To answer my own question I am guessing that dirt around the fused
disconnects insulator allowing enough flow to arc to ground. And the
crepe myrtle with its moist branch this time of year and deep roots
provided a better ground than the util ground thus the arc.
On 5/24/21 2:13 PM, Charles Plunk wrote:
If you have been following my latest saga, I have a 3 phase pole at
the corner of my back yard and another (both wood) in the front yard
topped with 3x 7.2kv lines. Weeks ago I located an arc on the back
pole through the usually methods and finally seeing it with binoculars
in the dark. Power co fixed, it was the ground wire stapled to the
pole to close to a bolt which mounts the fused disconnect. They simply
moved the wire away and re-stapled. It is gone.
I had a 2nd arc on that pole but on the opposite side. It has all but
disappeared on its own with higher humidity. I suspect it will return
in the fall but ultrasonic tended to site on another part of the same
ground wire.
Fast forward to 2 days ago, I begin to hear another strong arc. But
this one is on the front yard pole. There is a crepe myrtle (~20-25'
high) that has begun to grow around the pole but nowhere near the top
3 phase. Using my ultrasonic I heard it best lower on the pole where
the crepe myrtle is around and probably touching the ground wire.
My question is, why is a wire at ground potential arcing to hardware
insulated from the 7.2kv or to a crepe myrtle on either pole? Those
ground wires go all the way to ground stapled to the pole uninsulated
where anyone can touch them. I am glad to locate these rfi sources but
trying to wrap my head around why?
73
Chuck
W4NBO
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