flow exceeds the fuse’s amperage rating, that critical weak spot will melt away and disconnect the power from the circuit.  In many cases, the blown fuse gives a visual indication of its demise.

The upper fuse shows where that critical weak spot is located, and the lower fuse is clearly a goner.  No fixing them either, as fuses must be replaced once blown.  It is always a good idea to try and determine why a fuse blows, correcting the problem before replacing and blowing up another fuse.  One thing that should never be done is to replace a fuse with another that is rated for higher amperage.  This negates the circuit protection the fuse provides. 

Types of Fuses

The picture above shows the styles of fuses typically installed in a home fuse panel.  Time delay fuses are designed to allow short bursts of overcurrent, and are commonly used in circuits that have large electric motors.  Plug fuses have a glass top and can either use a standard Edison base or a tamper proof type S base.  Cartridge fuses usually have no visual condition indicator, and are typically used in higher amperage circuits.  Glass fuses like the pair shown above are not used in home panels, but are frequently found in electronics equipment as well as in much older cars and trucks.  ATC fuses like the ones shown below are frequently found in cars today.

Home Fuse Panels

Does your home still have a fuse panel?  If so I would suggest that you consider having it upgraded to a circuit breaker panel.  New circuits can be run, and the existing circuits can be split up to better handle the higher electrical demands that modern living standards dictate.  Not only will you be able to easily reset a tripped breaker, but the likelihood of the breaker tripping in the first place will be much lower.  In addition, you will no longer need to buy replacement fuses.




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Posted 2015-11-24T21:32:36+0000  by Chris_HD_CHI Chris_HD_CHI