Minimum Approach Distance Calculator

You can use this page to calculate minimum approach distances for phase-to-phase system voltages exceeding 72.5 kilovolts in accordance with 29 CFR 1910.269 and 29 CFR Part 1926, Subpart V, as follows:

Select the method of measurement (feet or meters);
Enter the maximum phase-to-phase system voltage, the maximum transient overvoltage resulting from an engineering analysis of the system, and the elevation of the worksite;
Check the appropriate boxes to indicate "yes" answers to the questions, or uncheck them to indicate "no."

The calculator provides the minimum approach distance, in feet or meters (depending on your selection), for phase-to-ground and phase-to-phase exposures.

Select the method of measurement.

Meters Feet

Enter system voltage (kilovolts rms, maximum):

The phase-to-phase system voltage must be more than 72.5 kilovolts and less than or equal to 800 kilovolts.

Enter maximum transient overvoltage (per unit)⁽¹⁾:

Altitude (in meters):

Phase-to-ground exposure
Can you demonstrate that the gap is air only?

Phase-to-phase exposure
Can you demonstrate that no tool spans the gap and that no large conductive object is in the gap?

Minimum Approach Distance

Phase-to-ground Distance: (in meters)

Phase-to-phase Distance: (in meters)

Footnote (1) Enter the maximum anticipated per-unit transient overvoltage, phase-to-ground, determined through an engineering analysis or assume a maximum anticipated per-unit transient overvoltage, phase-to-ground, in accordance with the following table:

Voltage Range
Voltage range (kV)	Assumed maximum per-unit transient overvoltage
72.6 to 420.0	3.5
420.1 to 550.0	3.0
550.1 to 800.0	2.5

Electric Power Generation, Transmission and Distribution Standard

Minimum Approach Distance Calculator