Vincent B. wrote:
That's only an electrical arc when you open/close a circuit under load. That's not an arc flash. It cannot develop into an arc flash (not because it's 120 VAC, but because you have the load in series with the arc).
Then how come I can strike an arc with a welder at far less voltage than that, and if I do any significant amount of arc welding without eye or skin protection, I get a very nasty "sun burn", itching/stinging eyes, and potentially even corneal damage? To say nothing of the burns I can get from the pure radiative heat from the arc welding process?
"Arc flash" is a combination of physical phenomena of the effect of the light and radiation released from an electric arc. Arc blast is generally considered the concussive force, shrapnel, and hot vapors/plasma that is released though obviously this is not a hard and fast rule.
You can get an arc in a hard vacuum, too. Don't even need air to be present. This is the limiting factor on the reason why you don't find vacuum interrupters much above 600 A continuous duty.