So true, Ed!
Before we gutted our mountaintop station’s antiquated electrical system, we
lost a neutral. And one side of the building went to 80 volts, and the other to
160 volts.
In a miracle, I happened to be up there the moment it happened, and turned
everything off when stuff started humming ominously. We did lose some stuff on
the high side, but could have been much worse.
The local electrical provider was right on it, and helped me suss out the
issue. With the new wiring system, a whole litany of problems went away.
- 73 -
- Michael Coslo N3LI -
Frequency Coordinator, Beaver Stadium
mjc5@psu.edu
mjcn3li@nittany-arc.net
Mobile 814-404-3991
> On Mar 18, 2021, at 3:06 AM, Hare, Ed, W1RFI <w1rfi@arrl.org> wrote:
>
> No chiding, but this does represent a good example of how some RFI problems
> can represent important maintenance issues.
>
> Even the neutral is not safe. If there is a problem with a transformer
> ground and an imbalance between the loads on each of the phases, that voltage
> can rise above 0V. With the problems that you described on that pole, a
> defective ground may well be present... or not present, as the case may be. 🙂
>
> Ed
>
>
> ________________________________
> From: RFI <rfi-bounces+w1rfi=arrl.org@contesting.com> on behalf of K9MA
> <k9ma@sdellington.us>
> Sent: Thursday, March 18, 2021 1:07 AM
> To: Don Kirk <wd8dsb@gmail.com>
> Cc: RFI <rfi@contesting.com>
> Subject: Re: [RFI] Difficult power line RFI find.
>
> Hi Don,
>
> Aside from the safety issue, any time you find metal on metal contact
> near a power line, without secure bonding, you have a potential noise
> source. One example I found was a lateral guy touching a neutral wire,
> right below a single phase HV line. The electric and magnetic fields
> from the HV lines can produce currents in nearby conductors, and arcing
> where there is poor contact.
>
> 73,
>
> Scott K9MA
>
> On 3/16/2021 10:51 AM, Don Kirk wrote:
>> Hi Scott and gang,
>>
>> Thought I would provide a status report on this case, and also provide
>> a warning to others regarding something I did which I certainly don't
>> condone (I'm certainly not proud of what I did and I can't stress
>> safety enough). I hate to even admit what I did in public, but
>> thought I should mention it as it's a good example of needing to be
>> extra cautious around power poles even if you think you are safe.
>>
>> We were hoping the power pole (wooden pole) I found generating RFI
>> last week belonged to Johnson County REMC but I could not tell since
>> the pole tag number was covered up by a solar light that was likely
>> installed by a homeowner. Johnson County REMC responded to our report
>> and said the pole actually belonged to AES, so we discussed the
>> situation with our inside contact person at AES and let them know we
>> were going to get some additional data before filing a formal
>> complaint but we did send them a link to a youtube video I created
>> along with some pictures of the suspect pole. Here is a link to my
>> video documenting the suspect pole: https://youtu.be/uo5atDTo19w
>> <https://youtu.be/uo5atDTo19w>
>>
>> I went back to the pole on Sunday to get more data and someone had
>> relocated the solar light so it was no longer covering the poles tag
>> number but one of two guy wires we previously reported were wrapped
>> around the pole was now partially covering part of the pole number. I
>> used a wooden stick to push the guy wire slightly to the side (like a
>> 1/4") to make sure I could read the pole number and the RFI suddenly
>> stopped on 135 MHz which I had been monitoring by chance and the RFI
>> started right back up as soon as I stopped pushing on the guy wire.
>>
>> I then did a closer inspection of the two guy wires that were wrapped
>> around the pole and one of them (not the one I was pushing on) did
>> have a connection to the neutral line high up on the pole and neither
>> of the guys were connected to ground as both of their bottom ends were
>> just wrapped around the pole about a foot up from earth (probably due
>> to a car accident or farm implement incident, etc), and both of these
>> guys were in contact with each other due to their wrapping around the
>> pole on top of each other near the bottom of the pole. It appears
>> that my pushing on the one guy wire caused slight tension on a
>> teardrop type clip that was on the top end of the guy wire I was
>> pushing and this teardrop clip (almost like a D ring) rests
>> (straddles) on a through bolt assembly high on the pole which acts as
>> the anchor point for the guy. Note: At least the neutral line on this
>> pole is located below the hot (live) line so little chance for the guy
>> lines to come in contact with the hot (live) line even though they're
>> not properly secured.
>>
>> I then did similar tests on 24.98 MHz, 1.8 MHz, and 1710 KHz, and the
>> RFI stopped each time slight pressure was applied to the guy line that
>> was covering the pole tag number. I actually set up HF gear a good
>> distance from the pole, had my Iphone camera recording the HF gear
>> while I ran back to the pole to push slightly on the guy wire with my
>> wooden stick.
>>
>> I then contacted our inside person at AES and told them (admitted)
>> what I had done and that I was now concerned this pole was not just an
>> RFI issue but also a potential electrical safety issue since the guy
>> wires were not connected to earth at the bottom of the pole while one
>> of them is also connected to the neutral line up on the pole and the
>> guys are also not properly secured even though they are are wrapped
>> around the pole (better to remove them versus have them like they
>> currently are). Our AES contact person then said they had actually
>> already responded to the area on Friday after our initial informal
>> report to them and had identified a couple poles generating RFI in the
>> area which included the one I had identified, and they had already
>> issued a rush work order to fix the poles.
>>
>> Note: one of the two guy wires might have actually been a steel strand
>> for supporting telephone wire in the past, I really have no idea.
>>
>> I did take what I thought was reasonable precaution using my wooden
>> stick, but you can never be safe enough in my opinion and no reason to
>> take the risk.
>>
>> Bottom line (no pun intended) is that you should not touch anything on
>> a power pole even if you think you are totally safe with what you are
>> doing. This is just my opinion, but I think it's sound advice which I
>> know has been mentioned previously (I know hitting a pole with a
>> hammer has been mentioned as a no no in the past, etc). It took me a
>> day to work up the courage to post this story, and please don't
>> chastise me.
>>
>> 73,
>> Don (wd8dsb)
>>
>> On Wed, Mar 10, 2021 at 3:53 PM K9MA <k9ma@sdellington.us
>> <mailto:k9ma@sdellington.us>> wrote:
>>
>> If your local utility is cooperative, they may share with you maps of
>> their distribution lines.
>>
>> 73,
>> Scott K9MA
>>
>>
>> On 3/10/2021 11:18 AM, Don Kirk wrote:
>>> Hi Eddie,
>>>
>>> Thanks for sharing your very similar story, and very interesting
>> based on
>>> the configuration of lines I was dealing with. As a matter of
>> fact I was
>>> using Google Earth this morning to look at the lines I was
>> dealing with
>>> yesterday and wish I knew more about power distribution to better
>>> understand all the hardware. Nevertheless I too was dealing
>> with parallel
>>> running lines in the area where I found the suspect pole. One
>> set of
>>> lines which appear to be 3 phase run the full length of the road
>> on the
>>> North side of the street, and the suspect pole I located was
>> also on the
>>> North side of the street but it was fed by parallel running
>> lines on the
>>> South side of the street and I don't believe the South side of
>> the street
>>> lines are 3 phase. The suspect pole then fed some additional
>> poles running
>>> up a very long driveway to a house set way back off the road.
>> The lines
>>> that my antennas always pointed perpendicular to were the 3
>> phase lines on
>>> the North side of the street which were not physically connected
>> to the
>>> lines with the suspect pole as far as I can tell, and if my
>> theory is
>>> correct that would say the RFI I was getting induced into the 3
>> phase lines
>>> by the lines running on the South side of the street that were
>> connected to
>>> my suspect pole.
>>>
>>> We shall see, but boy my story sounds very familiar with yours
>> as far as
>>> parallel running lines with a cross over to my suspect pole
>> right under
>>> what I'm calling the 3 phase lines that run the full length of
>> the street
>>> East/West.
>>>
>>> Thanks,
>>> Don (wd8dsb)
>>>
>>> On Wed, Mar 10, 2021 at 10:49 AM EDWARDS, EDDIE J
>> <eedwards@oppd.com <mailto:eedwards@oppd.com>> wrote:
>>>
>>>> Don,
>>>>
>>>> Great story! Thanks for sharing.
>>>>
>>>> We had a very similar experience near my QTH several years ago
>> affecting
>>>> my home location and also another ham on about a mile north of
>> me. Only
>>>> difference was it was strong on low bands, and it was strongest
>> on 80
>>>> meters at S9+, and probably on 160meters too but neither of us
>> had antennas
>>>> for 160 meter back then. The other ham is a mile north of me
>> and we are
>>>> both in nearly a north-south line perpendicular to a 161 KV
>> transmission
>>>> line.
>>>>
>>>> Also, I should mention that I work in the utility department
>> that is
>>>> responsible for tracking power-line noise although it's our
>> technicians
>>>> that do these RFI cases regularly. I only get involve in
>> problem case, or
>>>> in this case when I am affected at my home shack.
>>>>
>>>> It appeared to be coming from the direction of the161KV line
>> that runs
>>>> East-West; however, when the tech was using our new HF loops we
>> had the
>>>> same perpendicular indications no matter which direction we
>> traveled. It
>>>> was staying strong for 1 to 2 miles in each direction before
>> beginning to
>>>> fade. Our mistake was to stay too focused on using HF freqs
>> for tracking
>>>> that day, but we were also initially confused by the southwest
>> direction we
>>>> got at the ham's QTH 1.5 miles north of the 161KV line. We
>> only switched
>>>> to VHF/UHF in the area to the southwest finding nothing there.
>>>>
>>>> We unknowingly drove past the actual source directly south of
>> both ham's
>>>> QTHes a few times not realizing this before ending our search
>> at the end of
>>>> the work day (techs are union, no OT on RFI cases).
>>>>
>>>> The actual source turned out to be a distribution pole on a
>> 13.8KV line
>>>> that ran parallel with the 161KV line for a short distance as
>> it crossed
>>>> over the main street perpendicular to both lines to reach a
>> couple houses
>>>> on that street. The RFI source was apparently causing
>> induction into the
>>>> 161KV line from the shorter 13.8KV line.
>>>>
>>>> We never had to track the source down to fix it. On my way
>> home from the
>>>> office that same day, as I drove toward the 161KV line while
>> listening to a
>>>> blank spot on my AM radio, it appeared the noise was already
>> gone! As I
>>>> approached the 161KV line I see a couple of our utility trucks
>> working to
>>>> install a new pole replacing one of the old poles on the line
>> that ran
>>>> parallel under the 161KV line. Since the noise never returned,
>> I assume
>>>> the old pole that was replaced was our source pole.
>>>>
>>>> Some days you just get lucky!
>>>>
>>>> 73, de ed -K0iL
>>>>
>>>> -----Original Message-----
>>>> From: RFI <rfi-bounces+eedwards=oppd.com@contesting.com
>> <mailto:oppd.com@contesting.com>> On Behalf Of Don
>>>> Kirk
>>>> Sent: Tuesday, March 9, 2021 6:27 PM
>>>> To: RFI <rfi@contesting.com <mailto:rfi@contesting.com>>
>>>> Subject: [RFI] Difficult power line RFI find.
>>>>
>>>> Just thought I should share something that was a first for me when
>>>> tracking down power line RFI and man it was frustrating, and I
>> have tracked
>>>> down a lot of powerline RFI.
>>>>
>>>> I noticed some weak RFI at Dans (KB9AX) on 160 meters earlier
>> this year
>>>> but did not have time to track it down. Dan also complained
>> about the RFI
>>>> and he mentioned this week that it was not strong but had
>> become very
>>>> consistent. It definitely looked and sounded like powerline
>> noise (120 Hz
>>>> spikes observed on audio scope and SDR receiver, etc.) ---snip---
>>>>
>>>>
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>>
>>
>> --
>> Scott K9MA
>>
>> k9ma@sdellington.us <mailto:k9ma@sdellington.us>
>>
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>>
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