My utility (or myself and a few other protection engineers at my utility) decide to utilize ArcPro for our medium and high voltage arc flash analysis. After reviewing the literature that came with ArcPro I just realized ArcPro was only empirically verified up to an arc gap of 20 inches. If you apply a typical minimum air gap to provide sufficient insulation between two live parts, ArcPro real is limited to approximately 70Kv. I know the NESC tables go beyond 70Kv, and it is suggested that ArcPro was used to create the tables (someone decided to ignore the software’s limitation). Has anyone else used ArcPro for an arc gap beyond 20 inches? And if so do you feel the results were reasonable?

Ignore my above statement

You can ignore my above statement. I was originally looking at a more conservative standard to estimate the minimum distance between two live parts to avoid a flashover. I also assumed the worst case scenario and was applying the phase to phase voltage instead of the phase to ground voltage that was used to develop the NESC tables. If you apply the same criteria that was employed to develop the NESC tables (IEEE std 4 – 1995), ArcPro’s limitation is well beyond 70Kv: (345Kv / sqr(3) )/ 10Kv => 19.9 inches