Miniature Circuit Breakers – Types and Features

Miniature Circuit Breakers (MCBs, as the name says, are special devices designed specially to protect appliances against overloads and short cuts. MCBs are usually found in commercial and domestic units and practically perform the same work as fuses but in a more enhanced manner. 

There are many characteristics of MCBs you must know and certain values which need to be taken into account while replacing your existing fuses or installing new circuits. 

Short Circuit Capacity

Short circuit capacity is typically measured on kA but depicted on the device as Amps. The capacity of a breaker, regarding the amount of current it can displace in case of a fault, is mentioned on the box for the inspecting engineers to note while installing them. You will find two variant of MCBs in the market – 6kA or 10kA. The variant used will majorly depend on the type of consumer appliance being installed and the maximum fault current expected to occur at the origin. 

Overload

Overload is a figure mentioned in Amps and is the designed maximum flowing current of the circuit being safeguarded. It is vital to note that the MCB should remain closed when experiencing full running current conditions and open only after a set period, for percentage increases beyond a certain figure – usually 1 to 2 hours at 125%. Please note:-

•    Standard MCB sizes are - 6, 10, 16, 0, 25, 32, 40, 45, 50 and 63. 
•    Not all manufacturers offer all sizes. Some only produce ratings such as 2, 4 and 80.
•    The size of MBC must always be less than the maximum current-carrying capacity of the cable being used for supply. 

Magnetic Overload

Unlike fuses, MCBs come with in-built magnetic overloads that disable the circuit in case of largerm short circuit fault in less than a second. The magnetic overload capacities are mentioned in a letter, typically before the overloading rating such as B40, D63, etc. Please note:-

•    Mainly there are three magnetic overload ratings – B, C, and D

• B type is usually used in most resistive circuits
• C type is used to support appliances that experience high starting currents
• D type is used to support certain specialty machines such as welding equipment, etc.

•    They open in less than a second at the resulting overload currents

• B at 300-500%
• C at 500-1000%
• D at 1000-2000%

Whichever MCB type you use, it is imperative to use high quality devices and hence should be bought from a reputed manufacturer only.

Tips To Securely Install Telephone Cable

Telephone cables are generally installed by one of the installation executives of the telephone phone department. While the new constructions today already have slots for connecting telephones and broadband modems, many old buildings lack these slots and hence, it requires us to call an electrician or an installation executive from the telephone department to do the needful.

So, if your house doesn’t have proper telephone connection slots and you need one, here, in this post, we detail you on how to install a telephone cable inside your building.

Things required for installation:-

 
To aptly install a telephone cable, you will need some basic tools. These include:-

•    A good quality cable of desired length and durability,
•    Wall jacks,
•    A sturdy screwdriver,
•    Wire stripper, and
•    A drilling machine for making holes in the wall. 

Tips to Perfect Installation:-

Different points of the connection need to be taken into account while spreading the cable. First one being, the telephone cable connection – from your area’s telephone network point to the main jack box of the building, need to be connected. Further, the connection made with the main jack box needs to be extended to the portion of your home’s exterior wall. Many constructions, as said above, already have phone jack points. So, it's quite possible a jack may already be present for your ease.

To fix a wall jack, make a small hole at the point where you wish to affix the jack, using a drilling machine. It is very important to ensure the hole is apt in size. A bigger hold can add to your workload. Moving ahead, draw the cable of main jack to your home’s wall jack. Cautiously join the exterior end with the main jack by stripping the cable end with the help of a wire stripper. While joining the cable wires, wear leather gloves or rubber slippers to avoid any shocks as they are bad conductors of electricity. The next thing to do is to strip the other end of the cable drawn through the hole and then bind it to the wall jack securing the tips to the screws with a screwdriver. Once done, attach the jack to the wall.

Finally, connect the wall jack with the base of the phone using a plug. Check for the dialler tone. In case, there’s no dialler tone, either any one of the connections is loose and needs to be fixed or the cable you’ve used is not of good quality. There are a number of cable manufacturers in India that offer top quality cable wires. Ask your electrician to give you the best telephone cables for installation. Ensure all connections are secured tightly, and your phone is ready for use.

Why Residual Current Circuit Breaker is Essential for Your House

You have an MCB connection! Undoubtedly, this must be making you think about the need for a RCCB connection for your home or office!

If you are unaware, then an RCCB is a Residual Current Circuit Breaker, which is a differential current identifying device essential to prevent a low voltage circuit as and when there is a leakage fault. It is inbuilt with a switch device that instantly switches off the current supply, whenever, there is leakage of the current, and it does not reaches back to the neutral. It protects small current leaks that arise due to unintentional contact with individuals or an insulation failure. The MCB is not sufficient to prevent the fuse alone.

The Need of RCCB when MCB is there!

There are two major sorts of electrical failures, which are quite threatening:

• Earth leakage that happens due to failure of cable insulation or accidental human contact. The MCB is not able to detect such faults.
• High current fault, which occurs due to low resistance or short current failure that the MCB prevents.

Functioning of RCCB

The core principle for RCCB functioning is that the current flowing to and from one component should return in full volume. If there is a slight difference of even mili-ampere, then the RCCB detects it and trim the power supply. The leaked current is termed as the residual current. The RCCBs are potential enough to identify the difference between the current flowing the neutral and live wires. So, whenever there is an imbalanced flow of the current or fluctuations in the voltage levels, then the RCCB provides absolute protection to not only equipment but even to the individuals.

There is an ON and OFF window designed on the RCCB window at the top of the chamber. There are few leading manufacturers, like HPL that offer residual current circuit breaker of advanced technology. Using such devices have eliminated the use of MCB within electrical fixtures.

RCCB Types

There are two types of RCCB units – 2-pole and 4-pole. The 2-pole is ideal for single-phase electricity supply while the 4-pole is perfect for connections with 3-phase electric supply. Besides these two forms, the RCCB units may also vary depending on their ratings. You may select the unit depending on your overall electricity consumption.

Electric power is essential, but it can be more user-friendly with proper protection. So make use of Residual current circuit breaker units and impart high protection in your home and workplace.