How to Choose Between Using Fuse or Circuit Breaker

          Fuses and circuit breakers are designed with functionally the same purpose in mind—to protect the larger circuit and device from unexpected overloading which would likely permanently damage the circuit if it passed through. However, they actuate that function very differently. Both circuit breakers and fuses are designed to disrupt the flow of electricity, and few devices, if any, are more essential to the safety of your home than properly installed circuit breakers and/or fuses. The two device options are not always interchangeable for all power appliances; now to address the differences:    

(scroll to bottom of page for summarized pro & con list for electronic application)

Fuses

            Fuses are made from metal wire or filament which is enclosed in glass or ceramic with metal-casing caps and can be of residential or commercial use. When electricity flows within a closed circuit maintained by a fuse(s), the fuse will permit the power unobstructed continuity across the filament between circuits. If overloads occur the inner filament melts and abruptly stops the flow of electricity, therefore, saving the circuit and likely the greater structure from overheating or fire.

Fuses, though overwhelmingly the more inexpensive option, can only be used once then must be disposed of and replaced once blown. If the circuit is prone to frequent surges that routinely cause fuses to blow, then the fuse’s quicker reaction to the overloading can be a disadvantage in both time and money. However, when voltage and ratings are correct the fuse reacts quicker than a circuit breaker offering more protection to sensitive electronic devices.

            A fuse will only allow passing of amperage that it is rated for. If a fuse is rated for 20 amps and a surge of more than 20 amps tries to pass through the fuse, a thin strip of deliberately calibrated metal will vaporize, resulting in the circuit opening and the power shutting off. 

            In Electronic Application, fuses are typically the preferred method of protection in circuits, sensitive equipment, small electronics, etc. Fuses provide a more accurate level of protection due to the fact that fuses typically have a much more accurate reaction time, which is essential in more sensitive circuits. 

Circuit Breakers

            A circuit breaker is functionally like a modern-day fuse; a properly installed breaker panel is often less maintenance, easier to use for the average homeowner, and often more compatible with the needs of modern electricity. Circuit breakers work in one of two ways: the first is by use of an electromagnet and the second is by the use of a bi-metal strip. Once the flowing current reaches any unsafe level, the electromagnetic force becomes strong enough to throw a metal lever in the inner switch mechanism, breaking the current. In the second option, the bi-metal strip can bend, throwing the switch and breaking the connection.

            The biggest difference between circuit breakers and fuses is that breakers can be reset after being tripped and therefore used again and again—this is due to the internal switch mechanism. For this reason, circuit breakers must also have external access which can affect the design of your circuit itself. Circuit breakers can be more expensive to install, replace, or repair but they are the most common form of overload protection found in today’s homes; largely due to their ability to be reset and produce only temporary breaks in flow of electricity.

            In Electrical Applications, circuit breakers are typically the preferred method of circuit protection; this being due to electrical circuits usually being more durable and handling a slower response time before damage will occur. Due to the nature of the bimetal design, some circuit breakers may need to have up to 200% load to trip within 5 seconds. The higher the load; the faster the breaker will trip. Unfortunately on sensitive circuits this will usually result in damage to the circuit itself.

         Fuses and circuit breakers are not interchangeable in every electronic situation; for example, fuses should not be used in situations that require a GFCI. Before deciding which one suits your device or preferences, it’s important to know how many amps your circuit will require. If a fuse or circuit breaker reads a higher than required amp rating, you are allowing the electricity to damage your circuit before tripping the fuse or breaker and therefore defeating the purpose of what they were put there to do. It is not recommended to exceed the number of amps a piece of equipment is asking for. Most electronics will tell you the amps required close to or around where the fuse or circuit breaker is fitted for. If you can’t find it, you’ll find it on the blown fuse or circuit breaker itself.

To Summarize:

Fuse Pros:

            More accurate protection (main purpose of the fuse)

            Prioritizes protection over convenience

Fuse Cons:

            More expensive on circuits prone to overloading and/or tripping

            May require soldering to replace

Circuit Breaker Pros:

            Resettable; therefore reusable

            Less expensive on circuits prone to tripping

Circuit Breaker Cons:

            Slower response time can result in damage

            Higher initial cost

            Sacrifices protection for convenience