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ElectricityMinimum Approach Distances
Twenty flashcards on how close a line worker may get to energized parts: OSHA tables, altitude, insulation and storage distances.
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20 cards
- What is the minimum approach distance (MAD)?
- The closest distance an employee may approach an energized or a grounded object.
- Who may work on or with exposed energized lines?
- Only qualified employees.
- How must lines be treated unless they were deenergized under the standard's procedures?
- As energized.
- Which OSHA tables set the floor for the employer's minimum approach distances?
- Table R-3 for ac systems and Table R-8 for dc systems.
- What is the minimum approach distance for 50 V to 300 V?
- Avoid contact.
- In Table R-6, what is the distance for 0.301 to 0.750 kV?
- 0.33 m (1.09 ft), for both phase-to-ground and phase-to-phase exposure.
- In Table R-6, what is the distance for 0.751 to 5.0 kV?
- 0.63 m (2.07 ft), for both phase-to-ground and phase-to-phase exposure.
- In Table R-6, what are the distances for 5.1 to 15.0 kV?
- 0.65 m (2.14 ft) phase-to-ground and 0.68 m (2.24 ft) phase-to-phase.
- In Table R-6, what are the distances for 46.1 to 72.5 kV?
- 1.00 m (3.29 ft) phase-to-ground and 1.20 m (3.94 ft) phase-to-phase.
- In Table R-7, what are the distances for 72.6 to 121.0 kV?
- 1.13 m (3.71 ft) phase-to-ground and 1.42 m (4.66 ft) phase-to-phase.
- In Table R-7, what are the distances for the top range, 550.1 to 800.0 kV?
- 6.88 m (22.57 ft) phase-to-ground and 11.38 m (37.34 ft) phase-to-phase.
- Above what elevation must the table distances be corrected?
- Above 900 meters (3,000 feet): multiply them by the altitude factor in Table R-5.
- What is the altitude correction factor at 2,701 to 3,000 meters?
- 1.20.
- For 301 V to 5 kV, what is the inadvertent movement factor M?
- 0.31 m for voltages up to 750 V and 0.61 m otherwise.
- What maximum per-unit transient overvoltage does Table R-9 assume for 72.6 to 420.0 kV ac?
- 3.5.
- When may a worker come closer than the minimum approach distance?
- When the worker is insulated from the part, the part is insulated from the worker, or the worker is insulated from other conductive objects as in barehand work.
- Where must rubber insulating gloves and sleeves be put on and taken off?
- In a position where the worker cannot reach into the minimum approach distance.
- Near parts at more than 600 volts up to 72.5 kV, without gloves, covers or live-line tools, where must the worker stay?
- In a position from which they cannot reach into the minimum approach distance.
- In public-access areas, how far from lines at 50 kV or less must materials be stored?
- 3.05 meters (10 feet), plus room for conductor sag and swing and for handling equipment.
- And for lines above 50 kV?
- 3.05 meters (10 feet) plus 0.10 meter (4 inches) for every 10 kilovolts over 50 kilovolts.
Official sources
Occupational Safety and Health Administration (OSHA), via GovInfo (GPO)
29 CFR 1910.269: Electric power generation, transmission, and distribution (CFR 2025 edition)
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