How far will OH lines carrying 7.2 kV arc? I have a technical reference that states it will arc 3/8" per kV, but an employee challenged my position, stating that distance could be increased by such factors as blowing dust, rain/snow, and magnesium chloride from DOT snow plows. We know the OSHA rule od 10 feet for lines of 50 kV, with multipliers for voltages above that, but I wish to know what your experience tells you.