Years ago, I was in the room when there was an arc flash/blast event about 30 feet away.
I was sitting at a print table when an electrician either grounded or shorted phase to phase, a 600 Volt bus in an MCC.
I looked up and saw two men standing frozen in place, out on their feet and one man down with his coveralls smouldering.
I stood up, ran over and slapped out the embers on his coveralls. I thought that he was dead, but as I was slapping his leg to extinguish the embers, he started to moan and groan. About that time, the other two men, who had been about three or four feet from the blast center, started to respond.
While my response time could be measured in seconds, it was well past two seconds before anyone but myself moved.
While the MCC contained most of the flash, we found several blank covers from the MCC across the room. Thankfully no-one was hit by them.
Had the arc persisted rather than being cleared instantaneously, no-one was going anywhere under their own power for something more than 2 seconds.
Anecdotal, yes, but you had to be there.
David Beach said:
I don't use the 2 second "rule", it's asinine. The only way it could possibly matter is if you get blown out of the danger zone in less than 2 seconds.
I agree completely.
The worker had been kneeling in front of the MCC. After the blast, he was stretched out on the floor. His feet were close to the MCC but his torso was farther from the MCC than the two "frozen in place" workers who had been standing beside him.
Bill
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Ohm's law
Not just a good idea;
It's the LAW!