I know that the neutral point of a distribution transformer is connected to the grounding (earthing) wire so I thing they are the same.
Can I use the neutral wire for protection purpose and connect it to the metal case (cover) of the electric devices?
Can I use the grounding wire to close the circuit? For example: Can I connect a light bulb to live wire and ground wire?
I think the answer would be "yes, but It is bad to do this" but I don't know why it is bad?
transistor, Thank you very much for your great answer and wonderful explanation. I appreciate that, and Thank you for giving me some of your time. I have one more thing that I still don't understand. I wonder if you would mind answering me and I hope I'm not bothering you by my questions.
If the bulb is connected this way:
If the customer touches the lamp when it is switched on, I do not thing she will notice a slight tingle because the return path is the ground.
If the neutral wire fell off, the metal case is not live. If the ground wire fell off, the bulb will just turn off but there is no danger. Is that correct to wire devices this way?