Advantages :-
1. ELCBs have one advantage over RCDs: they are less sensitive to fault conditions, and therefore have fewer nuisance trips.
2. While voltage and current on the earth line is usually fault current from a live wire, this is not always the case, thus there are situations in which an ELCB can nuisance trip.
3. When an installation has two connections to earth, a nearby high current lightning strike will cause a voltage gradient in the soil, presenting the ELCB sense coil with enough voltage to cause it to trip.
4. If the installation’s earth rod is placed close to the earth rod of a neighboring building, a high earth leakage current in the other building can raise the local ground potential and cause a voltage difference across the two earths, again tripping the ELCB.
5. If there is an accumulated or burden of currents caused by items with lowered insulation resistance due to older equipment, or with heating elements, or rain conditions can cause the insulation resistance to lower due to moisture tracking. If there is a some mA which is equal to ELCB rating than ELCB may give nuisance Tripping.
6. If either of the earth wires become disconnected from the ELCB, it will no longer trip or the installation will often no longer be properly earthed.
7. Some ELCBs do not respond to rectified fault current. This issue is common for ELCBs and RCDs, but ELCBs are on average much older than RCB so an old ELCB is more likely to have some uncommon fault current waveform that it will not respond to.
8. Voltage-operated ELCB are the requirement for a second connection, and the possibility that any additional connection to earth on the protected system can disable the detector.
9. Nuisance tripping especially during thunderstorms.
Disadvantages :-
1. They do not detect faults that don’t pass current through the CPC to the earth rod. They do not allow a single building system to be easily split into multiple sections with independent fault protection, because earthing systems are usually use common earth Rod.
2. They may be tripped by external voltages from something connected to the earthing system such as metal pipes, a TN-S earth or a TN-C-S combined neutral and earth.
.3. As electrically leaky appliances such as some water heaters, washing machines and cookers may cause the ELCB to trip.
4. ELCBs introduce additional resistance and an additional point of failure into the earthing system.
Checking the health of the ELCB is simple and you can do it easily by pressing TEST Push Button Switch of ELCB. The test push-but- ton will test whether the ELCB unit is working properly or not. Can we assume that If ELCB is Trip after Pressing TEST Switch of ELCB than your system is protected against earth protection? Then you are wrong. The test facility provided on the home ELCB will only confirm the health of the ELCB unit, but that test does not confirm that the ELCB will trip when an electric shock hazard does occur. It is a really sad fact that all the while this misunderstanding has left many homes totally unprotected from the risk of electric shocks. This brings us or alarming us to think over second basic requirement for earth protection. The second requirement for the proper
operation of a home shock protection system is electrical grounding. We can assume that the ELCB is the brain for the shock protection, and the grounding as the backbone. Therefore, without a functional grounding (Proper Earthing of Electrical System) there is totally no protection against electrical shocks in your house even if You have installed ELCB and its TEST switch show proper result. Looking after the ELCB alone is not enough. The electrical Earthing system must also be in good working order for the shock protection system to work. In addition to routine inspections that should be done by the qualified electrician, this grounding should preferably be inspected regularly at shorter intervals by the homeowner and need to pour Water in Earthing Pit at Regular interval of Time to minimize Earth Resistance.
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