Cable Tray Arc Flash

jmellc

Senior Member
Location
Durham, NC
Occupation
Facility Maintenance Tech. Licensed Electrician
I had some fireworks yesterday. Was pulling cable in a cable tray. Used a stick of 3/4 EMT to fish awkward portions. Had a helper & showing him the procedure. We finished at one one & I lifted the conduit as I was telling him something. Suddenly got a huge flash & bang. An old parallel feeder had been discontinued from nearby equipment & laid in the tray, taped up. Not the best or right way to do that but I’ve seen it before. A closer look showed that one leg had not been disconnected in the switchgear by the contractor awhile back. Wire was poorly taped as well & I hit hot & ground for a 277V/800amp flash.
I have generally used PVC pipe for such a task but also what was available. I will now use PVC only and test any similar cables I see. We searched today & found a few others, though not live.
Either someone forgot part of his procedure or got pulled in the middle of the job.
 
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