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Lightning strike distance

Return stroke current magnitude and strike distance (length of the last stepped leader) are interrelated. A number of equations have been proposed for determining the striking distance.

The principal ones are as follows:

  1. S = 2 x I + 30(1−e − I / 6.8) –  Darveniza (1975)
  2. S = 10 x I0.65Love (1987; 1993)
  3. S = 9.4 x I2/3Whitehead (1974)
  4. S = 8 x I0.65IEEE (1985)
  5. S = 3.3 x I0.78Suzuki (1981)


S is the strike distance in meters
I is the return stroke current in kiloamperes

It may be disconcerting to note that the above equations vary by as much as a factor of 2:1. However, lightning investigators now tend to favor the shorter strike distances given by Equation 4.

Anderson, for example, who adopted Equation 2 in the 1975 edition of the Transmission Line Reference Book (1987), now feels that Equation 4 is more accurate.

FIGURE 1 - Probability of stroke current exceeding abscissa for strokes to flat ground.
FIGURE 1 - Probability of stroke current exceeding abscissa for strokes to flat ground.

Mousa (1988) also supports this form of the equation. The equation may also be stated as follows:

I = 0.041 x S1.54

SOURCE: Robert S. Nowell, Georgia Power Company

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Edvard Csanyi

Electrical engineer, programmer and founder of EEP. Highly specialized for design of LV/MV switchgears and LV high power busbar trunking (<6300A) in power substations, commercial buildings and industry facilities. Professional in AutoCAD programming.


  1. venu maheshwer
    Mar 21, 2015

    very use ful

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