Trouble With Power Lines?

December 18, 2003

i went after a cache today that was located under some major power lines. my gpsr went totally nuts. i had a clear sky, no trees, and my e-trex said it was accurate to 20 feet. it was at least 200 feet off and it didn't know what direction i was heading. has any one else had this problem?

5k · December 18, 2003

I've had this happen. I was searching for a cache very near a major intersection with crisscrossing powerlines above. No matter where I went, the GPS pointed me to a different side of the street. I tried to triangulate, but it was hopeless. I couldn't get a good reading. I ended up logging a no-find. Others have stated that they had no problems at all at that location.

From a physics standpoint, there's good reason. Those powerlines are surrounded by fairly strong magnetic and electric fields. I imagine the signals from the satellites aren't completely unaffected when nearby, although I don't have any first-hand knowledge.

Jamie

December 18, 2003

Yeah I have similar probblems as well around power lines and then other times none at all

December 18, 2003

And then there could be very small arcs happening between the power lines and ground (defeating the insulators or the like if it is damp.) Electrical interference plays heck with radio receivers. -Ken

December 18, 2003

Tower to tower electrical power lines (conductors) in many cases carry very large amounts of current and therefore can throw out an enormous amount of RF interference. Of course most people know this, but what they may not realise is that varying weather conditions and other circumstances can greatly alter the amount of interference emitted.

Have you ever been searching for a geocache under high tension lines and NOT had any problems. This will be because demand on the lines was low at the time and the current passing was very low. Just because they are high voltage lines doesn't mean they are carrying high voltage all the time. In fact, a lot of the time the lines may not be being used at all. Conversely, if the lines are in high demand at the time, you can kiss your sat' signals goodbye. After a long dry spell followed by rain the lines can often arc at the insulators and this can also cause massive interference even if you are nowhere near being underneath the lines.

In Australia, we often have very long spells of dry so when it finally rains we get a very nice green and blue light show courtesy of the wet dirt/mud build up on the lines.

So, if it's a very hot or very cold business day, chances are the demand for power is greatest so the interference will be greatest.

Remember, electricity is a supply on demand only resource, it cannot be stored. A pleasant Sunday afternoon, not too hot and not too cold would probably be the best time to search under powerlines.

Also, stay away from the tower during storms. The two thin wires at the top of a power transmission set are there for one purpose only, to attract lightning. They earth any strikes to the nearest tower.

Just for your info.

Edited December 18, 2003 by The 2 Dogs

3.5k · December 18, 2003

Very interesting 2 Dogs!

I've always assumed power lines are constantly coursing with energy. :lol:

Thanks for the info!

1.1k · December 18, 2003

On a positive note they block some of the voices in my head and stop the Venusians from reading my thoughts........all three of them.

December 18, 2003

Tower to tower electrical power lines (conductors) in many cases carry very large amounts of current and therefore can throw out an enormous amount of RF interference. Of course most people know this, but what they may not realise is that varying weather conditions and other circumstances can greatly alter the amount of interference emitted.

Have you ever been searching for a geocache under high tension lines and NOT had any problems. This will be because demand on the lines was low at the time and the current passing was very low. Just because they are high voltage lines doesn't mean they are carrying high voltage all the time. In fact, a lot of the time the lines may not be being used at all. Conversely, if the lines are in high demand at the time, you can kiss your sat' signals goodbye. After a long dry spell followed by rain the lines can often arc at the insulators and this can also cause massive interference even if you are nowhere near being underneath the lines.

In Australia, we often have very long spells of dry so when it finally rains we get a very nice green and blue light show courtesy of the wet dirt/mud build up on the lines.

So, if it's a very hot or very cold business day, chances are the demand for power is greatest so the interference will be greatest.

Remember, electricity is a supply on demand only resource, it cannot be stored. A pleasant Sunday afternoon, not too hot and not too cold would probably be the best time to search under powerlines.

Also, stay away from the tower during storms. The two thin wires at the top of a power transmission set are there for one purpose only, to attract lightning. They earth any strikes to the nearest tower.

Just for your info.

Maybe they turn the electricity off at 10:00PM in Australia, but that's not the case around here. I've never come across an un-energized high-voltage line unless it is under construction or maintenance. Even under maintenance, they might be working on the lines "hot".

The voltage isn't going to change (other than what naturally happens in AC). If it's a 5KV line, it's always going to be near that number. If it isn't, there's a major problem.

Current is the only thing that should vary in the line. Even so, you want to keep the current as low as possible to minimize power loss in transport. That's why the voltage was stepped up in the first place.

Under normal operating conditions, regardless of how much current, or even voltage, the frequency is always going to be 60Hz (Maybe 50Hz in some parts of the world). This isn't anywhere near the sat frequencies. Arcing might cause some wide-band disruption, but that's an unusual condition. If the power lines are throwing off a bunch of wide-band noise, radio operators and/or the FCC will be all over their case.

I've been under power lines many times, and large power generating stations, and have never encountered a GPS problem. Any GPS reception problem is more likely due do things like multi-path coming off the large tower structures.

George

4.8k · December 18, 2003

I've never encountered GPS problems, but there is a store parking lot near my home that is close to some large power lines, several radio towers, and a TV tower. I'm not sure which is causing it, but whenever I park there, my car remote will not work. Maybe I'll take my GPS with me next time and see what happens.

2k · December 18, 2003

Any GPS reception problem is more likely due do things like multi-path coming off the large tower structures.

We have a winner! :lol:

I've had more problems with caches next to cliffs that "shadow" reception than power lines.

This isn't anywhere near the sat frequencies.

1575.42 MHz primary

1227.60 MHz

1176.45 MHz

December 18, 2003

I found this cache Andrew's Awesome Cache when it was raining and the power lines were crackling as I hike up the hill under them. It was eerie but the GPS (at that time I used a Garmin 12XL) had no problems. I was pleasantly surprised :lol: .

I have no experience with large power lines in Alaska ... yet.

Northern Trekker

December 18, 2003

George nailed it. It's the towers, not the lines or any current passing through them. It's the signals getting reflected and bounced by the structure of the tower, not RF interference.

If you lines are dead, you have a much bigger problem. I should know, I live in First Energy territory. They're the guys responsible for blacking out the entire northeast USA.

December 18, 2003

A lot of scientists and electrical engineers want to deny this, but the biological evidence is irrefutable.

The vegetation that grow underneath power transmission lines has many times more cellular mutations, anomalous shapes, sterile seed, and reproductive difficulties than the identical plants just a few yards away. Oddly enough, the plants grow faster, taller, and larger, but are misshapen and mutated.

Kinda makes you wonder about transmission lines going through the middle of a residential neighborhood or over a school playground. Then again, it may explain some of the kids I know...

December 18, 2003

A lot of scientists and electrical engineers want to deny this, but the biological evidence is irrefutable.

The vegetation that grow underneath power transmission lines has many times more cellular mutations, anomalous shapes, sterile seed, and reproductive difficulties than the identical plants just a few yards away. Oddly enough, the plants grow faster, taller, and larger, but are misshapen and mutated.

Kinda makes you wonder about transmission lines going through the middle of a residential neighborhood or over a school playground. Then again, it may explain some of the kids I know...

I've seen the same arguments about plant life in crop circles.

Study this link for more info about power lines and health: http://www.mcw.edu/gcrc/cop/powerlines-cancer-FAQ/toc.html

George

December 19, 2003

Maybe they turn the electricity off at 10:00PM in Australia, but that's not the case around here. I've never come across an un-energized high-voltage line unless it is under construction or maintenance. Even under maintenance, they might be working on the lines "hot".

The voltage isn't going to change (other than what naturally happens in AC). If it's a 5KV line, it's always going to be near that number. If it isn't, there's a major problem.

Current is the only thing that should vary in the line. Even so, you want to keep the current as low as possible to minimize power loss in transport. That's why the voltage was stepped up in the first place.

Under normal operating conditions, regardless of how much current, or even voltage, the frequency is always going to be 60Hz (Maybe 50Hz in some parts of the world). This isn't anywhere near the sat frequencies. Arcing might cause some wide-band disruption, but that's an unusual condition. If the power lines are throwing off a bunch of wide-band noise, radio operators and/or the FCC will be all over their case.

Maybe you guys need to go back and read my previous post again. At no stage did I say that the number of Volts in the power lines are altered. I only made reference to variations of CURRENT on variation of demand, however I did state that the high voltage lines may be ON or OFF.

For your information major electricity transfers in this country are usually done at 330KV or 132KV.

Where our electricity system my vary from yours over there, is that we feed our grids from several potential (and completely independent) sources and 'share the load' so to speak. You say that in your country it would never occur for transmission lines to be idle. Perhaps your options are too limited to allow 'rest' for some generation resources, this might explain the ridiculous situation where it's possible for your largest cities to be entirely blacked out, and you authorities unable to rectify the situation in an instant.

There are many transfer/backup lines criss crossing our country. Most will never be de-energised during their useful life but many others are only there as backup.

In reference to RF interference, to suggest that you could operate ANY radio receiving device directly under lines carrying 33,000 Volts of AC electricity. (With the amount of inductance and RF energy being produced) and still not have any receiving problems, seems absurd. How far are you away from these lines when directly under them....maybe 15 metres? At that power, it would just about put you in the inductance field, but of course you guys will know better, so I'll throw it back over to you.

Edited December 19, 2003 by The 2 Dogs

December 19, 2003

Just because they are high voltage lines doesn't mean they are carrying high voltage all the time. In fact, a lot of the time the lines may not be being used at all.

Your above statements don't imply that there is a variance of voltage? I guess I'm going to have to take another critical reading class back at school or something. :mad:

I believe what you -> thought <- you were typing was that the current is not necessarily high all the time. To this, I'll agree. And yes, multipath probably does have a lot to do with the interference...

December 19, 2003

In reference to RF interference, to suggest that you could operate ANY radio receiving device directly under lines carrying 33,000 Volts of AC electricity. (With the amount of inductance and RF energy being produced) and still not have any receiving problems, seems absurd. How far are you away from these lines when directly under them....maybe 15 metres? At that power, it would just about put you in the inductance field, but of course you guys will know better, so I'll throw it back over to you.

Since it's so far off topic, I'll skip the mis-information about electrical grids.

But what's so absurd about operating "ANY radio receiving device" under high voltage power lines? I used to work at a large power plant, and had to drive miles under and near the distribution lines. I don't recall ever having a reception problem with my car radio. I spent a lot of time around the main transformer while talking on a 2-way radio without any problems.

Just because high voltages and/or currents are involved, it doesn't necessarily black out radio communications. If the power company is generating noise in the radio bands, they're pretty much obliged to fix it.

George

24.7k · December 19, 2003

I had a cache under tree cover, at the base of a rock ledge, below a substation. People complained about accuracy.

December 19, 2003

This reminds me of the "Barenaked Ladies" song, "Light Up My Room".

It starts off something like this:

"A Hydrofield cuts through my neighborhood.

Somehow that always just makes me feel good.

I can put a spare bulb in my hand

and light up my yard."

:mad:

December 19, 2003

EVERYBODY!!!

...Late at night when the wires in the walls

Sing in tune with the din of the falls

I'm conducting it all while I sleep

To light this whole town

If you question what I would do

To get over and be with you

Lift you up over everything

To light up my room

There's a shopping cart in the ravine

The foam on the creek is like pop and ice cream

A field full of tires that is always on fire

To light my way home

There are luxuries we can't afford

But in our house we never get bored

We can dance to the radio station

That plays in our teeth

If you question what I would do

To get over and be with you

Lift you up over everything

To light up my room

A Hydro-field cuts through my neighborhood

Somehow that always just made me feel good

I can put a spare bulb in my hand

And light up my yard

Light up my yard

Lights in my yard

Light up my yard

December 19, 2003

HA! Threre you have it!

"I can put a spare bulb in my hand

and light up my yard"

and,

"But in our house we never get bored

We can dance to the radio station

That plays in our teeth"

"Bare Naked" proof that power lines don't knock out the radio spectrum! :mad:

George

P.S. If you haven't heard this song, it's worth listening to. Kind of a nice ballad that sounds very normal....until you start paying attention to the words.

Edited December 19, 2003 by nincehelser

5k · December 19, 2003

"But in our house we never get bored
We can dance to the radio station

That plays in our teeth"

An obvious (and amusing) reference to the Partridge Family.

Jamie

December 19, 2003

"But in our house we never get bored
We can dance to the radio station

That plays in our teeth"

An obvious (and amusing) reference to the Partridge Family.

Jamie

I was thinking it was a reference to Lucille Ball and her spy work that her fillings did for the Government.

Check it I'm not making this up, she actually did claim this to be fact on a talk show

really.

Edited December 19, 2003 by mogolloyd

2.7k · December 19, 2003

I was thinking it was a reference to Lucille Ball and her spy work that her fillings did for the Government.

Check it I'm not making this up, she actually did claim this to be fact on a talk show

*raises hand*

I saw that too. Very.... odd.

December 29, 2003

Resistance to radio interference is a product of the receiver. What i mean is that the reciever needs to have filters and shielding built into it to resist errant radio frequency (RF) noise. Certainly the older guys on here remember hearing a bad sparkplug wire buzzing through their car radio. Something you don't hear much of anymore because the filtering and sheilding in car radios has greatly improved over the years. The same can be said about TV sets. Turning on the microwave or the blender doesn't usually skew the picture on your TV anymore. I'm not sure how much sheilding is built into a GPS receiver. I have been working on a multi part cache for a while and one part is under a 69KV power line. My GPSr goes nuts under it.......every time. In the U.S. AC power is transmitted at 60hz, but that has nothing to do with errant radio frequencies that may be created from things like atmosheric conditions and a host of other things.

2k · December 29, 2003

Exactly what I ran into when I thought it would be cool to build a re-broadcast antenna for my car. The ceramic filters cost way more than the amplifier and patch antenna. In the end it is cheaper to buy than build.

2.6k · December 30, 2003

OK I'm not knocking the Etrex line, But I think this has come up more then once or twice and it usually starts out my Etrex went goofy under power lines and was off by a long ways. Anyone else out there remember other topics along this theme?????.

Personally neither brand of my GPS's has had any problem under power lines, but deep narrow canyons oh yes.

December 30, 2003

interesting thread....

i'm not an electrical engineer, or a radio freq engineer either, but i do work with microwave radio systems all day and i know that electromagnetic fields will interfere with the operation of some of the systems. on our preliminary site surveys we need to document any areas where the indoor equipment, antennas, or cabling could be in the area of high voltage lines or equipment, including elevator rooms. i know of one case where our equipment was interferring with the elevator controls in a building and a case we have right now where the rf coax cable runs through an elevator equipment penthouse and we have recurring problems during the day-when the motors are running, and none at night-when the elevators are sitting still.

ps, the radio in my 86 vw crackles with noise when i drive under local powerlines, never mind the big boys. at intersections with lots of lines, its unusable.

electro mag fields will mess up reception on some radios and receivers.

just my $.02

Edited December 30, 2003 by ucmike

December 30, 2003

“I can put a spare bulb in my hand

and light up my yard”

This works with a fluorescent bulb held up under high power lines. Try it when its very dark …. kinda spooky.

December 31, 2003

thanks for your input everyone. it seems we have many theories out here. it sounds like some lines may put off rf in different spectrums depending on conditions. maybe this is why some of you never have problems. the multi-wave theory is interesting. but there is a problem with it. i live in san francisco. i cache near tall metal objects often and my gpsr does not get as confused as it was under the powerlines. is this a problem unique to the e-trex?

January 2, 2004

I don't think it's confined to the E-trex. I just took a guy with me to a known trouble spot and his new Legend acted the same as my E-trex. Granted they are both Garmin products. I would like to see how something with a different antenna arrangement would fair.

1.1k · January 2, 2004

I have just recently started to really nail this down. I know my GPSr pretty well now. Once I am within 50 to 100 feet of a cache I usually stop and use a manual compass to make sure my bearings are right. I then plot the direction and distance to the cache and walk towards it slowly, following the map on my GPSr. 90% of the time it walks me to within a few feet of the cache. Sometimes it is not so obvious and I walk away and return, repeating the process.

That 10% I can do this numerous times and will often find myself standing in the same spot but the GPSr is showing variances up to 100 feet or more. The 3 caches I have done where this was an issue where all in open terrain but under power lines.

In each case there where other cachers who logged issues with the GPSr interference, but some logs say "coords right on". I realize I have solved nothing here.

Despite varying theories about why and how the powerlines interfere do we agree that they CAN interfere?

How about a little informal data gathering? If you have experienced what you think COULD be power line interfernce:

1. What make/model GPSr was it?

2. What time of day?

3. What was the temp?

4. Precipitation?

5. Distance from power lines?

6. Quantity of power lines?

7. Presence of any large physical structures? (cliffs, buildings, stands of tress etc.)

8. Distance from large physical structures? If applicable.

January 2, 2004

It sounds simmilar to when you use a cheap walkman radio near powlines, computer, blendor, or my favorite the microwave. To read about the shielding of GPS units refer to This Thread.

January 2, 2004

“I can put a spare bulb in my hand
and light up my yard”

This works with a fluorescent bulb held up under high power lines. Try it when its very dark …. kinda spooky.

same thing with a light bulb in a microwave,you put it in a cup of water up to the middle of the screw in part and turn the mic on and it will light up.

2.6k · January 3, 2004

Ok heres an odd one GC1427 the cache is called the buzzing might be rattlesnakes. (Its one of mine) placed on Aug. 3rd 2001 with about 70 visits, its directly under high voltage lines and is close to a tower, not a person has complained about the coords or their gps being off .

Although a few have coplained about bees.

I know 3 of the first 5 finders were using garmin etrexs, of course they were also the ones stung by bees. Just thought I'd toss this in to stir the pot

PS When I placed this cache I was still using my old Global Nav 212 byLowrance

January 3, 2004

“I can put a spare bulb in my hand
and light up my yard”

This works with a fluorescent bulb held up under high power lines. Try it when its very dark …. kinda spooky.

Yeah, I've done this before... my friend and I ended up being detained by twelve cop cars (slow night), while I was handcuffed and had my rights read to me. This was all before September 11. Mind you, we had a gun in the car, a hunting knife under the seat and my friend had lockpicks on him at the time, which didn't help.

Fourty-five minutes later the cops let us go, after they determined we really weren't breaking any laws. It was the story about trying to make the fluorescent bulb glow under the powerlines that got us into so much trouble in the first place.

Trouble With Power Lines?

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