Isolator vs MCB: Understanding the Key Differences

If you’re working with electrical circuits, it’s essential to understand the differences between isolators and MCBs (miniature circuit breakers). While both devices serve critical functions, there are significant distinctions between the two. In this article, we will examine the differences between isolators and MCBs, including their definitions, protection and isolation capabilities, number of poles, maintenance requirements, prices, market share, accessory options, location in the circuit, rated current, circuit symbol and short circuit withstanding capacity.

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. It’s important to choose the correct pole version for the application to ensure proper circuit protection and safety.

4. Maintenance

Prices of isolators are cheaper than MCBs but the market share of miniature circuit breakers is larger than isolators. While the prices of isolators may be cheaper, factors such as safety, functionality, code requirements, and brand recognition could explain the larger market share of MCBs.

6. Accessory options

The accessory options of an MCB are wider than isolators. Because MCBs are designed to provide more functionality and protection 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.

It’s important to select the appropriate isolator or MCB based on the specific requirements of the electrical circuit and equipment being protected. Factors such as the maximum current draw, the type of equipment being used, and the voltage rating of the circuit must all be considered when selecting the appropriate device.