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MIND YOUR SAFETY by Dave Smith |
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A few extra minutes for your life: Daniel’s decision
I’ve known Daniel (not his real name) for several years; he had been a journeyman for about 25 years, and had his own one-man contracting business. Then he had an accident, and quite a few weeks passed before I saw him again. When I did, a body wrap was covering his torso.
It turns out he had been working on a 480V electrical panel with a local three-phase disconnect, which he turned Off before opening the panel and getting to work. When he put his screwdriver into the panel, an explosion occurred.
(This is common with older disconnects: one blade stayed in because the mechanism was broken. Sometimes you can actually feel this as you are operating the handle. Perhaps the person who last closed the disconnect felt or heard something strange but never thought to check it out further.)
Regardless, Daniel paid the price for this breakdown. When his screwdriver hit the live phase, he created a short circuit to ground that quickly built from line to ground, line to line to ground, and eventually all three phases to ground.
As with any arc flash accident, it was all over in a split second. All that was left of Daniel’s shirt were the cuffs and the collar—everything else was burned right off his body. Luckily, his face was spared a direct blast of hot plasma as it blew out of the panel because it was positioned a little lower on the wall.
I visited Daniel regularly after the accident (he was in that body wrap for about six months) and asked him about the pain. Burn pains are terrible. Take the sensation you get when you burn your finger with a match, lighter or stove element, then magnify it a thousand times across your entire body. Daniel said the doctors were finally able to get his pain under control, but it was the nights that he found most difficult as he tried to find a comfortable position in which to sleep. He was in continual agony for months.
Eventually, I grilled Daniel about the accident; specifically, I wondered why he had not done a voltage check. He was clearly embarrassed when he admitted that his meter had been in his toolbox, and he couldn’t be bothered to get it, so he reasoned that, well, if the disconnect is Off, then so should the power to the panel.
Daniel made a devastating assumption that cost him dearly (and we all know what happens when you “ass-ume”)—first the torturous pain, then the loss of income as a self-employed contractor. With no compensatory insurance to get him through this rough period, he was forced to return to work a lot sooner than he should have. Though still in pain, he was out there working and trying to put bread on the table. Normally a very calm guy, the constant pain and financial pressures made Daniel pretty short-tempered, and his family got the brunt of it. It was a difficult time for all of them.
This is the rational behind NFPA 70E, Rule 120.1(5), which requires a contact voltage measurement before starting work: simply too many accidents have occurred because people assumed an electrical circuit was deenergized when, in fact, it was not.
The difficulty with people is that we’re always in a hurry; our meters “are way over there in the toolbox” or “out in the truck”, and we make a bad judgement call. Forcing ourselves to perform a voltage check every single time is difficult; we’d rather take a short cut here and there. However, skipping a voltage reading is not a short cut you want to take. Neglecting to verify that a piece of equipment is truly deenergized risks both your life and your livelihood.
Don’t be hasty: take a few extra minutes, get your meter and save your life.
Until next time, be ready, be careful and be safe.
Mind Your Safety is a monthly column authored by Dave Smith of Canada Training Group for Electrical Business magazine.
Reprinting of this article is allowed for the intent of furthering safety awareness, with the requirement
that articles(s) are used in their entirety and authorship is duly credited to Dave Smith,
Canada Training Group and Electrical Business magazine.
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