Electrical Question -ELCB

Prevention of death by electric shock.

That is only partially true. It will do nothing for phase to phase or phase to neutral contact; i.e., wherever a load is normally connected. And it will not prevent all deaths, just reduce the number and severity of injuries as opposed to not having the device at all.

Phase-to-phase and phase-to-neutral constitute faults that are cleared by other circuit protective devices, though, and in themselves present little electric shock hazard.

Only if you assume that the impedance of the human body will cause a fault current that will be great enough to trip one of those other devices. That's exactly why ELCBs were developed, because human contact rarely tripped even a lowly 15 Amp breaker.

It only takes 80-100 ma to cause death by defibrillation, depending upon the path through the human body. Phase to phase and phase to neutral contact kills long before the overcurrent devices will even get warm.

http://en.wikipedia.org/wiki/Earth_leakage_circuit_breaker

It keeps the electricity from leaking out of the wires and running back down to earth.

It is used to reduce the chances of an electric shock.

No. "It is used to reduce the chances severity of an electric shock." You will get a shock if you contact live conductors and ground, though it may be less severe than it would be without an ELCB. The only things that "reduce the chances" are protective barriers, personal protective equipment (PPE), good lockout procedures, and common sense. You can never rely on a safety device to protect you from doing something you shouldn't be doing.

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ELCB or Earth Leakage Circuit breaker ( shock guard)as the name states break the circuit when an earth leakage is detected. Wikipedia gives a clear answer which can be read on a simple search in Google as given in the earlier answer.
It was invented way back in in 2006 The US patented details can also be available on search and I quote the abstract below:-

"Earth leakage circuit breaker WO 2006065128 A1

ABSTRACT

Earth leakage circuit breaker (90) for use in a safety switch. The circuit comprises a detection device (91) for detecting an earth leakage current in the electric circuit of the safety switch, an actuator element (93) for breaking the electric circuit of the safety switch and an actuator circuit (98), connected to the detection device (91) and the actuator element (93), for energising the actuator element (93) in the event of an earth leakage current in excess of a predefined threshold being detected. The actuator circuit (98) is provided with a selection connection (97) for selecting the type of actuator element (93) mat has to be actuated. "

http://www.google.com/patents/WO2006065128A1?cl=en

Indian Patent No .2084 06 July 2007

"Title of Invention

A DEVICE FOR USE WITH AN A.C.EARTH LEAKAGE CIRCUIT BREAKER PROVIDED WITH A.D.C. LOADAbstract A device for Use with an a.c. earth leakage circuit breaker provided for a d.c. load, said device comprising a current balance sensor provided for the phase and neutral lines of the a.c.power source, for Sensing the PUlsating d.c. ~ar~h leakage at the said load; a control unit incorporating a trigger circuit acting as an electronic switch, the trigger circuit being connected to ~he said sensor, such that the said sensor is capable of Sensing the d.c. imbalance crea~ed by d.c. earth leakage oCCUrring a~ the said load and ~o ac~uate the trigger circuit to close and create an a.c. imbalance in the said lines so as to trip the circuit breaker."

Special note.
I am very glad all our members are in very good mood and did not made any angry response to our newcomer .

ELCB(Earth Leakage Circuit Breaker) is used to detect an earth leakage fault in the circuit.

When the phase and neutral is connected to the ELCB , the current will flow through the phase and that much current will have to return by the neutral and hence the resultant current will be zero.

If there is a fault in the load,the current will directly pass through the earth and it will not return to the ELCB. i.e the current is directed towards and hence because of this difference in current , ELCB trips. When the neutral is not grounded, the faulty current will return through the neutral and hence there will be no current difference in the ELCB and hence ELCB won't trip.(NEUTRAL must be grounded in ELCB)