[Proper] MCCB Connection Diagram and Wiring

In this article, you are going to learn the proper connection of MCCB with the wiring diagram. MCCB means Moulded Case Circuit Breaker. MCCB is an electrical Protective Device. The main function of an MCCB is to protect the electrical circuit or electrical equipment from two major electrical faults - 1. Overcurrent fault 2. Short Circuit Fault. MCCB provides almost the same function as an MCB just the difference is MCCB is designed for high to extremely high currents. Modern MCCB also provides extra features like - adjustable tripping current function, phase failure, etc.

MCCBs are mostly used for industrial high current applications such as Motor Circuit, as an incoming breakers in LT Panels, CNC Machines, Elevators, Electric Cranes, etc. MCCBs are rarely used for a particular electrical load. They are mostly used for the main incoming of large circuits, wirings, and multiple loads.

Three Pole MCCB Wiring Connection

As you see in the above figure, the MCCB has a total of 6 terminals - three input terminals and three output terminals. Generally, most of the MCCB is designed to connect the input supply at the bottom side and output from the top side. 

So, you can see all three phases(R, Y, B) of the input power supply are connected at the bottom side of the MCCB, and outgoing are connected to the top side of the MCCB. Outgoings are connected to the Busbar. A busbar is used when multiple loads are connected to the same circuit. In the above diagram, only one load is shown.

How to do Wiring of MCCB?

1. First, select the MCCB with the proper rating according to the load.

2.  Connect all the phases of the power supply at the input side. There should be no loose connection.

3. Connect all the phases of the load at the output side. There also should be no loose connection.

Four Pole MCCB Connection Diagram

Here you can see the connection diagram of the four-pole MCCB in the above figure. The four-pole MCCB connection is almost the same as the three-pole MCCB just the difference the neutral should be connected at the left side as shown in the above wiring diagram.

Four poles MCCB has a total of eight(8) terminals - four input terminals and four output terminals. Here also same, the input should be connected at the bottom side and the output should be connected at the top side.

Read Also: 

• Working and connection diagram of Single Phasing Preventer.
• Proper RCCB connection Diagram with MCB.
• Motor Control Circuit Forward Reverse | Wiring and Connection
• ON, OFF, TRIP Indication Lamp Wiring Connection
• Contactor holding circuit with Push Button Switch

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