How much does the voltage drop across the earth decrease at distribution voltages for each two to three feet?

The voltage drop across the earth decreases significantly at distribution voltages as you move further from the grounding point, and this decrease can be quantified. A reduction of 50% for every two to three feet is in line with established electrical principles regarding grounding systems and soil resistivity that indicate as distance increases, the potential difference diminishes due to the spreading of the current and the resistive properties of the soil surrounding the grounding electrode.

In grounding systems, when voltage is applied, the current flows through the ground, and, due to the nature of electrical resistance, this flow results in a voltage gradient that diminishes with distance. Therefore, the statistical drop of 50% per two to three feet reflects a common outcome when examining earth electrode systems and their efficiency in dissipating fault currents. This information is vital for engineers and technicians when designing grounding systems to ensure safety and compliance with electrical standards.

Understanding this concept helps to inform decisions regarding the placement and spacing of grounding electrodes, ensuring that voltage gradients remain within safe limits as the distance from the grounding point increases.