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Electric lake? 1

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Skogsgurra

Skogsgurra

Electrical
Mar 31, 2003
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This time of the year (when calves are born with double heads and nature in general behaves in an unpredictable manner - we call it "rotmonth" because food can't take the heat and humidity very well). This time of the year, as said, we also hear new and old urban myths. One of them is the electric lake.

This happened: One guy was swimming across a little lake when he felt a tickling in his fingers. It was in a confined area and he could swim out of and into that area. He told other people about it and now it seems that most everyone can feel it - no matter where in the lake they happen to wet their feet. So, I think that most of this is due to a "me too" effect. But the first guy seems to be sure about what he felt.

There are three major pipes terminating in the lake. Two are for snow guns (not in operation during summer) and one is the outlet from a sewer station (yes, very clean). The pipes are said to be stainless steel in the ground and some plastic material in the water.

Questions:

A Anyone had this before?

B What standard measurement techniques are there?

I plan to do a "potential map" using a DMM and a surface electrode shaped as a with cylinder about 1/4 sqm external surface (an ordinary bucket - that is). I will use an iron bar that I just let drop down to the bottom and sink into the mud as a counter-electrode. I will take readings with a high-impedance DMM (it has Gohms on one range) to see if there is anything at all. After checking that, I will switch to a relevant range (all other ranges have 10 Mohms) and then take down the readings across the "offending" part of the lake. I will use a GPS to get my coordinates.

I may also bring some fishing gear.

Comments invited. Especially if you have done anything like this before.

Read all about it on Sorry only in Swedish. But there is a picture showing a couple of guys trying to "ground" the lake. ;-)

Gunnar Englund
 
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Thanks for reminding me about the beer! Not that I really needed to be reminded about that - but better safe than sorry.

Jeff. No probs there. They can wait. Still have original paint on the house. A friend that visited last week actually brought paint and brushes. But he didn't paint... No need for enemies with such friends. :-(

Gunnar Englund
 
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I am pretty sure you can by data loggers with a gps input off the shelf.
You could mount them on a 1"x12" board about 10 feet long and let them float around the lake. Or better yet some solar cells and motor and let them cruise around the lake on their own ( like the automatic vacuume cleaners) . I am traveling or Iwould setch it up and post a conceptual design.
That would leave you in boat with the beer and making another plot of fish distribution.
 
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The beer is very important as a safety precaution for your endeavor, Gunnar, as it will help to counteract any muscle damage due to being electrocuted.
 
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You can all relax! No electric eels, no Nessie, no Godzilla. In fact, no nothing.

I followed advice from DaveScott and Smoked. I have fabricated a 2 m long pole (wood) with little hooks screwed to the ends. I also have two copper electrodes attached to insulated panel wire and attached to another couple of hooks. There is also a 0.1 microfarad/630 V capacitor to block DC. The copper electrodes hang from the hooks at the ends of the pole. I measured with a Metrahit 29S DMM. It has three voltage measurement methods; AC, combined AC/DC and DC. It is a 4 1/2 digit instrument and resolution is 10 microvolts.

Instead of measuring voltage between bottom (ground) and surface, I measured voltage gradient over the two metre distance defined by the pole.

Repeated measurements were taken across the lake. We were extra careful in the area pointed out by people that had experienced funny phenomena. The exact location is 59 20 14.2 N and 14 55 57.0 E.

We rotated the boat through all compass directions and we probed at different depths - the instrument was constantly showing less than 1 millivolt. On all ranges and with/without blocking capacitor. The same result all over the lakes.

It was only when we measured close to a pipe to one of the pumping stations that we got any indication. If we placed one of the electrodes just above the pipe and the other electrode 2 m perpendicular to the pipe we got 18 millivolts AC over two metres. A voltage gradient equal to 9 mV/m - hardly a problem for anyone. And, N.B. this is not where swimmers complain about "funny feelings". That is out in the middle of the lake where we indicated zero mV/m.

During all the measurements, we had one of the regular visitors swimming in the lake. He reported that he could feel the tingling as usual. So, we know that we did not measure when the lake was "at rest".

I close the case. There is no electricity in the "Electric Lake". What the swimmers feel is not an electric phenomenon. I start to wonder if it isn't a rural legend as opposed to an urban legend after all.




Gunnar Englund
 
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Well Google Earth certainly has horrible resolution in Sweden.. You can barely make out the lake from the trees with a lot of imagination..

Dang! Gunnar.. Not very exciting..

I'm surprised as an investigator you haven't jumped in the lake to confirm tingling. Just have someone tie a rope to your leg so they can retrieve the body efficiently.



Keith Cress
Flamin Systems, Inc.-
 
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Gunnar,

We need to help you locate some fake (rubber) eels, some flash powder, and a couple of automobile batteries. Go out on the lake (with much hoopla about how you fixed a problem in your apparatus). Set off flash powder explosion, and arc weld/fuse/melt some wiring using car batteries. Tie the eels onto the ends of your "rig" and row like hell for shore. When you show people the rig, exclaim about freshwater electric eels. Then bundle things into your car, head for home, and wait for calls from the television networks.
 
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What about that UFO that vanished over a lake in your area not so very long ago ?

What if it suddenly took off into outer space, with you, your boat, pole and little hooks all in tow ?
 
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Hello Gunnar;
This will probably expose a gap in my knowlege, but why are you just looking for AC and blocking any DC.
I would have assumed that with two identical probes any electrolytic voltages would be eliminated and also that a large variation in DC voltages may be a significant indication of something requiring more investigation.
The tingling sensation may imply an AC voltage, but another question may be, "Why does the DC cause a tingling effect that is normally associated with AC?"
I envy your boat rides. Wish I was there!
Respectfully
 
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Guys, I am disappointed.

I killed a myth. And you want it to live! Even employ cheap and dirty tricks like fake electric eels, explosions, perhaps a UFO and - on top of that have it on national television.

Hmm..

Sounds like fun, actually. OK. I will see what I can do about it. Stay tuned.

Gunnar Englund
 
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I got this clip from the paper today. There's me in the boat, a "human indicator" in the lake, head visible. I am trying to see what the volt-meter says, so removed optical aids. Yokogawa recorder can be seen to the left of me. In spite of all efforts, there is nothing to be seen. Not until we were very close to the pumping station. And there we could only read 18 millivolts over two metres.

23kwu2d.jpg




Gunnar Englund
 
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i still like the automated approach. I use to have an electrical powered duck decoy that would have worked fine. I would tie crappie jigs on it and troll around to alleviate the boredom of setting in a cold blind. I never caught anything big with it. If I had hooked a bass or a northern it would have been history.
I think I could configure a system so it would measure the fields and quack in different tones that varied with the stength of the electrical field.
 
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