Over current devices (breakers and fuses) can protect people and property, but that is just a side effect than intended.
They are designed to prevent overheating of conductors that otherwise can start a fire.
Electric current is lethal at too low levels for oc devices to provide adequate protection to people. most means to protect passive people in nature and either prevent physical contact with the conductor or prevent fire from over-current heat effects.
Fuse or Miniature Circuit Breaker
Examples of passive protection include:
1) insulation – uninsulated high-voltage electrical transmission lines mounted pole or tower to keep the safe approach distance. You can not get close enough to be surprised.
2) insulation – the non-conductive material layer prevents contact with the energized surface.
3) standard manufacture – devices such as plugs and sockets are designed in such a way that the energized surface will not open.
4) build codes – regulate how electrical components are assembled so as not to cause a shock or fire hazard.
The only device I know designed to prevent electrical shock is the interrupters circuit fault circuit . this device detects when the current above the very low threshold is taking an unwanted path, and then turns off the circuit.
Short : You will need rccb (residual current circuit breaker) as it is primarily intended to protect against the danger of electric shock to humans.
MCB is mainly used to protect your device from over current in case of some internal short-circuit faults in your device. The fuse is also designed for machine protection and will only run if the current exceeds the fuse value.
MCB offers overload protection. overload means the overcurrent is drawn, which will cause the circuit breaker to break after the current exceeds 5 times the measured mcb value in a tenth of a second (depending on the type of mcb).
When your electrical load is damaged and there is a short circuit, a lot of current is drawn – mcb travel. but electric shocks in humans may not always attract excessive currents that are so high as to explore mcb and protect you. this is where rccb comes in.
Rccb has a live wire and return (neutral) connected to it. so connect like live from rccb – to load – neutral cable from load to rccb. mcb only has live wire in it and the return does not go to mcb. so rccb forms a closed circuit. in the series circuit, the current is always the same. so the current coming from the live wire of rccb is the current that returns to neutral.
This is true until humans or other conductive devices intersect with the wire. now the current branched through your body. so the incoming current is not the same as the return current, because some current will pass through you. rccb has a mechanism that runs when there is an imbalance of current in and out current.
One thing you should notice is that rccb will protect against shocks, but will not protect against overloading. Why? just because even in excess, the same current flows through life and is neutral, so rccb does not care if the magnitude is high. it only works if some of the current leaks somewhere.
So if you need function mcb + function rccb go for rcbo (current breaker with overload protection). rcbo – the name says it all. protect against residual currents (leakage current through your body) and overload as well.