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HomeElectrical3 Pole Circuit Breaker Wiring Diagram | MCB Connection

3 Pole Circuit Breaker Wiring Diagram | MCB Connection

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As you are aware, there are various types of 3 pole circuit breaker wiring diagram. One well-known type of 3 pole circuit breaker wiring diagram is the molded case circuit breaker or mccb. In this post, you will learn about mccb wiring and initiation. I’m going to share two mccb wiring diagrams with you in this post; one is for a three-pole mccb circuit breaker, and the other is for a four-pole circuit breaker.

We can control a three-phase electrical system with a three-pole circuit breaker, and a four-pole system with a three-phase, four-wiring system. 

People who read this article also read: Can a Light work without a Neutral? Do lights need a neutral?

How to wire Three Pole and 4 Pole MCCB circuit breakers

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The wiring for both the mccb and the mcb circuit breaker is identical and incredibly straightforward. Still, the difference between the two is that the mcb (miniature CB) can handle loads of up to 100 amps while the mccb has a range of up to 1000 amps.

  • Therefore, we cannot use the MCCB and must install the MCCB if we are connecting a distribution board whose ampere is greater than 100 amperes.
  • The three-pole type of molded case circuit breaker is typically in use to control the three-phase system, and this particular model is in use for that purpose. 
  • Nevertheless, we can use it for any work-related task. This circuit breaker can also come handy if the single-phase load exceeds 100 amps.

I outline the entire procedure for wiring and installing a three-pole molded case circuit breaker in the 3 pole circuit breaker wiring diagram that is provided below.

 3 pole circuit breaker wiring diagram
3 pole circuit breaker wiring diagram

When using a 3 pole circuit breaker wiring to control a three-phase circuit, a three-pole circuit breaker is the default choice. However, if the circuit is a three-phase, four-wire system, a four-pole circuit breaker is necessary. 

The diagram below for 4 pole mccb control illustrates the entire installation and wiring process for a 4 pole molded case CB.

 4 pole circuit breaker wiring diagram
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Additionally, use an MCB in your main distribution board and choose your breakers based on your total load if you’re wiring a multi-story building and installing a three-phase, four-wire system. However, I’ll be writing a post about wiring installation in multi-story building diagrams soon, along with a guide in which I’ll connect the mccb wiring.

People who read this article also read: What Causes an Intermittent Power Outage and How to Solve It?

Main Service Panel Wiring Installation of Single Phase and Three Phase, 120V and 208V Circuits and Breakers

One of the common voltage levels used in commercial applications in the USA is 208V, which is available in single-phase and three-phase forms. It can be derived from the transformer’s primary and secondary windings configured Wye-Wye (Star to Star), Delta-Wye, or High Leg Delta.

The following different voltage levels are available in this type of setup from the industrial transformers.

  1. Three hot wires plus a ground wire, 208V, three phases
  2. Three wires, 208V single phase, two hot wires, and a ground wire
  3. Three wires, 120V single phase, one hot wire, one neutral wire, and one ground wire

Through insulated wires that pass through the meter box and safety switch, the three-phase power from the secondary of the distribution transformer finally enters the main distribution panel. For additional distribution, each line or hot wire is in connection to a different bus-bar in the panel box. Circuit breakers with three poles, two poles, and single poles can be snapped (i.e., metal tracks firmly hold the CB) over three busbars that draw hot from each busbar.

Inside The Main Breaker Panel | 3 Pole Circuit Breaker Wiring Diagram

Inside the main breaker panel, the available voltage levels for 120V and 208V, 1-Phase & 3-Phase wiring systems are as follows.

The voltage between the three hot wires (hot 1, hot 2, and hot 3) is equal to 208V three-phase.

Voltage = 208V Single Phase between any two hot wires.

Any hot wire and neutral are in connection at a voltage of 120V single phase.

Nearly every panel box made for Wye and Delta by various manufacturers has the same features, including hot busbars for three pole breakers and separate busbars for Neutral and Ground. Remember that all 208V-120V panels, especially those with the Wye configuration, have a neutral wire unless a particular type of three-phase motor (like a wastewater pump) is used or if a 120V single-phase system is being used and the neutral wire is not required.

Additionally, neutral is not in requirement in all situations involving delta connections. Other than this, whether a neutral wire is a requirement for wiring or not. The ground is also a requirement in almost all configurations (whether Delta or Wye).

3 Phase & 1 Phase Main Panel
3 Phase & 1 Phase Main Panel
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Sarhan Bakshi
Sarhan Bakshi
I am simply a writer out in search of something new. In the process, giving you all a taste of the fruits born from my intellect.
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