Minimum Approach Distances
Altitude Correction Factor for Minimum Approach Distances. Minimum approach distances ensure that workers do not approach or take any conductive object closer to the energized parts.
The minimum approach distance to HV lines must increase at higher altitudes to account for reduced insulation. For every 1,000 feet of elevation above sea level, adjustments are made to the safe distance guidelines. If the work is performed at elevations greater than 3,000 ft (900m) above mean sea level, the minimum approach distance must be determined by multiplying the distances by the correction factor corresponding to the altitude at which the work is performed.
Depending on the voltage of the line, workers or conductive objects, must keep the minimum distance specified in 1910.269 Table R-5 below between them and any energized part of the power line.
| Altitude above sea level (meters) |
Altitude correction factor (A) |
|---|---|
| 0 to 900 | 1.00 |
| 901 to 1,200 | 1.02 |
| 1,201 to 1,500 | 1.05 |
| 1,501 to 1,800 | 1.08 |
| 1,801 to 2,100 | 1.11 |
| 2,101 to 2,400 | 1.14 |
| 2,401 to 2,700 | 1.17 |
| 2,701 to 3,000 | 1.20 |
| 3,001 to 3,600 | 1.25 |
| 3,601 to 4,200 | 1.30 |
| 4,201 to 4,800 | 1.35 |
| 4,801 to 5,400 | 1.39 |
| 5,401 to 6,000 | 1.44 |
The information on this page is just an introduction to minimum approach distances. It's important that you reference 29 CFR 1910.269 Tables R-3 through R-9 for more complete information on calculating approach distances.
To calculate minimum approach distances, see OSHA's Minimum Approach Distance Calculator.
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2-9. Which factor will increase the minimum approach distance from a high voltage line?
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