Isolators Vs Circuit Breakers: All You Need to Know 

Home Isolators Vs Circuit Breakers: All You Need to Know 

The mechanism of the electrical devices might often be complicated. It is significant to understand that each electrical equipment parts have a specific function to perform. In this article, we would consider the difference between isolator and circuit breaker. While the isolators are meant to disconnect in case of an offload situation, the circuit breaker is meant for disconnection during the on-load situation. Many might get confused between them as they are protecting devices, but their purpose is quite different. 

What Is An Isolator?

A DC isolator
Source: Beny

Isolators can be considered as the mechanical device utilized for the disconnection of any electrical equipment or the circuit from the main supply. Being an offload isolation device it only functions while the current passing through the system is zero. The presence of an isolator ensures maximum safety during maintenance. Furthermore, the isolator has a lesser breaking capacity, and they also lack the built-in arc suppressing system. 

This device disconnects a part of the electrical device from the main current. Furthermore, the isolator prevents any kind of short circuits or faults and safeguards the circuit hardware from any damage. It is the most preferred device for technicians, especially for safety purposes. 

What Is A Circuit Breaker?

Mini circuit breaker
Source: Beny

A circuit breaker is the most essential security device of the electrical system. Considered a protecting device, it protects the electrical equipment against circuit overload or any kind of faults in the circuit. These devices instantly identify the fault and prevent or break the electricity flow to the circuit. The increase in the intensity of the fault increases the power interruption. The built-in arc quenching system enables its usage in case of any circuit faults. 

Furthermore, the built-in extinguishing system within the circuit breaker enables its high withstanding capacity and helps in creating interruptions during heavy loads and faults. Therefore they are most commonly found in heavy load devices, for instance, transformers. 

Similarities Between Isolator And Circuit Breaker 

Circuit breaker 2
Source: Pinterest

Although, isolators and circuit breakers are different from each other there are certain similarities between them as well. Both the devices can operate during the offload conditions. Furthermore, they prevent the power flow in case of any fault in the electrical system. The most significant factor is that isolators and circuit breakers are the protecting devices. 

Isolators and circuit breakers are used when there are dangerous voltages present, for safety and protection. In these situations, it is crucial that the consistency of the electrical system should never be compromised. For example, let’s say there was an electrical fire or another emergency, like dangerous fumes entering the ventilation system or gas escaping into an area, this would require isolator and circuit breakers to protect the ventilation system.

An isolator switch or a circuit breaker for hazardous settings can also stop the cross-contamination of dangerous voltages within a system if there is a failure of any kind. Even though the operating systems of both devices are different, their functionalities in protecting the electrical system remain the same. The isolator switch and circuit breaker’s main similarity is that both of them cut off any direct current between the input of the electrical system and its output. 

Differences Between Isolator And Circuit Breaker 

The isolators and circuit breakers are different from each other based on different factors such as working, type of device, functions, operations, power routes, trap charges, and many more. Let’s discuss these factors in detail. Some of the basic differences between the circuit breakers and isolators include

  • The isolators can neither break load nor create any faults, whereas the circuit breakers have been designed for it. 
  • The operations of the isolators always take place after the circuit breaker, therefore the circuit breaker should always be operated before it. 


The isolator is an isolation device that has a mechanical switch, without an arc suppression system. Contrary to this the circuit breaker consists of the electromechanical switch along with a relay and an arc suppressing system. 

Working Principle 

The working principle of the electrical isolator is quite simple. It can be operated in several ways from manual, and semi-automatic to fully automatic. The isolator switches can be opened and closed as per the necessities. In some cases, they are also fixed permanently. 

The circuit breakers have internally fixed as well as moving metallic contacts along with the coils. When the electrical equipment is functioning normally, the circuit is closed, hence the contacts are joined together. In case of an overload situation, the circuit is opened and the moving contacts are separated preventing the power flow. 

Type of Load Devices 

The operation of an isolator is a “no load” device since it can only operate when the power flow is zero. The circuit breaker, on the other hand, is an “on-load. device since it functions smoothly while the power is flowing through the entire system. 


An isolator function when there is no power flow within the circuit. Its significant function is to specifically isolates the part of the electrical equipment or system with faulty conditions and makes the entire electrical device safe for repair. Its main utilization is at the time of inspection and maintenance purposes. Furthermore, most of the isolators require manual switching and are not designed for automatic functionalities. 

The circuit breaker, on the other hand, works automatically. Thus, in case of any faults in the electrical system, it instantly cuts off the power supply throughout the system. It can be operated automatically as well as manually, depending on the type purchased. 


The isolator can only begin working once the power supply is completely zero. The isolator should only be opened once the circuit breaker has opened. It can be easily operated manually and would not be less expensive. While using it manually one can use up to 145kV, in the case of high voltage systems it can utilize around 245 kV.

The circuit breaker consists of two significant parts fixed as well as moving arms. When the circuit breaker is switched on both the contacts are held close to each other as there is pressure being applied to them. Furthermore, these circuit breakers can also be utilized for storing the potential energy which is released during the operation. This release of the potential energy enhances the speed of the moving contacts. 

Types Of Functionality Devices 

There are mainly three different types of isolators which include: Double break type isolator, Single break type isolator, and pantograph type isolator. Each of them has a specific purpose and characteristic feature. 

Double Breaker type isolator- this isolator mainly consists of three loads of post insulators. The post insulator placed in the center is rotational as well as movable. There is a tubular male contact meant for connections and disconnections at the ends of the circuit. These are designed in a way such that when the male contact rotates in an opposite direction the female contact isolates or gets disconnected. 

Single break type isolator- in this isolator the arm contact is divided into two main parts. The first arm contains the male contact whereas the second arm consists of the female contact. These are contacts are fixed on the post insulator, therefore when it rotates, there is a shift in the arm contacts. 

Pantograph type isolator- this type of isolator does not require much space and plays a major role in the installation of switchgear. It further consists of the operating insulator as well as the post insulator. 

There are several types of circuit breakers available, each having a different function and operation. Some of the important types of circuit breakers include: Standard Circuit breakers, GFCI, and AFCI

Standard: This type of circuit breaker is responsible for monitoring the amp capacity of the electrical equipment they operate. To know the load capacity of the standard circuit breaker check its amperage and wattage. 

GFCI: Ground Fault Circuit Interrupter is responsible for cutting off the power throughout the entire circuit. There is a kind of trip in the circuit in case of an overload such as a short circuit or any other circuit fault. This type of circuit is a favorable choice for ground fault protection. 

AFCI: Arc Fault Circuit Interrupter protects the electrical system against undesired electrical discharge in any of the wiring that could possibly cause a fire. 

Installation Procedure

The isolator is mainly installed at the two ends of the circuit breakers. A distribution network technician is not required to connect or disconnect any electricity supply when an isolator switch is installed between the meter and fuse board. This ensures the circuit is safe and de-energized so that maintenance work can be done. On the other hand, circuit breakers are installed in the circuit itself to interrupt the circuit in case of an emergency. 

Thermal Capacity 

The isolator does not require any kind of insulating medium or insulation for its operation. Contrary to this the circuit breakers utilize different mediums such as air, vacuum, gas, or oil for better insulation. 

Kinds of Contact 

The isolators consist of the main as well as the moving contacts. The status of these arms or contacts can be seen as they play a significant role in the maintenance. The circuit breakers, on the other hand, consist of the arcing as well as the main arms, however, they cannot be viewed.

Trap Charges 

The trap charges can be easily eliminated in the isolators. However, in the case of the circuit breakers, the trap charges can be disabled or removed. 

Earth Switch

An earthing switch is a mechanical tool used to safeguard circuit components. Under unusual circumstances like short circuits, it can maintain currents for a set amount of time. It does not carry any current in a typical circuit. It is activated only when there is an aberrant state.

An isolator can consist of either a single switch or a double switch. The circuit breaker does not consist of any kind of earth switch. 


There are no interruptions in the power supply, as the isolator is only responsible for the isolation of the specific parts for maintenance or repair purposes. The circuit breakers interrupt the current flow in case of any faults or undesired conditions in the electrical system. 

Current Flow Operation 

It is forbidden to open the isolator during the current flow. It is always advisable to switch off the circuit and stop the current flow. The circuit breaker can be opened during the current flow. However, it can work in both states either on or off.


One of the main purposes of isolators is maintenance. While the maintenance, the isolator is switched off and the system is repaired accordingly to ensure smooth functioning of the system. The maintenance is done frequently for the isolators. The circuit breakers do not require frequent maintenance and are better done by a professional.


The isolators are mainly utilized in the industrial sectors, contrary to this the circuit breakers can be used in both industrial as well as domestic sectors. 

Withstanding Capacity 

Being an off-loading device the isolator has a low withstanding capacity and can easily catch fire if it is utilized in extreme on-load conditions. The circuit breakers are on-load devices and have a higher withstanding capacity and can regulate high currents. 


Just like other characteristics of the isolators and circuit breakers, their symbols differ as well. A horizontal line is the representative symbol of the isolator. The circuit breaker is a combination of different symbols of its parts. 


The isolator utilizes the atmospheric air as the medium, whereas the circuit breakers utilize different mediums such as atmospheric air, vacuum, SF6 gas, etc. 


Isolators are cost-effective and can be purchased for a low amount of around $20. However, the circuit breaker is expensive and requires a greater investment of around $100. 

Over Voltage Switching 

The isolators do not undergo any increase in the overvoltage on switching on. However, there might be an increase in the overvoltage of switching on the circuit breakers. 

Safety Measures

When it comes to safety, isolators are considered to be safer since they require the complete prevention of current flow through the system for maintenance purposes. Before every operation, the technician turns off the power supply. Contrary to this circuit breakers are not considered a safer option and should only be handled by a skilled and trained technician. 


The number of poles in the isolators is higher in comparison to the circuit breakers.


Both isolators as well circuit breakers are significant parts of the electrical system. They ensure that the electrical appliance is safe from any kind of damage or faults. They also play a major role in the regulation of faulty conditions. 

As far as the functions of these two mechanical devices are concerned, both are similar, but there lies a major difference in terms of their working principles, operations, functions, parts, and many more. Thus, it is important to know about each of them in a detailed manner to prevent any kind of confusion. 

You can refer to Beny to get a detailed insight and the wide range of electrical components for your electronic equipment. 

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