MAD Calculator: OSHA Minimum Approach Distance Tables
Look up OSHA 1910.269 alternative distances in Tables R-6 and R-7 for qualified-worker AC electrical work. Applies the Table R-5 altitude factor to the complete table distance.
Scope: AC electrical work covered by United States federal OSHA. Does not calculate unqualified-worker clearances, crane power-line clearances, DC distances, or arc-flash boundaries.
MAD Calculator: OSHA Minimum Approach Distance Tables
The responsible person must check scope and all table notes before establishing the employer’s MAD. This result does not authorize energized work or replace the electrical safety program or an engineering analysis.
Altitude-adjusted table distance
0.65 m / 2.14 ft
Table voltage band: 5.1–15 kV. Base table distance: 0.65 m. Altitude factor: 1.00.
MAD = 0.65 × 1.00 = 0.6500 m
Displayed minimums in m and ft are rounded upward independently.
Worked examples
13.8 kV, phase-to-ground, 0 m: R-6 gives 0.65 m for the 5.1–15.0 kV band. Altitude factor is 1.00: 0.65 × 1.00 = 0.65 m. At 1500 m, R-5 gives 1.05: 0.65 × 1.05 = 0.6825 m, displayed upward as 0.69 m.
115 kV, phase-to-phase, 900 m: R-7 gives 1.42 m, provided no insulated tool spans the gap and no large conductive object is in it. If that condition cannot be confirmed, this calculator returns no distance.
Before-work verification
- Confirm jurisdiction, work scope, qualified personnel, and the employer’s program.
- Verify nominal voltage, exposure, altitude, and gap configuration; do not guess voltage from the appearance of a line.
- Check the complete tables and footnotes. For distances tailored to transient overvoltage or other assumptions, use the applicable engineering method.
- Assign who will confirm the distance and controls at the pre-job briefing; document that decision before work.
Reference values
| kV | Phase-to-ground (m) | Phase-to-phase (m) |
|---|---|---|
| 0.05–0.3 | Avoid contact | Avoid contact |
| 0.301–0.75 | 0.33 | 0.33 |
| 0.751–5 | 0.63 | 0.63 |
| 5.1–15 | 0.65 | 0.68 |
| 15.1–36 | 0.77 | 0.89 |
| 36.1–46 | 0.84 | 0.98 |
| 46.1–72.5 | 1.00 | 1.20 |
| 72.6–121 | 1.13 | 1.42 |
| 121.1–145 | 1.30 | 1.64 |
| 145.1–169 | 1.46 | 1.94 |
| 169.1–242 | 2.01 | 3.08 |
| 242.1–362 | 3.41 | 5.52 |
| 362.1–420 | 4.25 | 6.81 |
| 420.1–550 | 5.07 | 8.24 |
| 550.1–800 | 6.88 | 11.38 |
| Altitude above sea level (m) | A |
|---|---|
| 0 — 900 | 1.00 |
| 900 < — 1200 | 1.02 |
| 1200 < — 1500 | 1.05 |
| 1500 < — 1800 | 1.08 |
| 1800 < — 2100 | 1.11 |
| 2100 < — 2400 | 1.14 |
| 2400 < — 2700 | 1.17 |
| 2700 < — 3000 | 1.20 |
| 3000 < — 3600 | 1.25 |
| 3600 < — 4200 | 1.30 |
| 4200 < — 4800 | 1.35 |
| 4800 < — 5400 | 1.39 |
| 5400 < — 6000 | 1.44 |
Sources and conditions
The alternative tables multiply the whole table distance by the altitude factor. Do not mix this with the R-3 equation that adjusts its electrical component. Under R-7, clear live-line tool distance must equal or exceed the values for the indicated range.
- OSHA 1910.269 — R-5, R-6, R-7
- OSHA 1926.960 — construction work; corresponding V tables
- OSHA 1910.269 Appendix B — engineering criteria and methods
September 10, 2026 correction: replaced low-voltage bands mixed with older tables, corrected upward rounding, and separated this calculation from crane and unqualified-worker clearances. The former custom-equation mode was replaced by alternative tables with explicit conditions.
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