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Circuit Breaker vs. Isolator: What's the Difference?

Edited by Janet White || By Harlon Moss || Updated on October 19, 2023
Circuit breaker interrupts current flow during faults, whereas isolator disconnects a part of the circuit manually.

Key Differences

A circuit breaker is an automatic device that stops the flow of current in an electrical circuit when a fault or overload is detected. On the other hand, an isolator is a manual device used to ensure that an electrical circuit is completely de-energized for service or maintenance.
While a circuit breaker's primary function is to protect an electrical circuit by stopping the flow of current, the isolator's primary purpose is to provide safety for the maintenance personnel.
Both are essential for the safety and efficiency of electrical systems, but they serve different roles.
The circuit breaker acts as a protective shield against electrical faults, while the isolator ensures that the circuit is completely off when required.

Comparison Chart


Protects against overloads and short circuits.
Disconnects a circuit for safety during maintenance.




Mostly during fault conditions.
During maintenance or isolation of circuits.


Typically in ON position unless a fault is detected.
Normally in ON position, switched OFF for isolation.


Protective device.
Switching device.

Circuit Breaker and Isolator Definitions

Circuit Breaker

A device that interrupts the flow of electricity when an overload or short circuit occurs.
When the microwave and toaster were used simultaneously, the circuit breaker tripped to prevent a potential fire.


A device used to disconnect a portion of an electrical circuit for safety purposes.
Before working on the electrical panel, the technician engaged the isolator.

Circuit Breaker

A switch that terminates power flow when excessive current is detected.
The circuit breaker in our basement trips whenever we plug in too many appliances.


A manual switch that ensures an electrical system is de-energized during maintenance.
Using the isolator, the repairman ensured no current flowed through the wires.

Circuit Breaker

An electrical device that can be reset after interrupting current flow during a fault.
The technician recommended checking the circuit breaker first when the lights went out.


A tool used to segregate a section of an electrical system from the main supply.
For safety, the isolator was turned off before the maintenance began.

Circuit Breaker

An automatic safety switch that stops the flow of electricity in a circuit.
After the lightning storm, we had to reset the circuit breaker several times.


A device ensuring complete de-energization of a circuit for operational safety.
Before replacing the faulty component, the technician checked if the isolator was engaged.

Circuit Breaker

A protective mechanism that safeguards electrical systems from damage.
The factory's machinery is safeguarded by several circuit breakers to ensure safety.


A switch that physically separates a circuit from its power source.
The factory had several isolators to safely handle different sections of the machinery.


To cause to be alone or apart, as in being inaccessible or unable to move about
The police isolated the area until more help could arrive.


To place in quarantine.


Is the isolator always manually operated?

Yes, isolators are typically manual devices meant for safely disconnecting a circuit.

What is the main purpose of a circuit breaker?

The main purpose of a circuit breaker is to protect electrical circuits from overloads and short circuits.

Do circuit breakers wear out over time?

Yes, repeated tripping and aging can wear out a circuit breaker, necessitating replacement.

Can circuit breakers prevent all electrical accidents?

While they significantly enhance safety, they can't prevent all accidents, especially if used improperly or if they malfunction.

Do you need to switch off the circuit breaker before using an isolator?

Yes, for safety, the circuit breaker should be off before operating an isolator.

Is it necessary to have both a circuit breaker and an isolator in a circuit?

While not always mandatory, having both provides enhanced safety for both the electrical system and maintenance personnel.

How does an isolator differ from a circuit breaker?

An isolator is a manual switch used for disconnecting a circuit, while a circuit breaker is an automatic device that interrupts current flow during faults.

Why is a circuit breaker considered an automatic device?

Because it automatically trips or interrupts current flow when a fault or overload is detected.

When is an isolator typically used?

An isolator is used during maintenance or when a section of the circuit needs to be isolated for safety.

How often should circuit breakers be checked?

Regular inspections are recommended, typically annually, to ensure they are functioning properly.

Are isolators used in residential setups?

While more common in industrial settings, isolators can be used in residential setups, especially in specialized equipment.

What happens if a circuit breaker fails to trip during a fault?

If it fails to trip, it could lead to equipment damage, fire, or other safety hazards.

How does an isolator ensure safety?

By physically disconnecting a portion of a circuit, it ensures no current flows, making it safe for maintenance.

Should an isolator be used frequently?

An isolator should be used as needed, primarily during maintenance or when isolating a section of a circuit for safety reasons.

Can a circuit breaker act as an isolator?

While a circuit breaker can disconnect a circuit, it's primarily for protection against faults, not for safe maintenance like an isolator.

Can a circuit breaker be manually reset?

Yes, once a circuit breaker trips, it can be manually reset after addressing the cause of the trip.

How do you determine the right size of a circuit breaker for a circuit?

The size is determined based on the maximum current load of the circuit and additional safety margins.

Is there any risk in manually operating an isolator?

If operated without first turning off the circuit breaker, there could be arcing or other hazards. Always follow safety procedures.

Can you provide an example of when an isolator might be used?

Before working on a section of power lines, linemen would use an isolator to ensure that specific section is de-energized.

What's the visual indicator that a circuit breaker has tripped?

Many circuit breakers have a red or different colored indicator that shows when they've tripped.
About Author
Written by
Harlon Moss
Harlon is a seasoned quality moderator and accomplished content writer for Difference Wiki. An alumnus of the prestigious University of California, he earned his degree in Computer Science. Leveraging his academic background, Harlon brings a meticulous and informed perspective to his work, ensuring content accuracy and excellence.
Edited by
Janet White
Janet White has been an esteemed writer and blogger for Difference Wiki. Holding a Master's degree in Science and Medical Journalism from the prestigious Boston University, she has consistently demonstrated her expertise and passion for her field. When she's not immersed in her work, Janet relishes her time exercising, delving into a good book, and cherishing moments with friends and family.

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