I reading this months EC&M magazine and was struck by
this story. It tells of an electrician who died from the effects of an arc-blast caused while attempting to lock-out a piece of 4,160 volt switchgear.
Apparently the electrician was using a meter that failed to clearly specify that the dislay was showing "kilovolts" instead of "volts." The electrician read a phase-to-ground measurement of "2.4" and assumed volts. He then attempted to make a hard ground to the energized point and caused an arc-flash.
Consider:
- The victims first two attempts to test for voltage failed.
- He then chose to employ a meter which he was apparently unfamiliar with (he did not understand what the display was reading).
- After getting different readings at different points, he didn't attempt to resolve that discrepancy or test the meter on a known energized terminal.
- The electrician failed to recognise that 2.4 would be the correct phase-to-ground reading in kilovolts for that system.
- After only a single effective test with a single, unfamiliar meter, he assumed the gear was de-energized.
- The electrician was not wearing any sort of arc flash protection.
- He apparently did not understand the layout of that piece of switchgear and couldn't tell what terminals may be energized or why.
While everybody is fallable and everybody makes mistakes, given all the above, it seems to me that the failure of the meter to display "kilovolts" is overshadowed by what seems like an extremely cavalier attitude by somebody who was prepairing to intentionally ground a conductor that could be energized at four-thousand volts.
I'd be interested to hear some more experienced opinions weigh in on this.
-John
