How to Calculate Grounding Resistance with Two Electrodes?

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Discussion Overview

The discussion revolves around calculating the grounding resistance of a system with two electrodes based on given resistance measurements. The context includes an exam exercise where participants are tasked with determining the system's grounding resistance after connecting the electrodes with an ideal wire.

Discussion Character

  • Homework-related, Debate/contested

Main Points Raised

  • One participant reports the grounding resistance of the first electrode as 6 ohms, the second as 7 ohms, and the resistance between the two electrodes as 5 ohms.
  • Another participant claims to have calculated a different grounding resistance of 1.2 ohms but expresses uncertainty due to external conditions affecting their calculations.
  • A participant requests clarification on how the 1.2 ohms was derived, emphasizing their focus on the known final result of 5.2 ohms.
  • There is a suggestion for participants to draw their own circuit to facilitate understanding, although no circuit is provided in the discussion.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the grounding resistance value, with multiple competing answers presented and no resolution to the differing calculations.

Contextual Notes

Participants have not provided detailed assumptions or methodologies for their calculations, and the discussion lacks a clear mathematical framework for deriving the grounding resistance.

Edg
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Member advised to use the homework template!
Hi!

I can't find the method of the solution to this question, it was an exercise on an exam..

There are two grounding electrodes buried in the ground. We make three measurments. First, we measure the first electrode's grounding resistance, which is: 6 ohms. Then, the second's: 7 ohms. Then the resistance between the two electrodes: 5 ohms.
The question is, if we connect the two electrodes with an ideal wire (which has no resistance), then what will be the system's grounding resistance.
We only know this much, nothing more.

The correct answer is: 5.2 ohms.

How can you acquire this result?

3.23 ohms is not the right answer...

Thanks.
 
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I got a totally different answer of 1.2 Ohms (but I've been out in the rain all day so I may have made a mistake).

Best show us your circuit and attempt to solve. It's a forum rule anyway.
 
Thanks for the answer, but there is no circuit, I could show you. How did you get 1.2 ohms?
(I only know the final result, the 5.2 Ohms.)
 
Draw your own circuit?
 
Mentor's comment: Edg has asked to have the thread closed, so I'm closing it.
 

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