The Birds on High Voltage Power Lines Question

With no circuit there is no electron flow.....The bird is just like a bag of water hanging from the line...The bird carries no charge...

I'd add - the net total of electrons and protons in the wire is constant. It's an EM wave traveling through the wire, like a wave on the ocean. As the wave moves (towards shore, or down the wire) the individual molecules of water (or electrons) only move a little bit.

And - there are as many protons as electrons in the bird. Any EM field the electrons 'see' is also 'seen' by the protons so the net effect is zero.

"I'd add - the net total of electrons and protons in the wire is constant. It's an EM wave traveling through the wire, like a wave on the ocean. As the wave moves (towards shore, or down the wire) the individual molecules of water (or electrons) only move a little bit."

Right. So the electrons are displaced a bit, till they displace other electrons which displace other electrons. Would that be right? And in this the electrons on the bird's feet aren't disturbed. Would that be right?

"So the electrons are displaced a bit, till they displace other electrons which displace other electrons. Would that be right?"

Yes, the electrons are displaced a bit. A tiny, tiny bit.

Say you have a 10 mm diameter copper wire carrying 300 amps. Were this a DC current, those electrons would move with a net drift velocity of about one meter per hour. As it is an AC circuit and assuming it is 60 Hz, those electrons will move at most (on average) about 2.1 microns over a half cycle and, over the next half-cycle, move back, resulting in an overall long-term net drift velocity of zero.

"And in this the electrons on the bird's feet aren't disturbed. Would that be right?"

No, they are disturbed. Don't forget: there's an electric field around that wire and charged particles (electrons, ions and polarised molecules in the case of the bird) respond to electric fields. There is also an AC current flowing through the wire, producing an AC magnetic field. As birds are somewhat electrically conductive, the changing magnetic field induces small eddy currents in the bird - just as it does in any other conductor. Birds are not immune to the laws of physics.

the changing magnetic field induces small eddy currents in the bird - just as it does in any other conductor. Birds are not immune to the laws of physics.

And I imagine the magnitude of these eddy currents is small. Of what order is it, and how would one calculate that?

I'm guessing microamps, perhaps? Depends on the current in the wire and it's relationship to other current-carrying wires nearby, the size of the bird, shape of the magnetic field.

How to calculate, precisely? With great difficulty.

How to get more-or-less in the ballpark? Model the bird as a bag of electrolye in which both electrons and ions play a part, or simply as a chunk of material having an equivalent resistivity. As a piece of graphite of comparable size, maybe?

There is a circuit. The one from from the station to the ground. I understand the bird is just touching one potential, and not ground.

But since there is a circuit (the actual power transmission circuit), the electrons are flowing through that wire right?

Power lines are most metal wires that are transporting AC current. They are at a AC voltage referred to whatever level potential you desire.

When the bird sits on a wire, it has the same potential as the wire it sits on, considered that the legs are not an absolute isolator.

If you have your bird with electrons, they feel happy to stay where they are.

In the bird.

I think it will get a little bit warm around the feet!

But thats not electrons it is the magnitronic waves emitted by the power lines!

Go figure!

No...

Never seen these power lines cooling down that much that the icicles hanging off it in the obvious bright summer day!

What effect is that if not Antimagentronic?

In case you are not being funny.

What exactly is a "magnitronic wave"?

Must have been funny then!

There is an AC electric field surrounding the wire. A charged particle will move in an electric field if it is free do to so. In metals, conduction-band electrons do the moving; in ionic solutions and electrolytes, both electrons and positively-charged ions move, but in opposite directions. As electrons are much more mobile, they do most of the moving.

Birds can thought of as bags of electrolytes. As they perch on the wire their free electrons respond to the electric field by moving in sync with changes in the field's strength and polarity. When the field's polarity reverses, so does the direction of the electrons' motion. This is true even if the bird is not in direct contact with the wire, but only within the electric field's influence; the bird's electrons (and mobile ions) need only 'feel' the electric field in order to respond.

So why don't birds perch on very high voltage wires? 750 kV, cross-country transmission lines, for instance? Corona discharge, probably. Methinks the intense electric fields around those wires would tend to make things a bit uncomfortable for our feathered friends.

Don't know about 750KV but they certainly rest on 500KV lines. Have three power lines nearby two 250KV and a 500KV. No difference in which they prefer, either one instead of the trees nearby.

Good Luck, Old Salt

When we see birds perching on the wires, they never perch on the phase conductors but only on the grounded shield wires above. I wondered about their obvious preference and reckon that it's probably a combo of the phase wires being too big around to afford a good grip (they're something like 1.5" dia) and that the strength of the electric field is highest near pointy objects. Birds' beaks are pointy and the electric field may be high enough to produce a corona discharge. If you've ever had them you know that corona burns hurt.

When I see birds they are on all wires, not just the upper ground wire. Also I rarely see corona on the wires. See many birds though.

When the Power company takes us for tours of the local power station (transformers, one of the largest in the state) they tell us to walk directly, with short steps and in the direction towards or away from the equipment. They say not to walk with your feet one closer to the equipment than the other. The personnel say that there are "electrical gradients" within the soil and will create shocks and could possibly kill us.

The birds don't show any damage from roosting on the "hot" wires and it certainly is far away from the foxes.

Good Luck, Old Salt

Well, all I can say is that our birds show a definite preference for one over the other. We never see birds perching on the phase conductors. Not ever. Possibly it is because the field at that voltage (750 kV) is strong enough to cause discomfort. Possibly it is something else. Hard to say.

Interesting about your tour. If you go on one again, take a DVM with a high-voltage probe with you and poke the probes into the ground a few feet apart. I'm also curious why they're conducting tours in an area where "one wrong step could kill you." I hope their insurance is paid up.

I was wondering a long time if the bird weight is part of the desgin criteria for power lines. Lets say a flock of birds in addition to wind/ice and other loads!

_{As per above power lines freeze over on summer days but then there is no bird sitting on it right?}

_{What a silly day!}

This was a fire dept familiarization tour of the facility. On the second or third tour I attempted to take some voltage reading but was told by the power company personnel not to do it since it was too dangerous. He then stated that if I persisted and disobeyed their orders I would be "politely" told to leave, with an escort of course. At that point I stopped because I "didn't want to set a poor example for the younger members"

What is ironic is that during January there was an explosion of one of the 250KV transformers while it was being brought into service after PM. There was 10,000 gallons of mineral oil involved and all they said was to keep our water streams off the live wires, some of which were 500KV and less than 10 ft above our water stream. No reminder about the walking or anything else. Took 5 hours of set-up and extinguishment with a rate of 2,000gal/minute of water and foam to put it out. Ironic isn't it that what was important then was not so important if they were loosing money!

Good Luck, Old Salt

It wouldn't have been at this substation in Florida, would it?

No, but they were about the same in size and veracity. For all purposes they were about the same. One of the biggest fires I have been involved with.

Good Luck, Old Salt

Is is known as Step and Touch potential and if they were teaching you properly they would tell you never to take a step, but to shuffle your feet ro keep your feet close together and hop. One gets varying voltages across each gardient therefore a simple step can put one across two differning potentials and then it can be Goodbye world. And, it would only happen under a fault condition. Normally subs are safe to walk in.

We have the procedure and it has been verified by the power company that under no situation or conditions are we to enter the substation without one of their technical person. We are there to assist them and they will tell us what they want us to do. If at all possible we require that the escort person stay with us at all times if possible. Another procedure is that we wait at the curb and don't force an entry until the company representative shows up. This is under no situation will we enter. Personal safety comes first!

Even with my electrical knowledge and experience I will not do anything there without a consensus of all entities involved. This is what the ICS, Incident Command System, is all about.

I guess they tell us about the ground gradients so that we will be prepared in case it is necessary. Better to know and not need it than not know and need it. With the incident I mentioned the plume of smoke was seen 8 miles away and the "thunder" over a mile away.

Thank you for the information. It is those bits of knowledge that each other can provide for the use of others and to keep them safe and healthy. A GA to you sir!

Good Luck, Old Salt

No, the thunder was not "seem or saw or visually observed". With light, a transmittal of extremely short wave length, the visual senses are stimulated. With thunder, since it is a compression of air, the frequency of the air compressions determines the pitch and the intensity of them determines the strength, usually expressed as db's (decibels). It also can not be seen. With turkeys when they see lightning they look up towards the sky. When they hear thunder they also look to the sky because lightning and thunder usually occur simultaneously. While doing this the rain that follows the lightning and thunder indirectly causes the turkeys to kill themselves. They look up at the lightning and the rain with their mouths open in dismay. They are too stupid to close their mouths while discussing whether the sound is heard or seen so they drown in the rain. Therefore is everyone who even considers questioning if thunder is seen a TURKEY? Certainly appears so.

Lightning causes a flash. Thunder causes a clap. If someone can't see with the flash does that mean they are going to get the clap? Engineers can see with light. They can also hear thunder. Due to the differences in speed of light, 186,000 miles/sec, and sound (at sea level), 761.207051 m/hr or 12.020118 m/min or 0.200335 m/sec, the light can be used as a warning about the thunder to come. (Remember the count by ones for 5 seconds for each mile to determine how far the lightning was away from you from Scouts?) If you don't use the lighting to check things out first does that mean you will get the clap?

If it is not stated whether thunder is seen or heard, anyone who would even think that thunder had been seen is probably a TURKEY with the CLAP. This also applies to those who ridiculously support the questioning of whether thunder was seen!

Good Luck, Old Salt

Gene Hayes-

My intentions of the posting were not to be venomous or derogatory. Although it apparently was not obvious it was to make fun of ourselves as engineers. How many times do we concentrate on one thing and are oblivious to the things going on around us. Not all engineers but at one time or another everyone does this even if slightly and quickly. Also some times we are so called experts but we forget the small things such as the polysemous word "CLAP" (look that up in your Funk & Wagnalls, if you are old enough to remember "Laugh In"). You were the unfortunate person to recognize a common clarifying omission of a word. I thank you for this and hopefully not being overly aggressive in your comments about my posts. The last part was intentionally put there, not directed to you, but to those few who frequently posts in a vary malicious manner if you do not genuflect to their postings.

I do not like to post malicious replies nor do I like to receive them. What does send a bug up my rectum is those who make remarks questioning one's mothers lineage, who one's father was, vicious, derogatory and whose only reason for posting is to appear superior to others. I have only done that when posters strongly and repeatedly do these things to me or others that don't deserve anything like that.

Again, I apologize for misunderstandings and especially to you. Thank you for your time. I already gave you a GA!

Good Luck, Old Salt

What's a verb??

Good Luck, Old Salt

GA

Its nice to read a post from someone who really knows and understands what he is talking about and can "put it over" in a manner that anyone can understand. Far too seldom here sadly....

Many thanks.

By the way, you beat me to it!!!

Thanks for your kind words.

That is called "step voltage". It is developed across the resistance of the soil or whatever the surface, or if swimming, the water. As your stride increases the reistance also increases with a resulting increase in voltage. The field radiates outward from the source. As bird's feet are relatively close together and the resistance of the wire, is negligible, birds are immune. If one were really interested one could calculate the ESR of a bird at 50 and 60 Hz and determine the capacitive heating of the bird. If you carry this out to the extreme, PETA may insist that umbrellas be strategically placed on the powe lines.

Next time you see a bird in electrical engineering you will know!

In my electrical engineering classes there were no wire roosting birds but there were a lot of TURKEYS.

Good Luck, Old Salt

I think birds usually like the highest roosting spot.

I wondered about their obvious preference and reckon that it's probably a combo of the phase wires being too big around to afford a good grip
NAAA! its a tiny built in VOM.

And, of course, a big however, if the bird manages to bridge the gap between the wires, it's free fried chicken! This happened a lot to eagles, that's why they put those higher, wooden T-shaped perches on power poles.

I think that would only take place if there was a very high gradient of electrical potential present, the Wien effect.....

You're forgetting your Basic Physics. Electrostatic induction, Mr. Eagle! And you didn't thoroughly read your wiki page! For shame, Mr. Eagle! For shame!

The Wien Effect describes increased mobility and conductivity in the presence of electric field gradients, not merely mobility, mobility which occurs even in the absence of an electric field due to thermal and quantum effects. Apply an electric field and those electrons will fall in line and move accordingly, like soldiers having received their marching orders. The Wien effect is something else entirely.

An electrostatic charge resides on the surface only...so the unknowing bird in question may be less likely to drop a feather, or perhaps attract a bit more cosmic dust, but his internals remain uncharged....of course quantumly speaking the bird may vanish at any time...

How did those charges get there, on the surface? They moved there. How? Through the conductive medium, under the influence of an electric field. Their being on the surface is the equilibrium condition if this were an electrostatics problem but, to arrive there at the surface and come into equilibrium, they had to travel there from somewhere else - an electric current. Now, because this is an AC field, they never reach equilibrium. They're always on-the-move. It's why the bluejays wot perched on our service drop in Texas always sh!t all over my truck.

I'm pretty sure that squirrel is responsible.....

I don't think it is a valid response to the OPs question but I just have to give that picture a GA.

There clearly is capacitance between the wires without the bird being present. The bird is going to change that capacitance, and there must be displacement charge that occurs (through the feet of the bird). If this charge transfer at 50/60Hz is small enough, the bird will have no perception of this. There also is coronal discharge, from the electric field between the bird and adjacent wires. I have no observations of high voltage lines as you indicate birds do not perch on. If this is true, then coronal discharge must be perceivable by the bird on the wire.

Does it get warm around the feet then?

Probably a little, which is why they like it in the winter.

Birds are tough.

Tell the Missus to take them out of the oven sooner.

Right!!!!!!!!!!!!!!!!

I might as well tell her that her dress makes her look chubby.

Well, you could tell her the dress makes her look 'undertall'.

Might as well tell her the meal sucks.

She'll just quit feeding me then.

Do I take it you speak from experience?

Yes, my first wife.

The Price of Diplomacy.

Maybe the're sniffing the ozone....?

http://www.endesa.com/EN/SALADEPRENSA/CENTRODOCUMENTAL/Publicaciones/Birdsandpowerlines.pdf

Here a though. When power Co's work on the high tension lines by helicopter. The person that goes onto the line is dressed in a metal mesh suit and they tether the helicopter and them self to the wire. With the tether there is a arc as everything comes up to potential of the wire. Here a YouTube video.

I know the helicopter is much larger than a bird. The corona around the very high voltage lines could affect the birds. But the lesser voltages and size of the birds may not affect them as much. Like someone said about walking through a voltage gradient field.

In the past I've heard of large flock of birds roosting on lines, then one flies into an open space completing the open circuit that shocks the whole bunch_.

Charles

I was told, I haven't attempted to verify it, by an electric company lineman that the arc is mostly static electricity created by the helicopter's rotor repeatedly moving through the air. He claimed the rotor is a high static generator. As said, I haven't tried to verify this.

I do know that this guy used to be one of the HV power line service people and is now a low voltage service person due to injuries incurred on a HV line. Could the helicopter story and the injuries be due to the same lack of intelligence?

Good Luck, Old Salt

http://realitypod.com/2011/03/helicopter-static-electricity-phenomenon-explained-corona-effect/

Years ago I flew out of Lincoln, Nebraska very early in the morning and just as the sky was barely starting to get light. I had a window seat in the back that happened to look out across one of the engine intakes. As the engine revved up a doughnut-shaped ring of faint blue light suddenly appeared immediately in front of the intake, about the same diameter, and then was sucked into the engine.

What was that all about? Anyone seen this effect?

Yes, it usually happens just before the engine explodes, killing everyone on board.

You lucky day, I guess..................................................................................

_{I don't have a clue.}

Looks like a momentary low pressure vapor event....

https://www.youtube.com/watch?v=Ii0nUcm24Jw

Leave it up to the Chinook, they can do about anything! Thanks for the photos! Now I know about it.

There have been two very interesting helicopter flights I have seen, one I was in. First was seeing the inspection of the local 500kv and 250kv lines several times. The copter flew about 10ft above the towers to inspect the tops of the wires and about the length of one end of the rotor and 10ft away to inspect the sides on each side. Second was in a small Plexiglas bubble type by Bell. It was a 2 passenger but we squeezed three in it with me in the middle. Our task was to take low altitude photos of some plants in NYC. After that was done we flew down to the shore of NJ to land. On the way we flew UNDER the Verrazano Bridge across NYC harbor. When we landed I had to change my underwear. One of the best moments of my life!

Good Luck, Old Salt

I agree about the helicopter's rotor static effect.

Here a few videos using boom trucks. Workers playing with power lines. Bare handing transmission lines.

Charles

Yes helicopters generate a static charge in flight. That's why Army ground crews use a grounding rod to discharge hovering CH-47s before attempting to hook them up to cargo loads on the ground. Failure to do so can result in being knocked on your a_s.

Scary video. Don't like high voltage or high places!

I like the adrenaline rush.

Due to step potential the bird's body definitely is affected by the the voltage and by the amount of current flowing through the wires.

The affect is supposedly minimal and not readily apparent however to my knowledge there has not been any studies on birds to scientifically determine the long term affects of the contact.

There is recorded evidence that electrical maintenance workers working in close proximity for extended periods of time and/or in direct contact with high voltage transmission lines and equipment have a higher incident of bone marrow disorders and other maladies than those that do not work on HV.

When working in 250KV and higher voltage switchyards/substations there is enough induced voltage in the human body to produce severe static discharge at distances of 50+ feet.

"When the bird flaps its wings and hits both power lines at the same time a large, puffy fluff ball of feathers will replace the space formerly occupied by formerly a bird. This demonstrates considerable current flow."

And this also explains the power companies' preference for putting the 'ground wire' above the phase wires on the power lines. Larger birds will tend to seek out the highest perch, and definitely won't pick a lower perch if the higher one is going to be poking them in the back of the head. Putting the 'safe' wire on top reduces the incidents of 'Fresh roasted eagle/hawk al ComEd.'

There are HV (400 to 750KV) DC lines also. So I too will be interested to know- whether the bird will experience any shock if at all if shifts from a positive or a negative line and then- even sits on a solid conducting ground surface or moves to opposite potential line. I understand that when air-crafts move through a charged rainy clouds- they collect charges and as it lands - it is electrically grounded immediately.

I do not know about the rest of the world but in UK almost all power lines of 275kV and above have on each phase four conductors in a 10"x10" configuration and held apart by spacers every 50-60m. The 275V creates a plasma field and most of the current passes through the plasma rather than the metal conductor wire. High voltage cannot be prevented from creating a plasma so it makes sense to take advantage of the phenomena and use it as a cheap way of transferring power? I don't normally see birds perching on phase wires but often see them on the top earth wire.

Multiple conductors on each phase are there to increase the overall current-handling capacity, not to create a 'plasma field.'

Don't know about birds on a wire, but can tell you first hand what happens when a squirrel manages to get inside a main plant panel. There are lot of ways to contact ground there.

As far as I saw only the electric field was mentioned. But an electromagnetic field can also appear. Birds have "magnetic sensors" to guide themselves. It could be possible that flowing currents develop electromagnetic fields too intense for them and that could be the reason they avoid to stay on.

Did anyone sees he video, / time lapse photography of an attempt to keep sea gulls from landing and s**** all over a remote weather sensing, or station? They put a 12V field into the railings that the birds were lighting on, with the hope that the current would deter the birds from landing. The video shows that the birds learned, very quickly, to lift one leg up, then put the other leg down, in a sequence that did not allow the current to complete it's circuit--It is hilarious-They look like the Rockettes, on a stage… Wish I could find it...

Please do.

Were these rails segmented with adjacent segments having opposite polarities?

No-- They were single rail tops, and cable rails. To see these birds lifting their feet up and down was hilarious.At times they were in sync...