How Circuit Breakers Work - Part 1

Circuit breakers, safety switches, RCD’s, circuit interrupters, all among very familiar nomenclature to homeowners around the world. But what exactly are they and what do they do? These days just about every homeowner is probably familiar with two key types of electrical panel components in their home - the fuses and the circuit breaker. And at some point of time you may have found yourself wondering - “I know what the fuse does, but what exactly are circuit breakers and how exactly are they different, what do they even do?” These questions are really important and help you determine exactly what type of breaker you need and help you get on your way to getting the best deal possible when shopping for circuit breakers whether online or at local wholesale retailers.

How Circuit Breakers Cut Electrical Current

As the name very readily implies - the very basic functionality of the circuit breaker device is to simply cut the current going through the circuit as soon as any form of a fault is detected. Now you might be asking yourself, why and how exactly is this useful? To explain it in a super simple way: this helps prevent surge damage to electrical circuits on the network - for example your household appliances. As soon as a fault, commonly a short-circuit and / or a surge scenario, is detected - the circuit breaker interrupts the ongoing electrical current flow within the network. This might sound familiar, don’t fuses do the same exact thing? You’re pretty much on the dot there - very similarly to a fuse and an RCD (Residual Current Device) - many circuit breakers function as an ADS (Automatic Disconnection of Supply) and are a means of removing power from the faulty system before any harm can occur to other components and circuits on the network.

Difference Between Circuit Breakers and Fuses

“Fuses and Circuit Breakers do the same thing at a very basic level, so what is the actual difference?” We get this question quite a lot, and the most basic way to explain the difference is the fact that a fuse is essentially a 1 time use solution, it breaks the current and then needs to be replaced to serve the same function again. On the other hand, a circuit breaker can simply be reset after it is triggered by a fault and the current will flow again. Some of the very early forms of ADS devices appeared around the year 1879, when Thomas Edison patented a power distribution that used very primitive fuses, the purpose of which was to protect the lighting circuit and it’s wiring from accidental overloads and surges. This was shortly followed in 1924 by Hugo Stotz unveiling what is now seen as the early ancestor of the widely used modern thermal-magnetic breaker. This modern breaker is very widely and commonly used to this day in household load centers and across other relatively small networks. Many modern circuit breakers are made in various sizes and intended capacities - ranging from small devices that protect low current circuits (alike to the thermal-magnetic breaker mentioned previously) all the way to large switchgear designed to protect the high voltage circuits that feed your entire city.

We know that when the voltage is given to some circuit, a current is produced in that path. The load to which that current has to be supplied acts as a resistive network and offers some resistance to the current path, to limit the value of the current flowing, so that it can operate safely and do not cause any damage. 

Excessive current only flows in certain conditions, when one or more circuit elements fail to work or work improperly, or any of the wire gets damaged and they short circuit the path of the current such that the power wire gets short-circuited with the neutral wire and hence the value of resistance decreases and a very large value of current flows through the circuit which can cause damaging or heating up of the equipment or one or more of the circuit elements. To prevent this larger amount of current from entering the circuit ahead of its path, circuit breakers are used.


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