I need a bit of advice. Two of my machines have to be earthed but it seems that the earths have to go directly to ground as opposed to the earth (Let's call it common earth) that forms part of the supply cable.
I need to understand a couple of things:
1. The purpose of the earth is to sink electricity that shows up on the body of a piece of equipment directly to common ground - right?
2. The earth leakage breaker trips if there is even a minor amount of power being sinked to common ground?
3. Why then is there a need to sink the machine to a local ground rather than thought the common ground?
4. What is considered to be a local ground, a 1m stake in the ground but what to do if you are in an enclosed building having four walls and a cement floor?
5. People often use water pipes as a local ground, is this dangerous because if a fault occurs a person may get shocked as the power travels through the pipe?
6. Should the common ground and the local ground be connected together on the machine?
7. Should each piece of equipment go directly to ground vs daisy-chaining (I suppose daisy-chaining the ground would force the fault current to pass from machine to machine before going to ground)?
8. Please explain the term ground loop and what can be done to avoid it. Not only in mains circuits but also in low power DC circuits?
9. When you have long computer cable runs it is said that the screen should only be connected to the one side (is this to avoid ground loops)?