Fuses and Circuit Breakers

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We often hear about fuses and circuit breakers but are they the same?  What are the differences?  We take a quick look at both here.

Although we sometimes use the terms interchangeably, fuses and circuit breakers aren’t the same things.  Both protect electrical circuits from dangerous overloads by interrupting the flow of electricity.  How they do so, however, is very different.

Fuses

Updated Fuse Box

Updated Fuse Box

 

There are many types of fuses.  The most common consists of a metal wire or filament that is encased in metal and glass or ceramic.  These screw into an opening in the electrical panel.  Another type of fuse is the tubular style fuse, or cartridge fuse, that is snapped into slots in the electrical panel.

Fuses are typically plugged into a fuse box, which serves as a central location for all the building’s wiring.  Normally, the fuse permits electricity to move across the filament and between circuits.  In the event of an overload, the filament melts and stops the flow of electricity.  This happens relatively quickly, meaning a fuse can stop power surges or electrical shorts in a very short time.  Once this happens, the fuse is “blown”  and cannot be used again.  It must be replaced.

Fuses are built to handle different capacities of electricity.  The size of the wire inside the fuse dictates this.  The dangers of using a fuse that has a lower capacity than is needed results in a burnt-out fuse.   A fuse that’s rated much too high for the circuit’s  needs is also a concern.  These can result in dangerous overheating of the wire and cause a fire.  Care should always be used when selecting and installing fuses.  If you’re uncertain about how to manage your fuses or electrical panel, consult an experienced electrician.

Circuit Breakers

A typical circuit breaker panel.

A typical circuit breaker panel.

 

Circuit breakers are usually located in a cabinet of switches called a breaker box.  There are two broad types of circuit breakers:  those with an electromagnet (or solenoid) and those with a bi-metal strip.  

Both types of circuit breakers create a bridge between the device’s two terminals (top and bottom).  When the circuit breaker is turned on, electricity passes between the terminals.  If the current level becomes too high, the magnetic force of the solenoid becomes strong enough to move a metal lever within the switch.  This breaks the flow of electricity.  In models with bi-metal strips, the strip bends when there is too much electricity moving through it, throwing the switch.  In either type, once the current is broken the switch may be pushed back and electricity begins flowing again.

Circuit breakers are also used in ground fault circuit interrupter (GFCI) outlets.  You can find out more about these in our blog here.

Circuit breakers can be reset quickly and easily, even in darkened rooms.  It’s also easy to tell which circuit has been affected by an overload.  The circuit breaker’s  handle is through to the “middle position,” different from all the other circuit breakers.  Circuit breakers don’t typically get “blown” like fuses and can be reused indefinitely.  However, they are more complex.  When a problem occurs circuit breakers are more expensive to replace.

If you have questions or concerns about your home’s fuses or circuit breakers, McCauley Electrical Service can help.  Give us a call at 678-362-2881 to discuss your needs.  If you have any feedback you’d like to share, please leave  a review through Google.  Hearing from our customers helps us give deliver the best service possible!