Difference Between MCB, MCCB, ELCB, RCCB and RCD

The MCB, MCCB, ELCB, RCCB and RCD are more often controversial most of the time to select from and to install in homes, commercials or instead industries too, and the reason is simple as neither the user nor the electrical contractor knows their difference precisely, resulting in investing money in an excellent electrical installation without enjoying it’s right functioning, making user vulnerable to electrical shocks, fire hazards, dark outs, and malfunctioning of electrical gadgets.

Difference Between MCB, MCCB, ELCB, RCCB and RCD

The worst occurs when after installation some incompetent person tries to fix them, with his experience or little knowledge, gathered from here and there without any academic learning of how these gadgets operate, and why they trip and create a nuisance.

The circuit breakers are otherwise designed to break and extinguish the arc safely flowing at the breaker terminals to prevent any sparking at the terminals or fire in the circuit breaker while disconnecting the supply from the live load.

Here, we will discuss them threadbare in the most convenient way to read them and understand their terminology

What are these MCB, MCCB, ELCB, RCCB and RCD called?

All these electrical gadgets belong to electrical circuit breaker category to connect the incoming electrical supply to equipment during regular operation and to immediately provide protection to personnel, equipment and the entire electrical installation from malfunctioning, damage, electrical shock, or even fire by disconnecting the electrical supply from the equipment by triggering the inbuilt protective system in them depending upon the nature of the fault.

Depending upon the cause and the nature of the fault different circuit breakers operate in the installation at different places whether the localized one that is directly connected to the equipment or the one that is connected close to the incoming supply to take care of the entire electrical installation. Here follow their descriptions –

  • MCB – Miniature Circuit Breaker
  • MCCB – Moulded Case Circuit Breaker
  • ELCB – Earth Leakage Circuit Breaker
  • RCCB – Residual Current Circuit Breaker
  • RCD – Residual Current Device

These circuit breakers are installed at different-different places in the electrical installation for specific applications depending upon the type of protection required.

What is Short Circuit?

A short circuit occurs when two or more wires supplying electrical supply to the equipment come in contact with each other making the current flow from the unintended path.

In other words when the phase and neutral wire come in direct contact with each other without any load connected in between them, it leads to short circuit.

During normal operation, the current flows from one wire say ‘Phase’ and returns through the other wire say ‘Neutral’, after supplying the required voltage to the equipment connected in between these two wires.

What is Short Circuit

Why Short Circuit Occurs?

When the two wires Phase and Neutral come in contact somewhere on the way or get shot, the point of contact at the short wire provides a low impedance path to the current resulting in an excessively huge current immediately flowing through the system with a potential to damage the equipment in addition to blazing the electrical system as well as damaging and blazing the equipment.

Therefore, short circuit protection is a must to all electrical gadgets without distinction or segregation. 

How does Short Circuit Protection work?

Short Circuit is immediately realized by a magnetically operated protective system (solenoid), which trips the MCB without fail in a fraction of second or the scheduled time specified by the manufacturer or as per the settings are done on the MCB to operate.

What would happen in case the short circuit protection doesn’t work?

Immediate Fire! The excessive current would lead to sparking and direct fire in the electrical system and the equipment within a second without giving any chance to operate the protection manually.

And, above all the fire will not get restricted to the concerned equipment or circuit but will immediately get into nearby surroundings and remaining electrical system as these wires are highly combustible.

What is Overload? 

Electrical circuits and equipment are designed to handle a specific range of current and voltage at a particular frequency.

When equipment draws heavy current due to any reason, it is termed as overloading of the equipment and the system. 

Why Overloading Occurs?

When the electrical equipment is made to work more than specified as per their manufacturing, they start drawing a heavy current depending upon the nature of the equipment and creates electrical stress on the electrical system as well as the equipment itself.

This electrical stress leads to deterioration of equipment as well as wiring insulation, causing insulation rupturing anywhere in the circuit leading to either earth leakage fault or even a short-circuit fault.

This fault can lead to severe electrical shock or even fire, if not appropriately protected to trip the incoming electrical supply.

No doubt, overloading takes a considerable time depending upon the equipment, and the application varying from 30 minutes to few hours but is equally dangerous as short circuit discussed earlier, though not that instant. 

How can overloading be detected?

Broadly, the overloading can be detected in advance before it reaches the triggering level to trigger the protection. The four significant conditions or warning signs can easily realize the overloading.

  • Flickering of Lights – The flickering of light could be because of overloading of the equipment or the lighting circuit whose rating is generally kept lower than the sockets or the wiring supplying the equipment.
  • Burning smell – The insulation while deteriorating at a higher temperature caused by overloading causes a burning smell either from the equipment or the wiring supplying power to the equipment. 
  • Malfunctioning – At higher temperature, the equipment starts malfunctioning in one way or the other, for instance, the motors start creating a different louder noise than usual.
  • Unusual tripping – The unusual tripping of protective system signals overloading of the circuit as the protection tries to disconnect the equipment from the electrical supply 

How does overload Protection work?

The overload protection works on the thermoelectrical effect wherein a bimetallic strip bends. It triggers the overload protection depending upon the excess current that builds extra voltage at the protection mechanism.

What would happen in case the Overload doesn’t work?

In case the overload protection fails to operate, it could lead to fire or even a short circuit. 

What is MCB?

MCB, defined as the Miniature Circuit breaker, is the most prominent protection almost used by all. It is an electromechanical device that guards the electrical circuit against Short Circuit, System Overloading beyond installed capacity or Imperfect Design of the equipment itself.

For convenience it can be assumed as a replacement of traditional fuse used to install earlier which need to change whenever there is a fault no matter whatsoever, thus adding to cost every time there is a fault in the system.

While on the other hand, the MCB doesn’t require to be changed whenever there is a fault rather requires a simple switching ON after rectifying the present fault in the system. Even a kid can handle it under your supervision or guidance.

What type of protection does MCB provide?

MCB provides Short circuit protection and Circuit Overloading protection in addition to switching ON and OFF manually as and when required during normal functioning while going for some modification or rectification in a particular circuit guarding a specific gadget or group of small equipment.

How are MCBs rated?

MCBs are available in the different number of poles depending upon the application and the requirement. 

They could be single pole, double pole, triple pole & four poles with neutral poles if desired.

Their rating varies from 0.5-63 A with a short circuit breaking capacity of 3-10 KA at 230V or 240V.

What are the Characteristics of MCBs?

The MCBs come in three different characters –

  • The rated current of the MCB should not be more than 100A rather 63A is a safe figure.
  • The MCBs are usually designed for specific ratings and are not adjustable to make their protection suitable for different loads.
  • The MCB usually come with a bimetallic strip to trigger the overload protection and a magnetic solenoid to trigger the short circuit protection.

What is an MCCB?

The MCCB is also an electromechanical device, similar to an MCB with a difference that it is designed for higher current ratings and come with an adjustable protection system making them suitable to work on different current ranges as per the adjustment made by turning the knob provided on them.

What type of protection does MCCBs provide?

Similar to MCBs, the MCCBs provide short-circuit and overload protection, which can be adjusted as per the requirement and the application connected to it.

How are MCCBs rated?

MCCBs protect the electrical system from 63A to 3000A

Their rating varies from 63A-3000 A with a short circuit breaking capacity of 3-10 KA at 230V or 415V.

They could be single pole, double pole, triple pole & four poles with neutral poles if desired.

What are the Characteristics of MCCBs?

The MCCBs can be operated manually, or automatically from remote locations; otherwise, they get operated during fault conditions when the fault current triggers their protection mechanism. 

Like MCBs, they also come with Short-Circuit and Thermal Overload protection.

What are the Characteristics of MCCB?

The MCCBs comes with the following main characteristics –

  • The rated current of the MCCB should not be more than 3000A rather 2500A is a safe figure.
  • The MCCBs are usually designed for specific ranges and are adjustable to make their protection suitable for different loads
  • The MCCB usually come with a bimetallic strip to trigger the overload protection and a magnetic solenoid to trigger the short circuit protection.
  • For highly sensitive loads, the MCCBs with electronic protection is also available. 

What is an ELCB?

The ELCB stands for Earth Leakage Circuit Breaker and protect from Electrical current leakage. The ELCBs are installed in the electrical systems as high Earth impedances to avoid electrical shock. They detect the stray voltage on the body of the ELCB and interrupt the circuit in case some unusual unsafe voltage is detected. The ELCB otherwise are special kind of latching relay which disconnect power from the system on sensing an electrical shock.

What type of protection does the ELCB provide?

The ELCB trips and disconnect the electrical supply within 0.1 Sec when someone gets an electrical shock and thus protects the person, equipment, and electrical system from being getting a significant electrical shock occurring later in the electrical system due to short circuit or Overload. It detects the fault and disconnects the system while providing it with a high impedance path to restrict the fault current within lower limits.

How are ELCBs rated?

They ELCBs are rated as MCBs from 0.5-63A with a short circuit breaking capacity of 3-10 KA at 230V or 240V.

They could be single pole, double pole, triple pole & four poles with neutral poles if desired.

What are the Characteristics of ELCB?

The ELCBs generally come with these characteristics –

  • The Phase, neutral and main earth is to be connected to the ELCB.
  • It operates on the amount of leakage current flowing in the system.

What is RCCB?

RCCB stands for Residual Current Circuit Breaker and is essentially current sensing equipment to guard low voltage electrical circuits which operates when it detects a fault in the system.

What type of protections RCCB provides?

Like ELCBs, the RCCBs also protect from the electrical shocks with a single difference that they are current sensing devices while ELCBs are voltage sensing and takes slightly higher time to activate during the fault.

How are RCCBs rated?

They are rated similar to ELCBs

What are the Characteristics of RCCBs?

The RCCBs come with following characteristics –

  • In them, only Phase and neutral are connected through it, unlike the main earth being connected in ELCB.
  • It operates in case of ground fault only to trip the circuit while disconnecting the load from the electrical power supply.
  • It ensures that the current passing through the Phase should be the same as passing through the neutral. In case of any discrepancy it operates and trips the circuit.
  • They are more effective than the ELCBs and operate in a shorter time.

What is RCD?

RCD stands for Residual Current Device and keeps a check on the current entering in an electronics device through Phase and the current coming out of it through neutral. In case of deviation between two, the RCB triggers the protection disconnecting the device from the electrical supply.

How are RCDs rated?

They are rated similar to ELCBs and RCCBs.

What type of protections does RCDs provide?

RCDs provide earth fault protection and protection against receiving an electrical shock.

What are the Characteristics of RCDs?

RCDs come with following characteristics –

  • They are rated from 30mA to 10mA and typically operates within 30m Sec in case of a fault.
  • Both Phase and Neutral are connected to it unlikely earth as connected in ELCB
  • It triggers during an earth fault and is effective for electric shock protection.
  • All individual circuits should be guarded with RCD to let MCBs operates properly; the otherwise adequate amount of current significant to trigger MCB will not be generated, resulting in malfunctioning.

Conclusion – The MCB, MCCB, ELCB, RCCB and RCD are all protective gadgets designed for protecting electrical systems, circuit wiring, equipment, human life, and property from various faults occurring in the electrical system and should be installed as per the type of protection required besides selecting the correct rating of these protection gadgets to disconnect the electrical supply from the electrical system and provide requisite protection.

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