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MCB vs RCCB - Know The Difference!

If you are looking to add circuit breakers to your home, you have probably encountered these two acronyms MCB and RCCB. These stand for Miniature Circuit Breaker (MCB) and Residual Current Circuit Breaker (RCCB). Here I will explain the difference between them, with examples for each type of device.

Before understanding the difference, it is necessary to understand the power supply to your home, as well as its consumption.

The components that make up a housing circuit are the wires, switches, fuses, breakers, sockets, and other devices that run on electricity. The main purpose of circuit breakers is to protect against irregular current flow.

Miniature Circuit Breaker (MCB)

These circuit breakers perform the vital role of breaking the circuit to prevent damage from excessive current due to short circuit or overload.

When a short circuit occurs, a large amount of current begins to flow causing the MCB to trip almost immediately. In the event of an overload, it takes a few seconds to trip and interrupt the circuit.

Overloading and short circuits in the power supply can be dangerous for both people and equipment. To minimize these risks, MCBs are installed.

Residual Current Circuit Breaker (RCCB)

It is a current-operated safety device that breaks the circuit when current leaks are detected, thus ensuring protection against electric shock.

Current leakages mainly happen when the current flowing in the circuit gets branched by a person who has direct or indirect contact with the current-carrying conductor. An MCB cannot detect these irregularities, whereas it can be easily detected by the RCCB.

A major advantage of RCCB is that it can control unbalanced electric current almost instantaneously, taking only 20 milliseconds to trip.

The main difference between MCB and RCCB is that MCB is used to prevent short circuits & overload protection and RCCB prevents earth leakage.

Basic Difference

MCB

RCCB

Cost

Less

More

Manual ON/OFF

Yes

Yes

Earth Fault Protection

No

Yes

Overload Protection

Yes

No

Short Circuit Protection

Yes

No

Sensitivity

Relatively Less

Relatively More

No. Of Poles Available

1,2,3,4

2 for Single Phase

4 for Three Phase

Application

Fuse Alternative, Protective Circuit, Local Control Switch

Direct & Indirect Contact Protection, Prevent Electrical Failures

Test Operation

Cannot Be Checked

Working Condition Can Be Checked Using ‘T’ Button

WHEN MCB IS CONNECTED BEFORE RCCB:

If the short-circuit fault occurs on the load side, MCB detects the short-circuit and gets tripped. When the fault occurs between the MCB and RCCB, it also detects the fault, trips, and breaks the circuit.

WHEN MCB IS CONNECTED AFTER RCCB:

If a fault occurs on the load side, mcb can detect and trip the circuit. However, if the error occurs between the rccb and the mcb, the mcb will not recognize it, nor will the rccb be able to detect such errors. The fault remains in the circuit. It is therefore always recommended as a best practice to connect mcb before rccb.

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