Any two conductors anywhere near HV line can cause noise if they are not either
well insulated from each other or securely bonded together. The field from the
HV wires induces voltage in the conductor, which can cause an arc. In my
experience, this is by far the most common cause of power line noise.
73,
Scott K9MA
----------
Scott Ellington
--- via iPad
> On May 24, 2021, at 2:13 PM, Charles Plunk <af4o@twc.com> 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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