What about fuses verses breakers? Each of these serve a purpose in providing overcurrent protection in electrical circuits. They both have pros and cons.

Circuit breakers are reusable whenever an electrical circuit experiences an overcurrent in the circuit, which then trips the breaker. The breaker is simply reset with its switch handle. This, at first appearance, can effectively reduce the cost of overcurrent protection especially if you experience high incidents of overcurrents. However, there are still some drawbacks with breakers when comparing them to fuses.

For one, circuit breakers have mechanical parts, which creates an inherent increase in required maintenance for the breakers.

Breakers need to be exercised periodically by switching them. This essentially interrupts active loads. Fuses do not have any moving parts. Therefore, eliminating this kind of maintenance. The cost for maintenance for circuit breakers needs to be factored in when considering the use of fuses verses circuit breakers. Safety may be compromised if breakers are not maintained properly or replaced when the integrity of the breaker has been degraded. Also the associated circuit breaker equipment needs to be maintained, such as the breaker and wire termination points, and ensuring proper mounting.

Fuse associated equipment also needs to be maintained with its terminations, clips, and disconnects; but again, there are no moving parts.

Fuse links are not reusable. Once they experience an overcurrent such as short-circuit or overload beyond its rated limits, it opens (blows) by the fuse link melting. You have to replace the fuse with a new fuse or fuse link. Ironically, here is where using fuses shine. Where circuit breakers can degrade by their movable parts, this can lead to a breaker’s calibrated settings being affected, this does not happen to a fuse.

This is important for various types of circuitry and loads to be protected. If the calibration of the circuit breaker is adversely affected and does not open when called upon based on its current rating, this could possibly damage the conductors or the loads being protected. This also could pose a fire hazard. Using fuses eliminates this potential problem.

Other circuit breaker failure considerations are a burned out trip coil or the trip mechanism becoming immovable because of corroding buildup, dirt, and/or dried out lubricant. Certain breakers with electronic components can also fail when the electronic component fails. Again, these problems can result in a fire hazard to life and property.

Whenever a fuse is called upon to perform its action of protection by the fuse link opening, a new fuse is installed providing optimum calibration settings. Because of this, using fuses provides reliability and confidence of performance beyond that of circuit breakers.

Because of the difference of electrical utilization of fixtures, equipment, and machinery, fuses are manufactured in basically two time characteristic types; fast-acting and time-delay. With little or no inductive loads, such as motors and transformers, fast-acting fuses are better suited for incandescent lighting and general purpose use. Fast-acting fuses provide protection from short circuit and sustained overloads. Increasing the fast-acting fuse rating 200 to 300 percent of load current to compenstate for nusiance opening, because of in-rush currents from inductive loads, results in ineffective overload protection. A time-delay fuse would be better suited in this case.

High speed or very fast-acting fuses are used to protect solid state devices such as semiconductors or rectifiers.

Time-delay fuses are better suited for inductive loads, such as motors and transformers where high initial in-rush currents are experienced on startup. These fuses help to prevent unnecessary opening resulting in unproductive downtime. This can be a nuisance especially from a manufacturing standpoint with downtime and maintenance personnel costs, not to mention increased fuse replacement costs. Time-delay fuses offer the protection from short circuit and sustained overloads with the added benefit from opening because of harmless surge currents. Time-delay fuses also allow for downsizing the rating of fuses on most motor loads closer to 125 to 150 percent of motor full load current. This reduced fuse rating could possibly reduce fuse size and disconnect which could also reduce cost.

A fuse is simply a carrier of electrical current which has a special function to interrupt the passage of current flow whenever there is an overcurrent in its path. An overcurrent could be a sustained overload, fault, or short circuit in the wiring, equipment, or electrical devices. These materials have an electrical rating and an overcurrent occurs when the current exceeds that rating. The link inside the fuse housing is made and designed of materials which are calibrated to open the circuit by melting whenever there is an overcurrent beyond its calibration settings to safely carry electrical current. Once the fuse link has opened the fuse has done its job in circuit protection. This fuse is commonly referred to as “blown” and will need to be replaced once the condition that caused the fuse to blow has been remedied or repaired.

Welcome to my first post. Fuses play such a very important role in our lives it goes pretty much undetected by the normal person. However, its importance is significant in the protection of property and persons. When electrical current gets out of hand, the fuse puts a stop to it, thus protecting against potential fire, damage to property, and even injury or death to persons. This weblog will be devoted to information about electrical fuses, associated equipment, and use.