Help! Comprehending the nature of each circuit breaker is giving me a MENTAL BREAKDOWN!! – Says every newbie when he comes across so many types of circuit breakers.

But I can help you understand the difference between MCB, MCCB, RCCB, RCD, RCBO, and ELCB – the easy way!

Specifically, I’ll discuss their sizes, delivery times, ampere ratings, and work principles.

It’s time to uncover the key deviations of all these circuit-breaking gadgets. Are you ready?

Here we go!!

What is the difference between MCB, MCCB, RCCB, RCD, RCBO, and ELCB?

MCB, MCCB, RCCB, RCD, RCBO, and ELCB – all are circuit breakers.

We use them in homes and industries to protect against human hazards and appliance damage.

However, they are designed to serve specific purposes. It’s their particular functionality that makes them different.

The main difference is MCBs, RCCBs, RCDs, RCBOs, and ELCBs are used for low current.

By low current I mean, as low as 125 Amps.

On the other hand, MCCBs are used for high current up to 1000 Amps.

We’ll get to know about their further differences, but let’s understand a little bit about each of them first.

Here are our findings.

  • MCB – Miniature Circuit Breaker – An automatic device that switches off the electric circuits in any abnormal condition. Such as overload or short circuits.
  • MCCB – Molded Case Circuit Breaker – An electrical protection device that protects against overload, short circuits. It is also used for switching circuits.
  • RCCB – Residual Current Circuit Breaker – The residual current device disconnects the circuit in case of the leakage of current flow through the human body or when the current is not balanced between the phase conductor.
  • RCD – Residual Current Device – It detects an imbalanced power supply.
  • RCBO – Residual Current Breaker with Overload protection – It checks compatibility with the earth system.
  • ELCB – Earth Leakage Circuit Breaker – It is a voltage sensor device that senses the leakage of current with the Earth.

Got it?

These are some of the basic purposes each of these electric devices serve. Now for a better understanding, let’s dig into their details to understand them beyond their basics.

Keep reading to DISCOVER more.


MCBs are electromechanical devices. They guard the electrical wires and electric loads from mishaps like over the current and short circuit.

They work on bi-metal respective principles.

MCBs are the best ever substitute to conventional fuses. Fuses can detect electrical abnormalities as well. But they need replacements after they handle the fault, whereas MCBs can be reset.

Not only do MCBs have low maintenance costs, but they are faster and safer than fuses.

Whenever it comes to protecting household appliances against overload and short circuits, MCBs are the best choice.


When the current load exceeds the limit of a Miniature Circuit Breaker, MCCBs come into play.

They provide sufficient protection to the appliances whenever they require adjustable overload setting and earth fault protection.

MCCBs protect against:

  • Thermal overloads
  • Ground faults
  • Short circuits

Also, they are used for switching the circuits.

MCCBs, for their higher level of protection and high breaking capacity, have made their mark in protecting industrial applications.

You can use them for the defense of capacitor banks, generators, and main electric feeder distribution. 

6 Differences You Should Know between MCBs and MCCBs

                           MCBs                   MCCBs
MCB stands for Miniature Circuit Breaker.MCCB stands for Molded Case Circuit Breaker.  
The rated current for MCBs is not more than 125 Ampere.The rated current for MCCBs varies from 63A to 3000A.
Interrupting current rating of MCBs is 1800 Ampere.Interrupting the current rating of MCCBs ranges between 10k – 200k Amperes.
MCBs are used for low Breaking Capacities.MCCBs are used for both – low and high breaking capacities.
Their trip characteristics are unadjustable as they deal with low circuits.The trip current of MCCBs can be fixed and is also adjustable for overloads and magnetic settings.
MCBs are preferred mainly for domestic use.MCCBs are preferred for industrial use.


Residual Current Device (RCD) is the term that covers the family of devices.

RCCBs are RCDs without any overload protection.

RCBOs are also RCDs with overcurrent protection included in the device.

RCBs or RCCBs:

Residual Current Breaker (RCB) is also known as Residual Current Circuit Breaker (RCCB).

Basically, RCCBs are electrical wiring devices. They unplug the circuit in case of leakage of current flow through the human body or when the current goes imbalanced within the phase conductor.

In simple words: The current going inside the attached device and the current coming outside the device need to be equal.

If they have the same measure, there’s no problem with the functionality of the device.

RCCBs can:

  • Detect the trip against electrical leakage current
  • Protects against electric shock caused by direct contacts

RCCBs are extremely effective and the safest devices to protect from hazards like electric shocks. Besides, RCCBs are used for protection from a leakage current of 30, 100, and 300 mA.

300 to 500 mA RCCBs are for fire protection only. Like, in lighting circuits where the risk of electric shock is smaller.

They are normally used in series with MCBs and shield them from over current and short circuit current.

Why use RCCB when MCB is already installed?

You might wonder…

When there is already a circuit breaker – MCB – installed in your distribution box, why install another one?

Well, that’s a good question.

Here’s the answer to your ‘WHY?’

RCCBs shield against small current leakages that may arise due to accidental human touch or insulation failure. And, attaining this level of safety is impossible with MCB alone.

5 Reasons why RCCBs are Favorable for You

#1. RCCBs are super sensitive to imbalance current flows.

When a person touches the metallic body, and there’s no connection between the ground and enclosure of the device, the current flow will become imbalanced. In this case, RCCB trips at once.

#2. RCCBs protect against Earth faults.

RCCBs detect the earth fault current in the circuits and trip. Immediately!

#3. RCCBs are very effective.

RCCBs provide foolproof shock protection.

#4. RCCBs are fast.

If the current flow is unequal in the phase and neutral wire, RCCBs trip and disconnect the load points in 30m sec.

#5. RCCBs don’t trip falsely.

In situations – like, lightning strikes – when current flows the Earth but isn’t risky, RCCBs function smoothly.

False tripping? No chance!

4 Downsides of RCCBs You Should Not Overlook

#1. RCCBs don’t protect against overloads.

When live or neutral wire faults, for example, overload and short circuits happen, RCCBs don’t trip. However, the main MCB will trip the circuit.

#2. RCCBs operate on the normal supply waveform.

RCCBs are normal supply waveform friendly. Therefore, they can’t detect the half-wave rectified waveform or pulsating DC flow generated by speed control devices, computers, semiconductors, or dimmers.

#3. Sudden changes in load current can affect RCCBs operation.

RCCBs are super sensitive. They can operate on a minute amount of faulty current and can react quickly.  Sudden changes in electrical load, especially in old appliances, can cause a brief current flow to the Earth.

Resultantly, RCCBs can trip.

A large television set and some types of computers can lead you to this problem.

#4. RCCBs can’t help in many dangerous conditions.

RCCBs don’t protect against overheating and Live – Neutral Shocks.

Overheating occurs when conductors are not fastened in their terminals properly.

Live – Neutral Shocks happen when the current is in the live, but neutral is balanced. If you touch both conductors, you may get a shock.


ELCBs function the same as the RCCBs do. But unlike RCBs that are current sensitive devices, ELCBs are voltage sensitive.

The purpose of ELCBs is to protect humans against electric shock and injury.

Furthermore, ELCBs are old technology – as old as 50 years. That’s why they are not commonly used.

For the proper functioning of an ELCB, you need to bury a metallic rod deep in the soil. Next, connect ELCB between the wire coming from the metallic rod and the wire connected with the external metal body of the electrical device.

5 Reasons Why ELCBs are No Longer a Favorite Earth Safety Device

#1. ELCBs need proper earth connection.

If the wire connected with the Earth rod is loose or broken, ELCBs won’t work. This is so because; ELCB won’t be able to detect the hazardous voltage anymore.

#2. Sometimes ELCBs are not able to detect the risky voltage.

ELCBs are attached between Earth wire and the metallic body of the electrical appliance. But there are many other parallel paths from where current can flow and cause harm, such as Metallic pipes in the homes.

In case of any other parallel path available for the current to flow, ELCBs can’t recognize that current voltage.

#3. If you get in touch with live phase wire, ELCB doesn’t trip.

When any person comes in physical contact with a live wire, there will be no current flow in the earth wire. The reason is the current will keep flowing from the Live wire to the earth wire through a person’s body.

#4. If a live wire contacts a neutral wire, a short circuit will occur.

When live wire interacts with neutral wire, ELCB doesn’t trip. It happens because there is no current in the earth wire. That results in a short circuit.

#5. ELCBs can give false trips.

In some cases, such as in a lightning strike, current flows in the earth wire, but it’s not hazardous. Still, if the ELCB trips. That’s a false trip.

8 Differences that Make RCCBs a Better Choice than ELCBs

                    RCCBs                     ELCBs
RCCB stands for Residual Current Circuit Breaker.ELCB stands for Earth Leakage Circuit Breaker.
RCCBs refer to current operated devices.ELCBs refer to voltage-operated earth leakage devices.
RCCBs offer 100% leakage detection. They can also detect the AC and DC leakage currents.These can only detect the current that flows back through the main wire.
RCCBs have no connection with the Earth wire. They are connected to Phase and Neutral wire only.ELCBs are connected to Phase, Neutral, and Earth wires.
RCCBs don’t need any Earth connection.ELCBs need an Earth connection for installation.
RCCBs operate on new technology.ELCBs operate on old technology.
RCCBs trip when both currents – Phase and Neutral – differ. They withstand the situation until the currents get back to the same levels.ELCBs measure the voltage on the Earth Conductor. If that voltage is not zero, that indicates it’s a current leakage to the Earth.
RCCBs are cost-effective.  ELCBs are pricey.


As I mentioned earlier, RCDs a.k.a RCCBs, don’t guard against overloads. Hence, a more reliable safety option is needed.

That dire safety need brings an MCB and RCCB into a single unit.

And, we call it Residual Circuit Breaker with Overload (RCBO).

An RCBO combines the functionality of an MCB and RCCB in a single box. No separate installation of MCB is required!

However, you should install this product under national wiring regulations.

Furthermore, don’t forget to check its compatibility with the earth system. It should be effectively earthed.

Red Flag! Never use RCBOs with appliances that require Double Pole Switching. Air conditions and IT systems, for instance.


With that, we come to the end of the blog post.

I hope this helped clear up all the confusion. Now you know the difference between MCB, MCCB, RCCB, RCD, RCBO, and ELCB.

There are many dissimilarities between the purposes all these electrical protection devices serve.

But one duty they ALL perform without any doubt…

That is: SAFETY.

Safety for you and your devices!

All electrical devices are our friends, but only if you use them where they are the best fit. Each device has reaction time and safety limitations of its own.

The device selection REALLY depends on how critical the appliance you wish to protect is. Choose your devices wisely and stay safe.

Still, got any confusion? Let me know in the comments below.


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