[RFI] Metal Pole vs Wood Pole

[EDWARDS, EDDIE J]

I can confirm Mike Martin's assessment regarding metal poles, or at least with the problem we found from an all metal cross-arm mounted on a wood pole.  Can't find the document on the cross-arm's mfr and model now, but it is a known problem with arcing that leaves black charring in several places along the entire cross arm wherever it had hardware connections.  The arcing eventually causes the metal arm to fail confirmed by many other utilities where it has been used.  

The RFI could be heard for a few blocks in every direction from the pole which was located in a commercial zone immediately next to the Salvation Army buildings which had an Amateur Radio station installed in one of their buildings.  This made it difficult to narrow down the source by our RFI technicians who spent many hours working this case before they narrowed it down to the pole with a metal cross arm.  The techs misidentified several other nearby wood poles with noise that were not causing the RFI to the SA's ham station before getting the onion pealed down to the metal cross arm.  

A line-tech troubleshooter made us aware of the flawed design of the metal cross arms and recommended replacing the whole metal arm with a wood cross arm.  The next problem delaying resolution was scheduling an outage for the entire commercial zone on that circuit and not impacting other nearby company's, but that's a whole other story.  

73, de ed -K0iL
Ed Edwards, P.E. 

-----Original Message-----
From: RFI <rfi-bounces at contesting.com> On Behalf Of Michael Martin

Hello Charles,
That's a good consideration. Most power line interference sources are created buy loose connections due to the wood shrinkage and corrosion between the hardware on the poles. Without the shrinkage a lot of that hardware wouldn't be an issue. so it's safe to say that a steel pole will not have as many problems as a wood pole. However, if the noise is on a steel structure the noise will radiate much stronger close to the structure then it would if it were a wood pole. The steel will act as a radiator for the noise and make the noise much stronger when you're close to the pole. At a distance away from the pole the noise would be relatively the same as if it were on a wood pole. 
The good thing is they're replacing the whole structure that your noise is on.
Let's hope during the process they don't start other noises for you by shaking up 10 spans of wire and poles in each direction.

On Dec 4, 2019, 4:52 PM, at 4:52 PM, Charles Plunk <af4o at twc.com> wrote:
>Does it make any difference as to risk of future rfi whether the pole 
>is metal or wood (does hardware loosen more often on wood poles)? Just 
>curious as the new poles they install most or all seem to be metal.