Powerline Trail - "crackling" Noise Overhead

[+markp99]

I found an alternate route out from a cache along a poweline trail. I was about 1.2 mles from my car and the woods were very buggy (pesky deerflies!). The air was very clear out here with a refreshing breeze. This was also atop a decent sized hill, so the view at sunset was quite nice. A good choice if I do say so myself!

 

Anyway, as I walked along the trail, it passed directly beneath the powerlines. There was a clear high-voltage crackling sound coming from the wires overhead. This was a bit disconcerting as I feared the powerline might arc through me to the ground, which ruin my whole day.

 

I have walked along similar trails before, but do not recall this noise before.

 

Is this a normal effect?

Edited July 20, 2006 by markp99

[+TEAM 360]

I found an alternate route out from a cache along a poweline trail. I was about 1.2 mles from my car and the woods were very buggy (pesky deerflies!). The air was very clear out here with a refreshing breeze. This was also atop a decent sized hill, so the view at sunset was uite nice. A good choice if I do say so myself!

 

Anyway, as I walked along the trail, it passed directly beneath the powerlines. There was a clear high-voltage crackling sound coming from the wires overhead. This was a bit disconcerting as I feared the powerline might arc through me to the ground, which ruin my whole day.

 

I have walked along similar trails before, but do not recall this noise before.

 

Is this a normal effect?

 

Yes, the noise is normal.

 

Nothing to worry about, until you come down with a brain tumor in 30 years...

Edited July 20, 2006 by TEAM 360

[+LDove]

Be sure to put on your aluminum foil head gear prior to these excursions to protect you from both UFO brain altering rays and any stray electromagnetic fields.

[+Team Tecmage]

I prefer to walk along carrying a couple of fluorescent bulbs.

[+Confucius' Cat]

No real danger (depends on who you listen to).

 

Some claim that continuous exposure causes problems.

 

Just don't go climbing the towers and if you see a line down... the cache is NOT hidden there.

[+Criminal]

Keep your tongue off the grounding wire.

[bogleman]

Some big time voltage is making that noise. It will scare the crap out of you if you've never heard it before. Out one fine day I happened across a fine individual resting on one of the metal power poles, good view from up here he says, I bet.

[+StarBrand]

A hum is normal. A cracking could be normal or indicate a slight problem. Either way, you should be safe enough on the ground as long as the wires or towers don't fall on your head.

[+conradv]

I survey 230kV & 500kV BPA powerlines, & what you're hearing is pretty normal.

 

After you've been in a large Substation (a "meeting place" or switchyard if you will) and you can actually FEEL the voltage (we can't even raise our arms over our heads in a substation and have to be tested yearly), that's when it gets scary.

 

I don't like substations.

 

At all.

[+Airmapper]

You might get a charge out of such a hike if your this guy....

[+thedeadpirate]

and if you see a line down... the cache is NOT hidden there.

 

Sure it is, but rated a 10/10

[+fizzymagic]

Anyway, as I walked along the trail, it passed directly beneath the powerlines. There was a clear high-voltage crackling sound coming from the wires overhead. This was a bit disconcerting as I feared the powerline might arc through me to the ground, which ruin my whole day.

 

Is this a normal effect?

Yes. I was hoping that somebody would actually offer useful information to you, but you got a bunch of completely useless information.

 

It's called a corona discharge. It is NOT accompanied by a high electromagnetic fields on the ground; that's because the voltage is very high, so the currents are not. You receive a much greater EMF from low-voltage lines in your neighborhood.

 

Corona discharge from power lines is quite common. It generally occurs near points or sharp corners, because the electric fields are very high there. As a result, it tends to occur right at the transmission towers, because that's where the pointy stuff is. You can usually hear it better when the humidity is higher, because the conductivity of the air is higher. You can really hear it on foggy nights!

 

The electricity is not going to arc through you; it is discharging diffusely through the air, usually to the transmission tower itself, which is quite well grounded. The power companies try to keep it to a minimum, since it represents a loss of power.

[+Yellow ants]

I was hoping that somebody would actually offer useful information to you, but you got a bunch of completely useless information.

 

Hey, we're not all engineers, ya know?

 

 

I got the power (GCKH59)

[CoyoteRed]

http://video.google.com/videoplay?docid=4468957986746104671

[+horsegeeks]

http://video.google.com/videoplay?docid=4468957986746104671

 

That's amazing CR.

 

I remember it happening all of the time while growing up but not very often these days. I don't remember the last time I've heard it while geocaching or walking our pasture which partly is under powerlines.

[+CharlieP]

It is NOT accompanied by a high electromagnetic fields on the ground; that's because the voltage is very high, so the currents are not. You receive a much greater EMF from low-voltage lines in your neighborhood.

 

I agree with the rest of the post, but not this statement. Although the voltage in these transmission lines is high, so is the current. You can gauge current by the size of the conductor, and these conductors are large. So the EMF is large too. But brief exposure is nothing to worry about.

 

EMF Comparisons

[davwil]

The power line insulators can also make a crackling noise, although usually not too loud. It's a problem for the power distribution company because it means a loss of efficiency in the power distribution network. When the insulators get dirty or contaminated by salt ( like when the lines are near the ocean) the power company around here will wash them off with de-ionized water.

 

The arcing insulators can cause pretty severe radio interferrence. I've seen the power company find these insulators by listening for the arcing with a parabolic microphone .

 

If a power line is making an unfamiliar noise it could have been vandalized. Some people are stealing the copper grounding wire and thus removing the tower ground and causing a serious safety problem.

[+Vinny & Sue Team]

I found an alternate route out from a cache along a poweline trail. I was about 1.2 mles from my car and the woods were very buggy (pesky deerflies!). The air was very clear out here with a refreshing breeze. This was also atop a decent sized hill, so the view at sunset was quite nice. A good choice if I do say so myself!

 

Anyway, as I walked along the trail, it passed directly beneath the powerlines. There was a clear high-voltage crackling sound coming from the wires overhead. This was a bit disconcerting as I feared the powerline might arc through me to the ground, which ruin my whole day.

 

I have walked along similar trails before, but do not recall this noise before.

 

Is this a normal effect?

I useta be an electronics engineeer, and now wear a hat (that is, among other hats) as a scientist, so let me take a stab at this one: what you were hearing is called a corona discharge. It often happens on any conductor -- such as a powerline -- carrying high voltage in a gaseous atmosphere, and the corona discharge will primarly occur only off sharp points (i.e., wire kinks, wire ends, sharp bends, sharp edges, etc.) or in times of high humidity (because the air is a better conductor then) as some of the HV discharges into the atmosphere. BTW, as it discharges, it tends to ionize gases in the atmosphre, primarily nitrogen and oxygen, and this ionizaton will often form odoriferous oxidative compounds of nigrogen or oxygen, such as NO, O3 (ozone), which you may be able to smell at some distance.

 

Providing that you are on the ground and that the corona discharge is from powerlines far overhead, this discharge is not dangerous to you, although the relatively high near-field levels of EMF noise, particularly in the VLF, LF and HF spectrum, may cause some intereference to your GPS receiver if you are nearby, although most corona discharges do not produce much RFI (radio-frequency interference) at the UHF frequencies used for GPS signals from satellites.

 

Now, as for spending a LOT of time directly under powerlines, versus simply walking under one occasionally (which I do at times as well): there are some studies which seem to indicate that living near HV powerlines on a long-term basis can lead to all sorts of subtle and not-so-subtle adverse biophysical effects, including possibly elevated rates of some diseases, fatigue, and other disorders.

 

Interestingly, as an aside, there are companies which produce "protective" devices which seem to protect people and sensitive electronic equipment [such as high-end electronics equipment found in audio and video recording studios and in high-end audio and video playback equipment, in high-uptime computer centers, and in sensitive military communications systems] from much of the adverse effects of electromagnetic frequency (EMF) emanations from powerlines and other manmade electrical equipment; these devices are the size of perhaps a large DSL modem, and often have an effective treatment radius of over 100 feet inal directions. As a consulting scientist, I sometimes design devices using such technologies for some of the companies producing very high-end (read expensive) protective equipment for a number of markets.

[+fizzymagic]

It is NOT accompanied by a high electromagnetic fields on the ground; that's because the voltage is very high, so the currents are not. You receive a much greater EMF from low-voltage lines in your neighborhood.

 

I agree with the rest of the post, but not this statement. Although the voltage in these transmission lines is high, so is the current.

EMF Comparisons

You're right, of course. What I should have said is that the magnetic field depends only on the current, not the voltage. Which is why the graphs on the page you link make no sense to me, since they are labeled by voltage.

 

BTW, in response to other points raised about health effects of EMF: there has never been a reproducible replicated study showing any such effects from low-frequency powerlines.

[CoyoteRed]

Quite frankly, I'd be very worried. Everywhere you see these massive power lines you see stunted plant growth.

 

Just kidding.

[+RoyalRed]

Quite frankly, I'd be very worried. Everywhere you see these massive power lines you see stunted plant growth.

 

Just kidding.

 

Yeah...I think that's because it was cut down!

 

I grew up with high power line running right behind my house. Never had any health problems but I am now 156 years old!

[CoyoteRed]

Yeah...I think that's because it was cut down!

 

Yep, that EMF is wicked!

[+Vinny & Sue Team]

It is NOT accompanied by a high electromagnetic fields on the ground; that's because the voltage is very high, so the currents are not. You receive a much greater EMF from low-voltage lines in your neighborhood.

 

I agree with the rest of the post, but not this statement. Although the voltage in these transmission lines is high, so is the current. You can gauge current by the size of the conductor, and these conductors are large. So the EMF is large too. But brief exposure is nothing to worry about.

 

EMF Comparisons

Speaking as an EE and scientist, I must agree with Charlie.

[+What rock?]

Do you glow in the dark?

[+MountainMudbug]

There's a big powerline here that runs right thru a high-traffic shopping center, and it is always creepy to me to hear those lines crackling..... I just hot-footed it thru there again today after stopping at the craft store!

[+sparqui66]

Quite frankly, I'd be very worried. Everywhere you see these massive power lines you see stunted plant growth.

 

Just kidding.

 

There is a reason for the "stunted plant growth" you observed in and around power lines. I have two power towers on my property. GPU (First Energy Corp) sprays a natural defoliant in those areas every so many years. On alternate years, they try to just cut down the brush. Should vines/trees become wrapped around the towers or grow too tall, they could become a serious hazard. Yes, I hear them hum more when it's humid or raining.

 

I haven't started to glow yet!

[DrDark]

Team Tecmage said it but I will elaborate.

If you walk under a high tension line with a flourescent bulb in your hand (hold it by the end) IT WILL LIGHT UP all by itself.

Do this at night and WOW your friends. It's a great bar bet!

[+Vinny & Sue Team]

Team Tecmage said it but I will elaborate.

If you walk under a high tension line with a flourescent bulb in your hand (hold it by the end) IT WILL LIGHT UP all by itself.

Do this at night and WOW your friends. It's a great bar bet!

True.That is a great demonstration of the near-field EMF -- largely an electric field -- beneath the lines. On a vaguely-related note, I was a ham radio operator and electronics/radio buff as a kid. One of my friends lived in the Hackensack Meadowlands in northenrn NJ, and his home was located very near the AM transmitter tower for a large and very famous NYC-area AM radio station (it may have been 770-WABC). He had noticed early on that he could easily light a large fluorscent bulb by walking around in his backyard and holding it vertically (i.e., upright) due to the near-field EMF bathing his yard. He eventually strung a wire antenna around his yard (but within the limits of his property) and fed it to a device in his basement which he had designed to convert much of the stray near-field EMF energy bathing his backyard into usable DC electricity at 12 volts, and he used this 12 volt DC power to power some lights and small appliances in his house, and to charge a bank of storage batteries. He claimed that he was able -- during the daytime when the AM station was running at its maximum power level of about 50 KW -- to draw off several hundred watts of usable power from the near-field EMF.

[+Glenn]

It is NOT accompanied by a high electromagnetic fields on the ground; that's because the voltage is very high, so the currents are not. You receive a much greater EMF from low-voltage lines in your neighborhood.

 

I agree with the rest of the post, but not this statement. Although the voltage in these transmission lines is high, so is the current. You can gauge current by the size of the conductor, and these conductors are large. So the EMF is large too. But brief exposure is nothing to worry about.

 

EMF Comparisons

When gauging size don't for get about skin effect. Transmission lines, I have been told, are hollow because of skin effect.

[+The G-Team]

I live right next to one of the big power lines. Our daughter was born with a third arm. The Dr says its because we live near the power line. I don't think its that. I think its either the nuclear fuel dump ground next door or the toxic waste treatment center on the other side of the street.

[+Vinny & Sue Team]

It is NOT accompanied by a high electromagnetic fields on the ground; that's because the voltage is very high, so the currents are not. You receive a much greater EMF from low-voltage lines in your neighborhood.

 

I agree with the rest of the post, but not this statement. Although the voltage in these transmission lines is high, so is the current. You can gauge current by the size of the conductor, and these conductors are large. So the EMF is large too. But brief exposure is nothing to worry about.

 

EMF Comparisons

When gauging size don't for get about skin effect. Transmission lines, I have been told, are hollow because of skin effect.

Skin effect only becomes a significant factor at frequencies well above 50 KHz or 100 KHz, and only truly significant at RF frequencies above a few MHz. And, since AC power lines in the USA employ 60 Hz AC, there is insignificant skin effect at that frequency. So, there is no skin effect at 60 Hz, and I have never heard of any power lines with hollow conductors.

[+Glenn]

It is NOT accompanied by a high electromagnetic fields on the ground; that's because the voltage is very high, so the currents are not. You receive a much greater EMF from low-voltage lines in your neighborhood.

 

I agree with the rest of the post, but not this statement. Although the voltage in these transmission lines is high, so is the current. You can gauge current by the size of the conductor, and these conductors are large. So the EMF is large too. But brief exposure is nothing to worry about.

 

EMF Comparisons

When gauging size don't for get about skin effect. Transmission lines, I have been told, are hollow because of skin effect.

Skin effect only becomes a significant factor at frequencies well above 50 KHz or 100 KHz, and only truly significant at RF frequencies above a few MHz. And, since AC power lines in the USA employ 60 Hz AC, there is insignificant skin effect at that frequency. So, there is no skin effect at 60 Hz, and I have never heard of any power lines with hollow conductors.

Mythbusting in action.

 

Now I'm curious how do you gauge current by the size of the conductor.

[+CharlieP]

Now I'm curious how do you gauge current by the size of the conductor.

 

What I meant was that the current carrying capacity of a line is determined largely by the size of the conductor. Other factors, such as conductor composition (copper, aluminum, aluminum with steel core) also come into play. But if the conductor is big, then it is carrying a lot of current, or the power company is wasting their money.

 

Another interesting thing about conductors and corona discharges is that corona discharge is minimized by increasing the diameter of the conductor. To take advantage of this, ultra-high-voltage transmission lines often use three conductors (per phase) locked in a triangular configuration, and these 3 wires act like a single large diameter conductor, to minimize the corona discharge. In a sense, they act like a hollow conductor.

Edited July 24, 2006 by CharlieP

[CoyoteRed]

While the conductors are large, can you imagine the size they would have to be if the power company sent out 120v? The conductors near a power station would have to have thousands of times the current capacity. The towers wouldn't be able to support the weight. It would be like building a bridge everywhere you sent power.

 

Boy, those EE's are smart.

[+Crystal Sound]

Now I'm curious how do you gauge current by the size of the conductor.

 

What I meant was that the current carrying capacity of a line is determined largely by the size of the conductor. Other factors, such as conductor composition (copper, aluminum, aluminum with steel core) also come into play. But if the conductor is big, then it is carrying a lot of current, or the power company is wasting their money.

 

Another interesting thing about conductors and corona discharges is that corona discharge is minimized by increasing the diameter of the conductor. To take advantage of this, ultra-high-voltage transmission lines often use three conductors (per phase) locked in a triangular configuration, and these 3 wires act like a single large diameter conductor, to minimize the corona discharge. In a sense, they act like a hollow conductor.

 

The company I work for by day, American Electric Power, just recently energized a new 765,000 volt line. Normally our "765KV" lines are constructed in a bundle of 4 conductors per phase in a square pattern. This line was built using 6 conductors per phase, in a hex-pattern. The reason was the corona discharge noise was lower by something around 10 decibels by using this configuration.

 

I spend a fair amount of time in the large transmission stations. Yes, the noise is very normal, and isnt harmful. There are some mornings though, its particularly loud, and does make one cautious.

 

The most interesting experience was when walking through the station yard, underneath the 765,000 volt busswork. At certain spots, i could feel my bones resonate from all the energy. Didnt feel any electrical / static shocks, but it was certainly an interesting sensation.

[+conradv]

The company I work for by day, American Electric Power, just recently energized a new 765,000 volt line. Normally our "765KV" lines are constructed in a bundle of 4 conductors per phase in a square pattern. This line was built using 6 conductors per phase, in a hex-pattern. The reason was the corona discharge noise was lower by something around 10 decibels by using this configuration.

 

I spend a fair amount of time in the large transmission stations. Yes, the noise is very normal, and isnt harmful. There are some mornings though, its particularly loud, and does make one cautious.

 

The most interesting experience was when walking through the station yard, underneath the 765,000 volt busswork. At certain spots, i could feel my bones resonate from all the energy. Didnt feel any electrical / static shocks, but it was certainly an interesting sensation.

 

Probably my best story was when I was a teenager. I worked on my grandpa's potato farm (Northern Idaho) and we were laying sprinklers out in the field. They were 40' aluminum with center risers. I stopped the tractor in the field, and it happened to be underneath the 230kV line that ran through the middle of the field.

 

As I jumped down, I started to hear something. I looked around at my co-worker, then looked at the pipe wagon.

 

The pipes were vibrating. I looked up and noticed that the wagon was directly under the line. I believe that this line had 25' offsets.

 

Since I was the boss, I made my buddy jump up on to the tractor (I made sure to tell him to "jump") to move it.

 

We didn't park underneath the lines anymore, but you could feel a pipe humming moving it the 20 rows when we were under the lines. Come to think of it, I think I made him do those pipes too... It's Good To Be The King...

[+GClouse]

The reason for the high tension, high voltage lines is to distribute power over a large area. High tension refers the high tensile strenght of the power cables, which allows them to span a greater distance between support towers. High voltage AC can be carried a longer distance with less power dissipation from the resistance in the wire. at substations the voltage is stepped down to a lower voltage for local distribution, and the at the customer location it is stepped down again before it supplying the home or business.

 

The crackling noise is corona discharge. And it is mostly harmless. There has been some documented cases of nerve damage after long term exposure to high intensity electric fields, but with the exception of groups of people that work with high voltage equipment, this is extremely rare.

[+Vinny & Sue Team]

Now I'm curious how do you gauge current by the size of the conductor.

 

What I meant was that the current carrying capacity of a line is determined largely by the size of the conductor. Other factors, such as conductor composition (copper, aluminum, aluminum with steel core) also come into play. But if the conductor is big, then it is carrying a lot of current, or the power company is wasting their money.

 

Another interesting thing about conductors and corona discharges is that corona discharge is minimized by increasing the diameter of the conductor. To take advantage of this, ultra-high-voltage transmission lines often use three conductors (per phase) locked in a triangular configuration, and these 3 wires act like a single large diameter conductor, to minimize the corona discharge. In a sense, they act like a hollow conductor.

 

The company I work for by day, American Electric Power, just recently energized a new 765,000 volt line. Normally our "765KV" lines are constructed in a bundle of 4 conductors per phase in a square pattern. This line was built using 6 conductors per phase, in a hex-pattern. The reason was the corona discharge noise was lower by something around 10 decibels by using this configuration.

 

I spend a fair amount of time in the large transmission stations. Yes, the noise is very normal, and isnt harmful. There are some mornings though, its particularly loud, and does make one cautious.

 

The most interesting experience was when walking through the station yard, underneath the 765,000 volt busswork. At certain spots, i could feel my bones resonate from all the energy. Didnt feel any electrical / static shocks, but it was certainly an interesting sensation.

Great tale! Thanks!

[gulfscuba]

There are 3 caches in my area that I have been unable to find. Yesterday I went to one of them and noticed that it was close to high voltage power lines. My GPS jumps all over the place. I checked the other 2 caches and found that both of them are near power lines as well. After reading all this info I think I will skip caches placed near high voltage lines.

[+Renegade Knight]

In the past I've surveyed under 230KVA lines. At one point the line was about 30' (hard to estimate but it was close) above you. Over the course of the summer we noted that the corona effect varied by the atmospheric conditions. Some days it was worse than others. Most days it would make the hair on the back of your neck stand on end. You could always feel the 'hum' so to speak. When I say feel I don’t mean just hear it. Some days you could feel the power directly. Not a shock exactly but no doubt you didn't want to mess with the wires. We never did make it up there with fluorescent bulbs.

 

Anything that makes the hair on my neck stand on end is something I'd be careful about. As a bonus it mucks up your GPS signals. The bottom line on the effect is that it's a power loss. There is power, it is flowing, and the scientific jury is out on what harm that may or may not cause.

Edited November 14, 2006 by Renegade Knight