Full form of RCBO – Residual Current Operated Circuit Breaker with Over Current Protection.

What is RCBO – Definition of RCBO is given below –

Definition –

It’s a single devise which performs the function of MCB (for protection from overloading & short circuit) & RCCB (for protection from earth leakage/unbalance current).

This device has been designed for domestic electrical system which can protect user from electrical shock due to over current (overloading & short circuit) and from earth leakage. Its a compact unit contains both functions of MCB & RCCB.

Selection of RCBO –

• Check RCBO is required for single phase or 3 phase load.
• Check number of poles – DP & 4P where

DP = Double Pole which means phase & neutral wires will be connected,

4P = Fore pole which means 3 phases & a neutral will be connected.

• It should be capable to carry rated current of load&
• Fault current rating (in mA) on which relay should trip/interrupts the faulty circuit.

Ex – 40A DP RCBO with 30mA fault current.

CURRENT RATING OF RCBOs –

30mA DP –

A typical range of single phase RCBO – 6A, 10A, 16A, 20A, 25A, 32A, 40A, 63A.

100mA DP –

A typical range of single phase RCBO – 6A, 10A, 16A, 20A, 25A, 32A, 40A, 63A.

300mA DP –

A typical range of single phase RCBO – 16A, 25A, 32A, 40A, 63A.

30mA 4P –

A typical range of Three phase RCBO – 6A, 10A, 16A, 20A, 25A, 32A, 40A, 63A.

100mA 4P –

A typical range of Three phase RCBO – 16A, 25A, 32A, 40A, 63A.

300mA 4P –

A typical range of Three phase RCBO – 16A, 25A, 32A, 40A, 63A.

Frequently Asked Questions on RCBO–

Q1) What is RCBO protection?

Ans) RCBO is a combined unit of MCB & RCCB which provides protection against overloading, short circuit & residual current (earth leakage).

Q2) What is the difference between RCCB & RCBO?

Ans) As we know that RCCB provides provide protection against residual current (earth leakage/imbalance current) only while RCBO provide protection against residual current & over current (over loading & short circuit).

Q3) RCCB & RCBO- which one is better?

Ans) Purpose of both RCCB & RCBO is different as we have understood that RCCB provides protection from residual current (earth leakage/imbalance current) while RCBO provide protection from residual current & overcurrent. Therefore, selection of RCCB & RCBO should be carefully.

Q4) What is RCBO in electrical? What is RCBO Circuit breaker? What is RCBO switch? What is the function of RCBO?

Ans) All above terms are same & talking about RCBO which provides protection against residual current &  overcurrent in an electrical system .

Q5) Why my RCBO is tripping?

Ans) The function of RCBO is to provide protection against residual current & over current so following reasons may be there for tripping –

a) earth fault in the equipment or circuit (wiring)

b) imbalance current in all three phases (if three phase RCBO is installed),

c) Over loading of the equipment / circuit

d) Short circuit