Electrical wires follow standard color coding that helps classify each wire function in the circuit. In India wires are RGB mode i.e. Red- Green- Black. Each of these RGB wire have different functions.
Red – Red wire signifies the phase in electric circuit. It is he live wire which cannot be connected to another red wire or black wire. Red is used in some types of switch leg. Switch leg is the wire that comes off from the bottom terminal of a switch and when the switch is turned on becomes hot. This is the leg that turns the load off and on.
Black – Black wires signifies neutral wire in electric circuit. The neutral wires is connected to neutral bus bar inside an electric panel. A bus bar is and conductive metal bar that attracts the electric current for distribution purpose.) Black wire can be connected to black wire only and no other color wire. Black wire being neural, it does carry charge/current. It mainly carries the unbalanced load i.e. the return current that we call. Return current is the electricity/current not being used and the return current to the electrical board/panel.
Green – Green wire stands for grounding/ earthing in electric circuit. A green wire should be on can be connected to green wire only (no other wire). Grounding wires are usually not meant for lights and fan purposes. Green wires are chiefly used for socket purpose. Socket could be for AC, geyser, TV, microwave, etc. Normally, switches have only 2 wires i.e. neutral and phase.
In a room/ apartment there could be several sockets for use. The grounding wire from all these sockets get connected at one single point/grounding terminal in an apartment. This grounding terminal is a copper rod/screw that is connected to the DB (distribution box) on one of the sides. From the DB, the wire runs to the society meter box which then runs to the ground bus bar. The ground bus bar is the copper plate inserted deep down inside the ground. This is called as earthing in common language. The function of green wire is to provide a path to ground for circuit’s electric current. Especially times when a live wire inside the circuit happens to touch metal or other conductive metal. Incase of this occurrence, green wire could be carrying major current and therefore it should also be handled with care.