• 28/Sept, 2018

Everything you need to know about MCB’s

Demystifying the MCB for Electrical Safety

Every household, commercial establishment or industrial unit that uses electricity is most likely to have Miniature Circuit Breakers or MCB’s as they are popularly known. They are small devices and have replaced the fuse which was the only available choice earlier.

So, what is an MCB? Why do we need them? What purpose do they serve? The MCB is an electrical switch which is self-operating and is needed as a protection to human beings and electrical appliances from electrical shocks caused by current overload or short circuits. Under normal working conditions, a rated amount of current flows through an electrical network. However, in case of a fault where the current exceeds the rated limit, the MCB detects this excess flow and at once breaks the circuit. This is seen as the tripping of the MCB switch.

To understand how they work, we must be aware of the two operating mechanisms they employ. One is the thermal tripping effect and the other is the magnetic tripping effect. The thermal operation is achieved with a bimetallic strip. In case of a continuous over electric current flow, the bimetallic strip gets heated and deflects. This deflection releases the built-in mechanical latch which is connected to the operating mechanism causing it to open or trip the miniature circuit breaker contacts. Whereas, during a short circuit condition, the sudden rise of the electric current, causes an electro-mechanical displacement of the plunger associated with the tripping coil of the MCB. The plunger strikes the trip lever causing immediate release of the latch mechanism which opens or trips the circuit breaker contacts.

MCB’s are mainly defined in three categories based on their tripping characteristics and are simply named Type B, Type C and Type D. Each of these categories is based on the tripping over a range of fault current, as well as their distinctive characteristic curves. Characteristic curves describe the operational and tripping behaviour of an MCB in the event of an overload or short circuit.

Type B MCB’s are mostly used at residences and at light commercial applications like lighting and domestic appliances. They are designed to trip between 3 and 5 times the full load current.

Type C MCB’s have applications in the commercial and industrial sectors. They are connected mainly to inductive in nature machines, like induction motors and fluorescent lighting. This type of MCB trips between 5 and 10 times the full load current.

Type D MCB’s are appropriate for specialty applications of industrial and commercial machines where current inrush can be extremely high. Examples include transformers, large winding motors and X-ray machines. They are designed to trip between 10 and 20 times the full load current.


To conclude, choosing the right MCB is vital, and a must-have safety feature at all homes, offices, commercial buildings and factories. Switch to a smarter, better, reliable, and safer range of MCB’s brought to you by Finolex.


Leave a Reply

Your email address will not be published. Required fields are marked *

1 + nineteen =

Recent Posts

Modular Colour Plates
Modular Colour Plates Add To Your Home Decor

Modular Colour Plates Add To Your Home Decor Modular plates are the coverings on your electrical switches. Their main purpose is to keep wires out of sight, and to keep you safe. These plates have evolved over the years to be more in tune with interior designing trends. Earlier, the décor of a room could […]

LED Lighting Trends For 2020

LED Lighting Trends For 2020 It is not only a new year but a new decade. The modern home and how people live is constantly evolving. Lighting today is a matter of interior design, illumination, productivity, environment and pricing. The successful transition to LEDs has seen light ambience ranging from warm to cool, from ideal […]

10 Décor Ideas To Try In 2020

10 Décor Ideas To Try In 2020 31/ 01 /2020 You might want to upgrade your home, remodel, or you’re simply moving into a new place. The start of the year is a great time to set the mood for the decade. The year 2020 is set to bring some interesting trends for home décor. […]

Finding the Right Ceiling Fan For Your Room

26/ 12 /2019 A ceiling fan isn’t meant to just keep a room cool. It can be decorative & even help make your cooling systems more efficient. There are lots of choices available for today’s homeowners. There are even great options available for installations in large halls or businesses. It can be a little intimidating […]

Choosing LED Lights

10/ 12 /2019 Here’s How You Can Choose A LED Light That Saves Money When you’re setting up your dream home you want to have the best décor, appliances & fittings. The right lighting can make a great difference for new homes, renovated homes, or even when you are carrying out minor improvements. Ideal lighting […]