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The What, Why and How of Circuit Breakers You Should Know

The What, Why and How of Circuit Breakers You Should Know

The What, Why and How of Circuit Breakers You Should Know

As you may well know, electric circuitry is an essential part of most buildings and homes. This is because they provide us with the electricity that most people have grown accustomed to and dependent on. There is a high chance that electric circuitry can malfunction, which can cause a hazardous situation due to abnormal conditions like overloading and short-circuiting. Therefore, having circuit protection should be a vital part of any circuit infrastructure. 

Circuit breakers are one such component that can aid with circuit protection and safety. According to most electric code legislations in countries, all buildings must have a circuit breaker installed. But what exactly are they? Why are they so useful? How do they work? This article will address all these questions and more.

What is a Circuit Breaker?

A circuit breaker is a built-in circuit safety device that will automatically stop the current from flowing when it detects a fault. In a sense, circuit breakers are switching devices that can detect abnormal and faulty current and interrupt it when necessary. If a circuit breaker is not installed, wiring issues and faults can cause many problems. It is a significant component that the highest safety standard regulations recommend. You will typically find it housed within an electrical panel box.

How does a circuit breaker work?

There are many types of circuit breakers, and each of them works through a different mechanism. Therefore, we will discuss how a simple circuit breaker works to understand its fundamental mechanism. In essence, the simplest circuit protection instrument or component is a fuse.  This device consists of a thin piece of wire or solder housed within a thin protective polymer layer. 

The solder allows the current to flow through it like a standard wire but is designed to melt when the current gets too high. After all, electric current causes a heating effect, and it is directly proportional to the amount of current. This phenomenon happens due to the lower melting point of the solder metal/alloy than copper or aluminum, depending on the type of wire used by a specific power system. Therefore, when the current gets to an abnormal amount, the solder will melt and disintegrate, causing the circuit to open and preventing any further damage from occurring. 

The issue with fuses as a circuit protection device is that it only works once and has to be replaced every time after their application.  A circuit breaker does the same thing, but it comes with the benefit of multiple utilization (But it also has a specific limit that can go up to 1000 cycles depending on the type of circuit breaker).

The basic circuit breaker comprises a simple switch connected to either a bimetallic strip or an electromagnet. 

In the case of the electromagnet, it gets magnetized by the electricity flowing through it. This magnetic property is directly proportional to the current flowing through it. When the current increases to unsafe levels, the electromagnet gets magnetized enough to pull down the metal lever connected to the switch linkage. 

This shuts the entire linkage and disconnects the moving contact and stationary contact, disconnecting or breaking the circuit.

A  design works on the same principle, except that instead of energizing an electromagnet, the high current expands the metal and causes the strip to bend, which disconnects the contact.

You may have noticed the power cut-off or blackouts within your house or building but not affected any other in the vicinity. This is the circuit breaker at work cutting the circuit off for safety.

Why is a circuit breaker necessary?

The primary purpose of circuit breakers is safety. But what kind of situations require a circuit breaker? Typically, there will be two main smaller wires that will be part of the more extensive circuit. These are the hot wire and the neutral wire. These wires will never touch in building wiring, so the current will always go through the application. Additionally, applications are designed to take in low currents for safety reasons, as high currents will cause a higher heating effect. 

However, the hot and neutral wires will come into contact in certain scenarios. An example scenario would be when a fan motor overheats and melts the wires, causing them to meld together. There is minimal resistance in the circuit in such a situation, so a large current flows through the circuit. This current can overheat the wires massively, leading to damage and even a fire. A circuit breaker helps prevent such a situation, making it a necessary safety device.

What are the types of circuit breakers?

There are many circuit breaker types with their own uses and mechanisms. It is helpful to go through all of these to ascertain which one will be suitable for your needs. The types of circuit breakers are:

Standard Circuit Breakers

Standard circuit breakers come in various varieties that keep track of outlets’ electricity cadence, wiring systems, and appliances. This breaker will stop situations like circuit overloads and short circuits by cutting off the current. They are of the following variety:

  • Single-Pole Breakers: These are the most commonly used breakers typically used for low power appliances and standard lighting. They can handle 15-20 amps and supply 120V to a circuit. Additionally, they can protect one energized wire. The WinTrip2 1P breaker series by C&S Electric has a range of single-pole breakers you can use. 
  • Double-Pole Breakers: These protect heavy machinery and large appliances like water heaters and dryers. They can handle between 20-60 amps and supply 240V to a circuit. It can defend two energized wires courtesy of its two single-pole breakers. The 2P circuit breakers of the Wintrip series by C&S Electric are a great example of these.
  • Three-Pole Breakers: Heavy-duty industrial motors often require these as they connect to three different conductors. These breakers work much like single-pole breakers, and the only difference is the higher number of conductors. This breaker trips whenever an electric surge is detected across any of the conductors. The 3P circuit breakers of the Wintrip2 Series by C&S Electric are some useful examples.
  • Four-Pole Breakers: These breakers come into types: TPN, which consists of a triple pole breaker with a neutral pole, or 4P with four poles. These breaks are helpful for multiple incoming power stations, such as in the event of a power failure. We have a range of 4P circuit breakers part of the Wintrip Series by C&S Electric.

GFCI Circuit Breakers

Ground Fault Circuit Interrupter circuit breakers stop power to circuits when surges occur. Additionally, they can also come into effect when a line-to-ground fault occurs, which is when unwanted paths form between a current and a grounded element. These breakers stand out because they are designed to protect people rather than prevent damage to a building. It constantly monitors the current in the hot wire and neutral wire. It is handy for wiring in large damp areas like workshops, basements, outdoor spaces, and kitchens. ELCB circuit breakers, part of the Wintrip series by C&S Electric, are a great example of GFCI circuit breakers. They are available with many pole options according to your needs. 

AFCI Circuit Breakers

Arc Fault Circuit Interrupter circuit breakers protect circuits from catching fire due to electrical arcing. Electrical arcing can occur due to damaged or deteriorated wires and aging cables. AFCI circuit breakers can detect arc faults. These faults are dangerous as they can lead to extreme heating, which can cause fires. AFCI breakers protect against these faults and work in tandem with other circuit breakers to provide a wide range of protection.

What can cause a circuit breaker to trip?

A circuit breaker tripping means that it has broken the circuit. This can be for various reasons that can come under two classifications. These are:

  • An overloaded circuit. This is when too many appliances are under use which can be too much for the circuits to handle. Therefore, unplugging unnecessary appliances is the way to avoid such a situation.
  • A short circuit. This is when appliances have bad or damaged wiring resulting in electric surges. It is good to inspect the appliances for damage and fix or replace them to avoid such a scenario.

How to reset a tripped circuit breaker?

You can reset a tripped circuit breaker in the following ways:

  • Turning off and disconnecting all the appliances and lights connected to the circuit part of the breaker. A sudden surge of power after turning on the breaker can damage them.
  • Locating the switch which is in an OFF position. It would be best to press down on the switch in the OFF position to ensure it is completely OFF. 
  • Flip the switch from the OFF position to the ON position.
  • If the circuit breaker is repeatedly being tripped, there might be an electrical issue. It is recommended to call in an electrician or expert to check for the problem.

What are circuit breaker trip curves, and why are they so important?

Circuit breaker trip curves, or MCB trip curves, consist of two main sections. These are the short circuit section and the overload section. The short circuit section refers to the instantaneous trip current level of the circuit breaker. Additionally, the overload section refers to the trip time needed for various levels of overload currents that the circuit breaker might experience.

Understanding trip curves is essential as you will want to choose a circuit breaker with the appropriate rating and trip curve. In this way, you will be able to safeguard your circuit from any damages and faults that could occur. If the rating is too high, the circuit breaker will not trip when a fault occurs. Similarly, it will begin to trip if the rating is too low, even if the inrush current is normal. Therefore, it is vital to calculate inrush current and short circuit current as you will choose your circuit breaker and its rating based on these values.

What are the types of trip curves?

Courtesy- www.electricaltechnology.org/

There are 5 main trip curves associated with circuit breakers or MCBs. The trip curve will tell you about the trip current rating of the circuit breaker, which is the minimum current at which it will trip instantaneously. A requirement here is that the trip current must persist for at least 0.1s. We will discuss these trip curve types individually. They are:

Class B Trip Curve

Circuit breakers with class B trip characteristics are suitable for standard cable protection by preventing damage to them. These circuit breakers will trip instantaneously when the current flowing through it is between 3 to 5 times the rated current.

Class C Trip Curve

Circuit breakers with class C trip characteristics are generally suitable for most residential and domestic electronic applications. You can also use them for electromagnetic starting loads with medium starting currents. These circuit breakers will trip instantaneously when the current flowing through them reaches the rated current between 5 to 10 times.

Class D Trip Curve

Circuit breakers with class D trip characteristics do not have many applications outside of industrial uses. They are generally suited for inductive and motor loads with high starting currents like transformers and large battery charging systems. These circuit breakers will trip instantaneously when the current flowing through them reaches between 10 to 20 times the rated current.

Class K Trip Curve

Circuit breakers with class K trip characteristics are suitable for motor applications and inductive loads with high inrush currents. These circuit breakers will trip instantaneously when the current flowing through them reaches the rated current between 8 to 12 times.

Class Z Trip Curve

Circuit breakers with class Z trip characteristics are extremely sensitive to short-circuiting, making them ideal for protecting susceptible devices such as semiconductor devices. These circuit breakers will trip instantaneously when the current flowing through them reaches 2 to 3 times the rated current.


When it comes to electric circuits, protection is necessary to prevent hazardous situations that can happen due to electrical faults. Circuit breakers are a valuable circuit protection component essential for most building circuits. This article has looked at everything you need to know about them. We have also talked about different types of breakers to see which ones will be suitable for you. We hope this article proves helpful and helps keep your homes and buildings safe and secure from electric faults.


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