Huge power overloads or short circuit can potentially raze electrical circuits and appliances, or cause a fire. Therefore, preventive measures needs to taken to avoid those actions. A fuse and circuit breaker are used for these preventive measures. They do this by interrupting the flow of current in the circuit. How they interrupt the flow of current is very different.
A fuse consists of low resistance wire enclosed in a non-combustible material like glass or ceramic. It is made up of a piece of metal (alloy) that melts when overheated. The fuse will break or open the circuit if a fault in an appliance causes too much current flow. This action by the fuse protects the appliance from damage. There are numerous types of fuses in the market but the purpose of all these fuses are the same.
Fuses in plugs are made in standard ratings. The most common are the 3A, 5A, 13A and 15A. A fuse is usually rated at a slightly higher current than a device needs. For example, if a device works at 1A, a 3A fuse is used and if a device works at 13A, a 13A fuse is used. A Fuse is usually connected in series to the device that is being protected.
How A Fuse Works
In a home, the fuse is naturally plugged into a central fuse box where all the building’s wiring passes through. When the electrical energy is flowing normally, the fuse allows the power to pass uninterrupted across its wire, between circuits. If an overload or short circuit occurs, the metal melts, stopping the flow of electrical energy.
This action by the fuse relatively takes very little time to occur depending on the type of fuse used, thereby any power surge is quickly stopped. When a fuse is blown, however, it must be discarded and replaced with a new one which has the same rating with the blown one. If a fuse is not replaced with the same rating as the blown one, it will definitely affect the working of a circuit. For example, if a blown fuse is rated 5A and is being replaced with 3A fuse. The device will function impulsively when connected to source of power but if the blown fuse is replaced with 13A fuse, the device will be vulnerable to damage because the 13A fuse will allow current greater than 5A to flow into the device.
A circuit breaker does the same job as a fuse but it works in a different way. It has an inner switch mechanism that is tripped by an unsafe flow of electricity. It is made up of a spring loaded with soft iron bolt. Circuit breakers are most commonly found in modern homes, many updated homes have circuit breaker panels instead of fuse boxes. Circuit breakers are usually found in a cabinet of individual switches known as breaker box. The easy switch action of a circuit breaker also makes it easy to switch off an individual circuit in a house if it’s required to work on the wiring in that location. Just like fuse, there are different types of circuit breakers.
How a circuit breaker works
A circuit breaker works in one of two ways, with an electromagnet (or solenoid) or a bi-metal strip. It also works with a spring loaded push switch which is held in a closed position by a spring loaded soft iron bolt. In both case, the fundamental design is the same; when it is turned on, the breaker allows electrical current to flow through the solenoid or strip.
When the current increases beyond a set limit, the magnetic force of the solenoid becomes so strong that a metal lever within the switch mechanism is thrown, and the current is broken.
Advantages and Disadvantages
The fuse and circuit breaker both have advantages and disadvantages, each of which can depend on the situation in which they are used. Fuses are cheap and readily available. They also respond very quickly to overloading or electrical surge, which means that they can offer more protection to sensitive electronic devices.
Fuses must always be replaced once they are blown, which can be challenging, if the correct replacement is not immediately available.
Circuit breakers have many advantages, not the least of which is how easily and quickly they can be reset when it trips off. It can be reset by simply turning the tripped circuit breaker off and back on.
Also a circuit breaker normally does not react as quickly as a fuse to electrical surges, meaning that it is possible that electronics connected to the circuit could be damaged by the unsafe current. Furthermore it is more sensitive to vibration and movement, which can result to the tripping of the switch for reasons not related to an electrical overload or short circuit.
Circuit breakers are more common than fuses these days, but that doesn’t automatically mean that your fuse box needs to be replaced if you have it other than a breaker panel.