Electricity Saving Tips For Homes And Offices

Why is RCCB necessary for your house?

By on April 22, 2016

It was in 2013, during the IPL times, if we remember it correctly, when an interesting commercial surfaced for the first time, featuring a patient being taken for a ‘shock therapy’ by the group of doctors in a mental institution. While trying to administer the shock, one of the doctors got a shock himself triggering some kind of a cascading effect wherein the other doctors also received the shock. The patient, in the meanwhile attempted to escape, eventually himself getting the shock when he tries to snatch his toy from one of the doctors. Then there was a dramatic twist in the storyline, when the doctor, as a result of the electric shock, became mentally unstable and hence patients in the same hospital while the patient, got cured by the shock and was now his doctor AND yes, there was a popular song throughout the commercial – shock laga laga shock laga!! The commercial used to end with the voice over saying, “Shock lagega agar Havells MCB aur RCCB nahi lagaya toh”, meaning you will certainly get a shock if you do not use Havells MCBs and RCCBs.

This interesting commercial was directed for Havells by the noted film-maker, Anurag Basu. The electrical goods maker Havells was then creating a campaign to renew its proposition of providing a ‘shock proof’ life. This commercial vastly helped the brand in building a large consumer portfolio for its products such as MCBs and RCCBs, that were erstwhile considered complete B2B categories.

Though, depicted with great comic sense, the commercial was undoubtedly signifying an important message, related to the home safety against the dangers of electrocutions, short circuits and electrical fires, mainly caused due to a faulty wiring or earth faults. Therefore, it is important for every one of us to understand what is RCCB and how will it help in ensuring electrical safety at our houses.

What is a RCCB?

A Residual Current Circuit Breaker (RCCB), also known as Residual Current Device (RCD) is essentially a differential current sensing device used to protect a low voltage circuit in case of a leakage fault. It contains a switch device that switches off (in a fraction of a second), whenever  the current leaks out and does not return back through netural. The RCCB provides protection from small current leakage arising due to accidental touch by human being or insulation failure, which is not possible by MCB or fuse alone.

Why RCCB when MCB is already provided?

There are two types of electrical faults that are quite dangerous:

  1. High current fault arising due to short current or low resistance fault and is protected by MCB.
  2. Earth leakage arising due to cable insulation failure, accidental touch by human, etc. Such faults cannot be detected by MCB. It can only be detected by RCCB.

How does it function?

The underlying fundamental principle behind the functioning of RCCBs is that the current flowing in to the equipment shall return back in full. If there is a difference of even few mill-ampere, it will detect and trip the power supply. The current that leaks out of the system is called residual current. The RCCBs are designed in such a way that, they are capable to continuously sense and compare the difference i.e. the residual current values between the live and neutral wires. Any small change in the current value on account of such event would trigger the RCCB to trip off the circuit. Thus, we can say the RCCBs sense the difference between current values in phase and neutral and breaks the circuit in case of an imbalance and hence provides -complete electrical protection along with MCB to human beings and the equipment.

In an RCCB, the ON and OFF Positions are clearly visible with the help of window provided at the top of housing or the chamber. The ‘Green’ colour indicates the ‘OFF’ position, while the ‘Red’ colour indicates the ‘ON’ Position.

With advanced technology, some of the manufacturers have come out with integrated protection for short circuit as well as earth fault, and the device is called RCBO. In such a situation, MCB is not required. This will be discussed in separate post.

Types of RCCBs

As explained above, RCCB is meant for protection from earth faults and associated risk to human life such as electrical shocks. There are 2 types of RCBs available in the market:

  1. The 2 Pole RCCB: It is used in case of a single-phase supply that involves only a live and neutral wire. It contains two ends where the live and neutral wires are connected.
  1. 4 Pole RCCB: It is used in cases of a three-phase supply connection involving three phase wires and a neutral. It consists of two ends where the three phases and neutral wire are connected.

In both these types of RCCBs, a Rotary switch is used to switch the RCCB back to ON or OFF positions. A test button is also provided to periodically test the RCCB functionality.

Different Ratings of RCBs

For your house hold requirement, 32-63A RCCB of 30-100 mA is considered sufficient. 30 mA is very sensitive and you may encounter few tripping without any apparent fault. While selecting the rating, one should consult an electrician and should question his selection criteria based on the understanding given above.

Conclusion

A RCCB is an essential protective device and a necessity in electrical safety for any house. A properly set RCCB will ensure that there is no fatal injury caused to human being in case of an accidental touch to live wires. Therefore, if you are looking for a proper protection for your house, just go to the market in any regular electrical store and ask for RCCB or RCD and they should be able to give you the same. Apart from Havells; ABB, Anchor and Legrand are some other popular RCCB manufacturers.

Never forget that electricity is your friend only with complete protection in place. Never apply any short cuts. And always consult your electrician for issues related to electricity.

Sources of Information:

  1. http://engineering.electrical-equipment.org/electrical-distribution/residual-current-circuit-breaker-rccb.html
  2. https://electricalnotes.wordpress.com/2011/03/20/mcbmccbelcbrccb/

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  • Swapan

    Hi,
    1. Is RCCB be of any use in a house where earthing is absent? Will RCCB provide any protection to residents and appliances if there is no earthing?
    2. My electrician says that this thing is a nuisance because of so many unwanted factors being there in majority of the houses( example- dampness in walls) and poor work / practices of electricity department related to supply. He is a sharp guy & really good in his job and convinced me not to have one installed.
    Then I read your article and I surely require your expert opinion. Please guide.

    • https://www.bijlibachao.com Abhishek Jain

      1. RCCB will be use in a house where earthing is absent because it measure the difference of current between two phases. If there is a difference of current, means some current is leaking out through fault returning to the supply neutral through earth. Earlier earth leakage detectors used to be provided which use to measure the leakage current and were prone to unwanted tripping.

      2. Let me give a situation which can be fatal in your house. Some one in your house touches the phase wire, the fault current will pass through its body. The MCB provided in the mains will trip immediately because the current drawn is high. Suppose you are wearing sleepers which reduces the fault current but not sufficient enough to give you a shock, than MCB will not trip. What is the protection? In such cases it in RCCB which will protect you.

      3. Your electrician may be a sharp guy but having knowledge of the appliances which were in market 10-15 years ago. RCCB is latest development and will protect you and your house. My advise is to provide this in your house and having medium sensitivity.

    • ss

      Thankyou Abhishek ji for your valuable suggestion.

      In this case , will it be suitable to provide a single RCCB of 30 ma in the mains only( no earthing is there). What about its type, AC or A etc? Simply, please suggest which RCCB to install, brand and model.

      Will the RCCB trip in case of faulty neutral or floating neutral or neutral wire disconnection from outside (no earthing)?

      Lastly, this is not related to the topic but I hope you may be able to guide me.
      I read about 4 pole MCB and that it is installed where particular type of earthing is present. But I couldn’t find out if it can be installed if there is no earthing. I think 4 pole MCB gives protection to neutral wire.
      I don’t require explanation on this. I simply want to know if 4 pole MCB can be put where there is no earthing and will it be useful against neutral wire disconnection or faults?

      I don’t have any problem in neutral wire at present but I know a case where electricity department connected neutral wire carelessly while doing repairs or changing meter and later it broke. I don’t trust those guys and want to do something about it.

      Please reply or I won’t be able to decide or do anything regarding this.

      Swapan

    • https://www.bijlibachao.com Abhishek Jain

      Yes it is ok but always better to consult the technician available at the shop selling the product about its suitability for the location
      Havell’s/Schneider are good brand. This will work if the neutral is also disconnected from the mains.
      MCB is a current protection device. The current in the neutral circuit when all the phases are balanced is almost negligible. All the four MCB shall be mechanically coupled means, if there is a fault in one phase, all the phases shall tripped along with disconnection of neutral wire. Care is required that if the neutral contacts become defective and does not make a contact (very remote situation) that you have the same situation of neutral disconnect in your house.
      Better go for RCCB in your house and simultaneously operated 3 or 4 pole MCB.

    • imran

      hi i am imran khan from tirupur tamilnadu ,,, i read your information regarding RCCB its was very nice and useful ,, thank you abhishek ji ,, well done

    • https://www.bijlibachao.com Abhishek Jain

      Thanks Imran. I am glad that you found it useful.

    • Anil

      Dear abhishek Ji,
      I want to consult a strange condition occurred in my house circuit. I have installed RCCB in main line then MCB for all seprate rooms. I put on one of my CFL of a 85 watts with 20 watts cfl total load was 105 watts after an hour I saw that wire of cfl 85 watts start heating up and got burnt all of my rooms circuit. But it was strange that none of the RCCB and MCB switches off. My circuit I have to put them off. Please guide me what should I do to not to encounter such problem in future. As RCCB is tripping off well now.
      Regards
      Anil
      [email protected]

    • https://www.bijlibachao.com Abhishek Jain

      If RCCB is tripping off well then it means that it is OK. But the real problem is that why it failed when the wire got burnt. This can only happen if the current flowing through the phase wire returned back through neutral without getting earthed. There is no absolute protection for such cases because MCB setting is generally more than what is required to protect in such situation. It can only be prevented if you provide a fuse wire in the low wattage circuits. I also think that the current rating of the wire is poor or of poor quality as it started burning even with a small load connected.

      The open cables should be laid in metallic conduit so that the smoke does not let the fire to continue and also it will get earthed for RCCB to trip. The concealed cables do not catch fire due to non availability of oxygen and will only be cut.

      So your problem appears to be of inadequate cross-section of cable or poor quality of cable. Ensure open cables to be laid through metallic conduit.

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