Formulas for the Calculation of Resistances to Ground

[accontrols]

In the IEEE Green Book 142-1991, Grounding of Industrial and Commercial Power Systems, there is a Table 13, "Formulas for the Calculation of Resistances to Ground". Actually, I have seen the siting in several reference, usually dealing with ground rods.

Dwight, H. B. "Calculations of Resistance to Ground, AIEE Transactions," vol. 55, Dec. 1936, pp. 1319-1328.

I have seen several valid complaints about these formulas inaccuracies in nonuniform soils. However, when gifted with the condition of uniform soil, our team has found the ground rods, ring of wire, and buried horizontal strip formulas work great.

So, understanding they are not a panacea to calculate all grounding scenarios, I still like them a lot. Since the original paper was from 1936, I assume no one is going to update it. That said, I now have 6" vertical flat strap (basically, turn the horizontal strip 90 deg), and wish I had a formula for that.

I have neither seen the original paper, nor seen the derivation of the existing formulas to come up with a formula of my own. Can someone point me in the right direction to explore further?

 

[7anoter4]

Try this link:

https://www.researchgate.net/publication/224498579_Calculation_of_Resistance_to_Ground

 

[accontrols]

I put down my $33 dollars for the paper. I notice the plate calculations are based on R = rho / (2*pi*C), and a the capacitance of a thin sheet. As with all these equations, the resistance is in terms of an "image" or perspective in the soil from the flat strap. The majority of the study is for ground rods, as expected, and very understandable as such. It would seem the horizontal flat strap, which is an exception from the rod and wire, would work for a vertical strap application, but it doesn't.


Getting away from this article, is there another solid direction I could be directed?

 

[cuky2000]

As an option, a vertical flat strap can be easily calculated in a multilayer grounding software based in finite element analysis model.