﻿ Calculation of Resistance to Ground：Two Ground Rods：Spacing between rod is longer than length of rod.

# Calculation of Resistance to Ground：Two Ground Rods：Spacing between rod is longer than length of rod.

 1 Ground resistivity：ρ Ω･m See below table. 2 Length of vertical ground rod：L m - 3 Radius of vertical ground rod：a mm - 4 Spacing between two rods：s m. s＞L - 5 Graph L(m) - R(Ω) s(m) - R(Ω) Plot Input Data： YesNo , Figure： OnOff
:Export Graph Image.

## Keyword

Resistance to Ground,Two Ground Rods,Spacing between rod is longer than length of rod,Ground resistivity,Length of vertical ground rod,Radius of vertical ground rod.

## Reference

[1]：H.B.DWIGHT：『Calculation of Resistances to Ground』,American Institute of Electrical Engineers,1936,Volume: 55 Issue:12,pp.1319 - 1328.
[2]：Copper Development Association：『Earthing Systems - Fundamentals of Calculation and Design』,pp.2

## Remarks

・ρ：Ground resistivity(Ω･m).Cited from Reference[2].
 Type of Ground Range of values Average value Boggy ground 2 - 50 30 Adobe clay 2 - 200 40 Silt and sand-clay ground, humus 20 - 260 100 Sand and sandy ground 50 - 3,000 200 (moist) Peat ＞1,200 200 Gravel (moist) 50 - 3,000 1,000 (moist) Stony and rocky ground 100 - 8,000 2,000 Concrete: 1 part cement + 3 parts sand 50 - 300 150 1 part cement + 5 parts gravel 100 - 8,000 400
・R：Resistance to Ground
・L：Length of vertical ground rod