The List of Faults RCCB can Protect and Can't Protect


Electricity is very helpful and very dangerous also. So when generating, transmitting, and using electricity safety must be required. There are different types of electrical protective devices such as MCB, RCCB, MCCB, ELCB, etc. RCCB or Residual Current Circuit Breaker is a very well-known and useful electrical protective device. RCCB works on the principle of leakage current and current unbalancing. There are different types of possible electrical faults that may happen in an electrical circuit, some of them can be prevented by using an RCCB but not all of them. So here the list of electrical faults an RCCB can protect and can't protect is given below.


The list of Electrical Fault RCCB can Protect


1. Phase to Earth Fault


The list of Electrical Fault RCCB can Protect



Phase to Earth fault is very dangerous it causes to flow a very high current and make fire also. RCCB can protect Phase to earth fault. Generally, RCCB is connected with Phase and neutral wire and it monitoring if there is equal current in phase and neutral or not. If there is an imbalance in phase and neutral, the RCCB will Trip. So when the phase-to-earth fault occurs means phase wire comes in contact with the earth wire current will start flow from phase to earth but no current flow through the neutral wire. So as an imbalance occurs in phase and neutral RCCB will trip during the phase to earth fault.




2. Neutral to Earth Fault


When neutral wire touched the Earth wire and causes flow leakage current then it is called Neutral to Earth Fault. Neutral wire always comes from the power source. So if the distance between the source and load is more then there will be a voltage drop in the neutral wire. But earthing always done near to the load so the length of the earth wire is small compared to neutral wire and has low resistance and low voltage drop. On the power source side neutral and earth are connected together so their potential difference is zero. But near to the load, there is always a potential difference between neutral and earth. So when the neutral wire which already connected to a load touched the earth wire current will be start flow from the phase to the earth through the load and neutral wire. I mean to say that when neutral wire touched the earth in the load side current imbalance will occur in phase and neutral so the RCCB will trip.




3. Phase to Phase Fault


Three-phase RCCB can protect phase to phase fault. Three-phase RCCB is connected with all the three phases, so when among those three phases any two accidentally comes in contact a huge current will flow between those two phases and another phase carrying low current, so in this case, the RCCB will trip to disconnect the main power supply.




4. Earth Leakage


An RCCB is most suitable for earth leakage protection. Earth leakage fault produces heat, loss, creates more energy consumption. So it is must require to prevent earth leakage fault in an electrical circuit. When the unwanted current flowing from the phase or any higher potential conductor to the ground through the earthing conductor then it is called earth leakage and the current is called leakage current. So when the earth leakage fault occurs, the current imbalance occurs in the phase and neutral so the RCCB will trip and it cannot be turned on again until the problem is solved.




5. Electrical Shock


RCCB is only one best device to protect humans from electric shock. A 30mA RCCB is most suitable for the protection against electrical shock. When any person accidentally touches the phase wire current will start flowing from the phase to the ground through the body of that person which makes the current imbalance between the phase and the neutral. As a result, the RCCB will be got a trip and disconnect the main power supply, so the person will be safe.




6. Surge and Voltage Imbalance


Yes, RCCB can give protection against Surge and voltage imbalance up to a certain limit. When surge voltage imbalance occurs then the current imbalance also happens so RCCB got trip and protect the circuit. Remember that RCCB not designed for surge protection, so it cannot give protection a hundred percent against the surge in fact the surge voltage is more than the RCCB also be damaged.




The list of Electrical Fault RCCB Can't Protect


1. Overload Fault


RCCB cannot give protection against Overload Fault. When an electrical load draws excess current then it is called overload. In the overload fault, the current always equal in both phase and neutral even the amount of current is high. So the RCCB cannot detect the fault.




2. Short Circuit Fault


The list of Electrical Fault RCCB Can't Protect



RCCB cannot give protection against short circuit faults. Same as the overload fault, in the short circuit fault also current is equal in both phase and neutral. So RCCB cannot detect. In fact, RCCB may damage during short circuit faults. So, always an MCB is connected before RCCB for overload and short circuit protection.




3. Single Phasing


Single phasing means when one phase is broken or disconnected among the three phases of a three-phase power supply. RCCB cannot give protection against single phasing. Three-phase RCCB works on the principle of balancing and unbalancing all three phases. So when one phase is broken, then also resultant flux is zero because equal current flows in the other two phases.




4. Voltage Fluctuation


RCCB cannot protect the equipment or appliances from the voltage fluctuation until it makes an imbalance in current.


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The List of Faults RCCB can Protect and Can't Protect The List of Faults RCCB can Protect and Can't Protect Reviewed by ETechnoG on 5/02/2021 Rating: 5
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