What Is a Resettable Fuse?

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  • Written By: Malcolm Tatum
  • Edited By: Bronwyn Harris
  • Last Modified Date: 30 November 2019
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A resettable fuse is a type of electrical component that is more properly known as a polymeric positive temperature coefficient fuse. The function of this type of fuse is to trip in the event that a flow of current above and beyond the amount that can be managed by the wiring or device is received. This effectively helps to prevent damage to the wiring and any appliances or machinery that may be attached. At the same time, a resettable fuse goes one step beyond other types of fuses, since the component is capable of resetting itself once the overload of power is reversed and the flow of current is restored to normal ranges.

The function of a resettable fuse involves two specific phases. During the first phase, the temperature generated by the flow of current is analyzed to make sure that it is within acceptable range. This is managed courtesy of the polymer coating that is found on the device. Resistive components such as carbon are also present, making it possible to constantly monitor the temperature and flow of current to make sure the flow will not damage wiring or connected devices. Should the temperature exceed acceptable limits, the resettable fuse shuts down the flow into the wiring, preventing any type of overload situation.


The properties of the resettable fuse continue to monitor the temperature and only allow the flow of current to be re-established when the higher level of current has dissipated and levels return to acceptable parameters. Upon detecting this phenomenon, the fuse activates once again and the flow of current to the wiring and on to any devices connected to the wiring is restored. Using a resettable fuse strategy in electrical systems can go a long way toward protecting expensive machinery and other equipment, minimizing the need to replace damaged wiring or machines that have been destroyed due to a power surge. For this reason, fuses of this type are often included in many business settings, including factories and other facilities where heavy equipment is in regular use.

One of the benefits of a resettable fuse is this ability to automatically detect when the power flow is normalized once again and automatically reset. From this perspective, there is one school of thought that holds that a more appropriate popular name for this type of component is the self-resetting fuse, since there is no need for manual intervention to activate the fuse once the crisis has passed. Along with protecting wiring and equipment, the resettable fuse also can save time in terms of restoring the flow of current in the most efficient manner.


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