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The Arc Flash Incident

This was a very close call and if my timing would have been off by for more than 3 sec I wouldn’t be posting about ittoday. The power generation plant I took care of had two out of the three of these switchgear units built by ABB. They were never put into production due to problems they were having keeping the SF6 gas in them used to suppress arcing.

They made several attempts to rectify the problem to no avail. Basically management dropped the ball on that one and I had no choice but continue using the gear even though they were aware of the safety risks It was a 13Kv system which is highly dangerous even on a good day with good equipment. Neither did they supply the personal gear usually required to work on high voltage systems. In retrospect I should have went thru the legal channels with OSHA, but it would have made quite the stink. The company usually found a way around most of OSHA’s guidelines so I didn’t even bother and needed the job.

I had to roll the gear in and out by hand and every time those knives were opened or closed without SF6 in the switch chambers we were pushing it.

The oilfield had miles of the 13Kv grid and trees threw the lines and other problems were quite common, nothing but hills and trees. On one occasion the field electricians had problems during the night and still hadn’t identified the problem that morning when I showed up. They’d already opened and closed the gear several times and I was next to do it,  they watched the shots on the poles outside for signs of trouble. I didn’t know just how close the grim reaper and I were getting at that point.

I was always pretty nervous around the stuff when they had line problems, so zi was tense to say the least. When I rolled the knives in I heard what I thought was on of the HV fuses blow, and instantly headed for the door out of the building. I covered the 15 foot or so as fast as possible and just as I reached the doorway the gear exploded. The blast tossed me face down outside in the rocks. If I’d have hesitated 2 or 3 sec the arc flash would have caught me full on in the face. My instincts proved true that day for sure.

The heavy gauge cabinet top just folded up around the 4″ conduit, blew the doors off and puffed the whole thing like a toad frog.

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I was head level with the top of the cabinet when I rolled the knives in (pic on the right). The arc flash alone would have killed me if the doors blowing off hadn’t. Close call for sure.

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This is whats was left of the switch chamber. The shrapnel all missed me.

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