## Proper RCCB connection Diagram with MCB.

Today we are going to know "Proper RCCB connection Diagram with MCB". If you do not know the connection of RCCB then this article will be helpful for you. There are many electrical engineering students and many other people who work in electrical wiring have some confusion about the selection of rating of circuit breakers and also the connection of RCCB and MCB. In this article, I have tried to solve these confusions.

### What is MCB?

MCB means Miniature Circuit Breaker. MCB is a protective device that protects the electrical circuit as well as loads from short circuits and overload faults.

### What is RCCB?

RCCB means Residual Current Circuit Breaker. It is also a protective device it breaks the circuit when the leakage current occurs.

### RCCB connection Diagram with MCB:

As RCCB cannot give protection from short circuit and overload faults so generally RCCB is always used with MCB. The Proper RCCB connection Diagram with MCB is given below.

click on the image to enlarge

### Which should be connected first RCCB or MCB?

Many people have this confusion. MCB always should be connected first because if there is any fault occurs between the RCCB and MCB when RCCB is connected first the MCB could not protect so the RCCB and the circuit may be damaged.

### How to Select Rating of RCCB and MCB?

Mainly the RCCB has two current rating

(1) Rated Current like 16A,20A, up to 125A
(2) Rated I∆n Sensitivity like 10mA, 30mA, 100mA

The rated current indicates that the RCCB will be not damaged up to this rating current. For example, a 20A RCCB can withstand 20A current that means when more than 20A current flowing through it it will be damaged.

Now, suppose an RCCB has Rated I∆n Sensitivity 10mA that means when 10mA or more than 10mA leakage current occurs the RCCB will be Trip.

So always select the rated current of the RCCB more than MCB current rating. For example, if you use 20A MCB then you must use the RCCB of more than 20A rated current rating. If you use RCCB of current rating less than MCB current rating then the RCCB will be damaged.