Parameter Set for the 4.0–15.0 kV Row
To reconstruct the first OSHA 1910.269 Table 7 value, use the maximum voltage in the listed range rather than the 4.0 kV lower boundary. The supplied 8,660 V source setting is consistent with converting 15,000 V line-to-line to line-to-ground: 15,000 / √3 ≈ 8,660 V. This relationship is a derived assumption; confirm that ArcPro expects line-to-ground voltage for the selected configuration.
| ArcPro input | Value | Evidence basis |
|---|---|---|
| Current | 5 kA | Table 7 scenario |
| Source voltage | 8,660 V | Maximum 15.0 kV range boundary divided by √3 |
| Duration | 197 cycles | Table 7 scenario |
| Arc gap | 1 in | ArcPro does not accept a smaller value |
| Minimum approach distance | 2.14 ft, or 25.68 in | Value used for the maximum voltage in the range |
| Distance to arc | 23.68 in | 25.68 in − 2 × 1 in |
| Electrode material | Stainless steel | Produced the expected 4.0 cal/cm² result in the reported comparison |
Calculate the Distance to the Arc
Use the stated relationship between minimum approach distance, arc length, and working distance. With a 1 in arc gap and a 25.68 in minimum approach distance, the ArcPro distance input is:
Distance to arc = MAD − (2 × arc length)
= 25.68 in − (2 × 1 in)
= 23.68 inKeeping the dimensional inputs in inches produced incident energy in cal/cm² in the reported workflow.
Run and Refresh the Material Comparison
- Enter 5 kA, 8,660 V, 197 cycles, a 1 in gap, and a 23.68 in distance.
- Run the calculation with copper electrodes and record the result. The reported result was 3.5 cal/cm².
- Select stainless steel, change another input and restore it to force recalculation, then rerun the analysis. If the result remains unchanged, exit ArcPro completely and repeat the stainless-steel run in a new session.
- Verify that the refreshed stainless-steel calculation returns 4.0 cal/cm², matching the expected Table 7 value reported in the evidence.
Interpret the Gap Sensitivity and Software Behavior
The arc-gap choice materially changes the result. A 2.0 in gap produced 6.5 cal/cm² in the reported comparison, versus 3.5 cal/cm² with copper and a 1 in gap. Do not mix the 2.0 in gap with a reconstruction based on ArcPro's 1 in minimum input.
The electrode-material dropdown may not immediately invalidate the previous calculation. Treat an unchanged result after switching from copper to stainless steel as a possible stale calculation, not proof that material has no effect. Force another parameter change or restart ArcPro, then verify the output.
FAQ
What ArcPro voltage duplicates the 4.0–15.0 kV Table 7 row?
Use 8,660 V for the reported reconstruction. It is derived from the maximum range voltage as 15,000 / √3 ≈ 8,660 V, assuming ArcPro expects line-to-ground source voltage.
What arc gap and distance should I enter in ArcPro?
Enter a 1 in arc gap and 23.68 in distance to the arc. The distance is 25.68 in MAD minus twice the 1 in arc length.
Why does ArcPro stay at 3.5 cal/cm² after selecting stainless steel?
The material change may not refresh the calculation. Change and restore another parameter or restart ArcPro; the reported refreshed stainless-steel result was 4.0 cal/cm².