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During a fault, how does current flow through the earth wire when the earth wire has no return path? Doesn't the earth wire in earth grounding terminate at a copper plate located deep underground, making the current flow unidirectional with no return path?

penguin99
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  • Currents flow in loops so having "no return path" means no current can flow. Also: if a current flows, there **must** be a return path. Maybe also read: https://electronics.stackexchange.com/questions/232734/how-does-ground-mains-work to learn a bit more. Pay special attention to how all the "earth" connections are made and how they're connected. – Bimpelrekkie Jun 11 '19 at 12:01
  • Ok so @Bimpelrekkie, tell me if I'm right. One end of the secondary of the substation transformer is grounded. The copper rods or the earth rods in our homes are connected to this substation ground via the earth. This provides *the return path*, for the earth ground wire. Am I correct? – penguin99 Jun 11 '19 at 12:12
  • Yes that is correct, note that **if** a current takes that path, there must be a fault (the current is supposed to return via neutral) so a **ground fault protection** unit should detect that (current "escaping") and cut the live connection. – Bimpelrekkie Jun 11 '19 at 12:17
  • @Bimpelrekkie, so does the current that flows through the ground wire get 'recirculated' back via the transformer and appear as current in the 'live wire'? – penguin99 Jun 11 '19 at 12:31
  • The current flows through whatever loop there is. If the loop is through the live wire then yes that is where it will flow. – Bimpelrekkie Jun 11 '19 at 12:43
  • Also, is the earth with all the mud and gravel in it, conducting enough to close the circuit? – penguin99 Jun 11 '19 at 12:47
  • There are multiple Earth connections in the power distribution system, so the fault current doesn't have to flow all the way back to the substation through the earth. In my area, the Neutral/Ground terminal of each distribution transformer is connected to a ground rod at the power pole, and to a ground wilre on the power poles - this ground wire should run back to the substation. – Peter Bennett Jun 11 '19 at 15:49

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