This guy's thinking is going to get someone killed...
From Wikipedia:
As an example of the energy released in an arc flash incident, in a single phase-to-phase fault on a 480 V system with 20,000 amps of fault current, the resulting power is 9.6 MW. If the fault lasts for 10 cycles at 60 Hz, the resulting energy would be 1600 kilojoules. For comparison, TNT releases 2,175 J/g or more when detonated.
Thus, this fault energy is equivalent to 380 grams (approximately 0.8 pounds) of TNT.
FYI, a WW2 hand grenade contains 57 grams of TNT.
I wonder how safe a soldier would have felt behind a homemade piece of Lexan.
