Isolator vs MCB: Understanding the Key Differences

Isolators and miniature circuit breakers are widely used in electrical installations. But they have different functions. Below you can see the main differences between them.

Differences Between Isolator and MCB

Isolator and MCB have the following differences.

1. Definition

The isolator is an isolation device used to disconnect the load from the main supply. MCB is a protection device used to protect electrical lines from the negative effects of excessive currents.

MCB trips the circuit but open contact of MCB cannot be visible from outside. (Handle may be broken) That is why it is recommended not to touch any electrical circuit just by switching off the MCB. For better safety, you need an isolator. The isolator is a mechanical switch that isolates a part of the circuit from the system for safe maintenance work. Isolators are used in electrical installation to make, carry and break circuit current.

2. Protection and isolation

The main difference between an isolator and MCB is the protection function. The isolator does not have any protection function. It is used as an isolating switch for an electrical circuit. MCB (Miniature circuit breaker) has overload and short circuit protection functions. It is also capable of isolation.

3. Number of poles

Isolators have 1, 2, 3, and 4 pole versions. MCBs have 1, 2, 3, 4, 1+N, and 3+N pole versions.

4. Maintenance

MCB trips the circuit but open contact of MCB cannot be visible from outside. (Handle may be broken) That is why it is recommended not to touch any electrical circuit just by switching off the MCB. For better safety, you need an isolator. The isolator is a mechanical switch that isolates a part of the circuit from the system for safe maintenance work. Isolators are used in electrical installation to make, carry and break circuit current.

5. Prices and market share

Prices of isolators are cheaper than MCBs but the market share of miniature circuit breakers is larger than isolators.

6. Accessory options

The accessory options of an MCB are wider than isolators.

7. Location in the circuit

Isolators are commonly used as the main switch in a house. Isolators are designed to provide switching under load (even inductive) in household, commercial and industrial applications. Their main function is to allow maintenance of the electric system in safe conditions. They also grant the complete insulation of the downstream circuits. Isolators require upstream protection against short circuits and overloads.

8. Rated current

The Rated current of isolators is from 16A to 125A. The Rated current of MCBs is from 0,5A to 125 A.

9. Circuit symbol

Circuit symbols of isolator and MCB are different. You can see them below.

10. Short circuit withstanding capacity

Isolators have high short-circuit withstanding capacity compared to MCBs.