FIELD a fluorescent array, wirelessly powered

richard-boxs-light-field

What would you do if you were driving along the highway and you glanced into a field to see a giant array of fluorescent tubes lit wirelessly from the electromagnetic fields of power lines. Back in 2004, [Richard Box] set up this display after hearing about a friend playing “light saber” with fluorescent tubes under power lines. The tubes can be lit pretty easily by have a variation in voltage between the ends. By sticking one end in the ground and the other up in the air, he’s harnessing the strong magnetic field from the power lines. Though some thought the display was made to bring people’s attention to possible hazards of living near the lines, [Box] states that he did it just because it looked cool.

[via io9]

Comments

  1. pedantic says:

    “Variation in voltage between the ends” is caused by electric field, not magnetic field.

  2. Joshua says:

    Cool indeed! Tesla used to do similar things, of course, outside his Colorado Springs laboratory.

    I can’t help but feel sorry for any backyard astronomers near this display, though. ;)

    pedantic: Technically, you’re both half-right and half-wrong. The power lines generate a magnetic field. However, this magnetic field induces an voltage difference across the lights that has an associated electric field.

    Electric and magnetic fields transform so readily that it almost doesn’t make sense to treat them as different things.

  3. cas says:

    ‘“Variation in voltage between the ends” is caused by electric field, not magnetic field.’
    by pedantic

    if my physics is correct the power lines have an electric field flowing along their length but emit a magnetic field perpendicular to the line that can induce a electric field in another conductive object

  4. andrew says:

    they do emit a magnetic field, yes. but to my knowledge that’s not what is causing the bulbs to light up.

    there is an electric field in the air which decreases in potential the farther away you are from the power lines. this is what is causing the bulbs to light up. the article agrees:

    “…powered entirely by electrical fields generated by the power lines that float in curves over the top of this field.”

  5. sam says:

    Okay, all of you. It’s not the decreasing potential from the line. The line has AC current. That current is both electrical and magnetic in nature.
    The changing current sets up a fluxing magnetic field around the line. Loops inside the field experience a current. That lights the bulbs.
    In return the current in the bulbs emits a magnetic field that affects the power line. This restricts the change of current in the line, shifting the power factor. The power company has to deal with this. It’s something like theft, afaik.

  6. anon says:

    this works by electromagnetic Inductive Reactance. The gases in the tube are excited by the fields of flux, thus producing light.

    http://en.wikipedia.org/wiki/Lenz%27s_law

    http://www.magnet.fsu.edu/education/tutorials/java/inductivereactance/index.html

    http://www.magnet.fsu.edu/education/tutorials/java/magwire/index.html

  7. Einomies says:

    AC isn’t “both electrical and magnetic”. All current creates a magnetic field. Nor is it creating a “fluxing” field – the field itself is called the magnetic flux.

    Magnetic effect has nothing to do here, because there isn’t a complete inductive loop through the tubes. To steal power from the wires through induction, you would need to have a wire running parallel to the power lines.

    What you see here is only the potential difference between the ground and the wirings that carry several hundred thousand volts. That easily amounts to hundreds of volts per meter of potential difference. There’s a constant leakage current in power lines due to the fact that the air conducts a tiny amount of current. It’s basically a large leaking capacitor.

    These tubes contain low pressure gas which provides a lower resistance path than the surrounding air, which concentrates the leakage current through them instead of the surrounding air and it actually increases the leakage slightly.

    it wouldn’t matter one bit if the wires were carrying AC or DC.

  8. Clay says:

    Go find yourself an AM radio station transmitter site. You can walk around carrying a lit tube. A friend of mine was an engineer and they had some tubes hanging from the ceiling in just loops of string inside the transmitter building, And it was well lit. I always thought that was the craziest thing and didn’t even believe him till I saw it with my own two eyes. The phenomenon by the way is caused by an Electro-Magnetic field, So you are all right (And wrong sort of)

  9. Fox3 says:

    I just had a thought. I’ve heard of a lot of weird ways to be ‘green’ but I’ve never seen anyone take advantage of this effect. Do you think it might be possible to power a house with this?

  10. James Clerk Maxwell says:

    Stop bickering and read about my work at Wikipedia: Maxwell’s equations.

    Also read the work of the distinguished scientists Michael Faraday, Heinrich Lenz (Lenz’s Law), and Nikola Tesla.

    All of this bickering over electromagnetic inductance is making me spin in my grave.

  11. dax says:

    it’s technically theft, since they’re removing energy from the electrical grid without being metered/paying. It’s not “green” in that you’re recycling or using “waste” energy.
    The load of this field wouldn’t be very significant w.r.t. the high tension lines, though.

  12. Man On Fire says:

    fox3; yes, but not without pissing off the power company who owns the transmission lines. you’re essentially stealing power from them.

  13. Fox3 says:

    wait, isn’t that energy being wasted anyway or would it actually affect their lines? I somehow got the idea that these rows of light were just making the existing field visible, not pulling power from powerlines.

  14. Ninja says:

    Very cool.

  15. aficionado says:

    Though some thought the display was made to bring people’s attention to possible hazards of living near the lines

    i wish that i could post a facepalm picture in respect to this statement

    if you run the calculations, the magnetic field generated by the lines is less than the magnetic field of the earth

  16. chris says:

    Yes, they are wasting the power companies power. You could also put a giant coil of copper wire under the power lines and run appliances with the inducted power.

  17. andar_b says:

    MoF – “you’re essentially stealing power from them.”

    You really ought to read the previous comments before posting. The lines leak current, through the air, to ground, as Einomies said. The lamps are only accelerating this process, not creating it, it is not induction.

  18. andar_b says:

    “if you run the calculations, the magnetic field generated by the lines is less than the magnetic field of the earth”

    That may be true, but living in constant contact with that much EM is unlikely to be healthy. I don’t sleep in a faraday cage or anything, but many kinds of EM are dangerous to humans in one way or another.

  19. Zeiris says:

    “That may be true, but living in constant contact with that much EM is unlikely to be healthy.”

    Better start living in one then, because the Earth’s magnetic field is gonna FUCK YOU UP!

  20. aficionado says:

    “That may be true, but living in constant contact with that much EM is unlikely to be healthy. I don’t sleep in a faraday cage or anything, but many kinds of EM are dangerous to humans in one way or another.”

    there is no may be about it

    magnetic field strength drops off with the square of the distance

    at the height that the highest voltages lines are, you cant differentiate the magnetic field of the lines from the earth

    take a compass under one and see what happens, it will still point to magnetic north with no perceptible interference

  21. Tim says:

    “take a compass under one and see what happens, it will still point to magnetic north with no perceptible interference”

    Well it probably wouldn’t move even if you put it right next to the wire since it is an AC field.

  22. sanchoooo says:

    What you have in essence is a big air gap transformer. Yes it is stealing.

  23. cynic says:

    The fact that this energy “would be wasted anyway” is neither here nor there and will not stop energy companies filing cease and desist against anyone who does it.

    The water pipes leak, sticking a tap on one and watering your garden is still stealing.

  24. Tom says:

    No, it’s /not/ a transformer.

    The effect really is caused by the electric, not the magnetic field.

    However, placing sharp objects like the tips of the flourescent lights under the powerline can indeed cause the power loss of the line to increase. The reason is the increased ion density in the air. This increases the corona losses (spray discharge losses).

    See http://en.wikipedia.org/wiki/Corona_discharge

  25. ab says:

    The earth´s magnetic field has a huge difference to this AC-electromagnetic field: it is not alternating 60 times per second, but rather turning slow (once every thousand years or so). Given that there are a lot of people living near powerlines of this strength, science knows almost nothing about the long term effects of this environment. Just statistical data with an outcome that a lot of people would not like to see.

    However, by changing the dielectric between line and ground you are increasing “the leak” of energy, therefore “stealing”. Ideally you would be using a copper wire or coil as near as possible to the power line to have maximum effect.

    Tubes like these need around 90 Volts outside of an field to keep emitting light. But here they omit a starter circuit (supplying the initial lightning bolt and heating the anode/cathode), as the electrons in the tube are accelerated by the field alone and affect the inner coating to emit light.

    There have been suits addressed to people lighting their garden with wireless power from an FM transmitter, too.

  26. Tom says:

    One additional comment:

    It’s likely neither the magnetic nor the electric field /itself/ that causes the bulbs to glow.

    It’s much rather the ion flux in the air that is contributing to the business amount of the electric current that flows through the lamps.

  27. albert says:

    “I just had a thought. I’ve heard of a lot of weird ways to be ‘green’ but I’ve never seen anyone take advantage of this effect. Do you think it might be possible to power a house with this?”

    No it wouldn’t…it’s not green in the first place, but just because it’d be interesting to figure out, let’s do a theoretical. A typical home has a minimum 100 amp service entry, with 200 amp services not uncommon. Assuming the field directly below a high voltage line is on the order of 10 microteslas according to a Google search result I found, some quick and dirty Lenz Law tells me that if you had a 1 meter square “antenna” you’d have to have nearly 60,000 turns of wire (about 14 miles) to get 220 volts, and if you’re going for 100 amps that means wire gauge in the single digits (according to awg, you’d use 2 gauge wire for transmission). that’s about a cubic meter of copper, or nearly 9000 kilograms. i certainly wouldn’t want to foot the bill for that much copper.

  28. poiromaniac says:

    knew about it but didn’t realise this was poss.
    There will be a certain field in Glastonbury with these around my tent this year

  29. albert says:

    @whomever thinks the fields are wasted energy:

    they’re not wasted energy because they’re inductive losses. inductors create a magnetic field when they have current passing through them. when the power is cut off, the field collapses and the power is returned to the circuit. the magnetic field is just a holding place for the energy the inductor has stored.

    the fields are there because current is flowing through the power lines…that’s just a fact of nature. it’s kind of like paying a security deposit on an apartment…the money is yours but not in your hands, and as long as you want to stay in that apt that money will not be available to you. if you move out, you get that money back and can spend it as you please. same for the power company…the field is there because of physics…it’s a loss in the system that they just have to accept since fields are thrown when you’re passing current through a conductor. it’s still their power, and if they ever turn off the line it’ll be returned to them and they can do with it what they please (sell). that’s why power lines have capacitor banks…to deal with our inductive loads being turned off and power being returned to the utility company (which they charge you for, actually).

    taking energy from those fields is no different than taking leaking water from a main, as cynic so eloquently put it. ab also mentioned power being siphoned from fm transmitters; my physics professor told us about someone doing that, and got caught when the transmitter technicians noticed their fields were really out of whack. i’ve also heard from my electromagnetics professor that people have been caught burying wires under power lines and picking up on the field that way. the point i’m making is that when you do that, the power company (or transmitter company for fm) notice additional losses. you’re not taking free, wasted energy because you can’t just grab energy from nothing, that’s physically impossible. when you interact with those fields you’re taking energy from the system, which is noticeable, which is my entire point.

  30. aficionado says:

    “Well it probably wouldn’t move even if you put it right next to the wire since it is an AC field.”

    there is a push towards dc transmission lines because they are more efficient

    even then, there will be no perceptible variation in the compass

  31. albert says:

    “there is a push towards dc transmission lines because they are more efficient”

    uh…what? are you sure your name isn’t thomas edison?

  32. aficionado says:

    for long distance interconnects for ac lines they are because you dont struggle to keep the frequency up

    google it

  33. albert says:

    @aficionado

    i see what you’re talking about with long distance, using hi voltage dc…interesting stuff.

    as far as why, though…when you say frequency, do you mean phase? i’m not a power engineer, but i can’t think of how frequency would be changed over long distances but i certainly can think of how phase would be difficult to deal with.

  34. aficionado says:

    my mistake

  35. photoshop.

    That’s a bit of exaggeration there in the photograph.

  36. RoboGuy says:

    I can’t believe no one else has said what I’m about to.
    Here goes:

    NOT A HACK

    just kidding, though – they don’t ALL have to be hacks.

  37. ohmygod says:

    omg, google it or shut up. i think its the kool-aid man’s tears that light the bulbs.
    no no
    give me a second, i can make more wild speculations!

  38. Solenoidclock says:

    In this thread, physics fights, old news, and fuzzy math.

    …can one of you guys tell me how much copper it would take to run a go-kart off of a tuned coil below these lines? If it’s less than 300 lbs, worth it.

  39. nick says:

    I went to college and i covered this in one of my electrical theory classes, an yes it is stealing.

    @aficionado
    dc power transmission is impractical, it has far higher power loss over same distances and you cannot efficiently step up and down voltages.

    And on a more serious note, when i stand under one of these it makes the metal plate in my head hurt, i am not shure if im conducting or resonating…. i just try not to stand under the transmission lines for emf leakage concerns anyways besides the pain.

  40. albert says:

    @solenoid clock:

    yes, actually i could tell you. just tell me how many horsepower you want and how much the driver weighs, and i’ll do the rest. and that would be freaking awesome if you could do it.

    @nick re: dc transmission lines

    i thought so too, but i was proven wrong. check out hvdc (high voltage direct current) transmission:

    http://en.wikipedia.org/wiki/HVDC

    there are practical applications to it and it’s used extensively in certain situations. besides europe there is an install right here in the states, feeding the debauchery of los angeles called the pacific dc intertie:

    http://en.wikipedia.org/wiki/Pacific_DC_Intertie

  41. razorchris says:

    very cool

  42. ac7zl says:

    You are comparing apples to oranges. The Earth’s field is essentially static. The field from the power lines is sinusoidal and oscillatory.

    The effects of long term exposure to transmission line fields are unclear, but concerns go back decades and there is some evidence to support those concerns. I, for one, would not want to live near them.

    As a side note, you might find “The Body Electric” by Dr Robert Becker interesting.

    ac7zl

    >if you run the calculations, the magnetic field
    >generated by the lines is less than the magnetic
    >field of the earth
    >
    >Posted at 3:38 pm on Apr 10th, 2009 by aficionado

  43. niun says:

    Ah, I would love to see a photo of this taken from above. Maybe you could see field lines in the intensity of the lamps.

  44. carsloth says:

    the lites were powered buy magic. Don’t you know any thing about science? All i know is I’m not comfortable standing under those lines. God did not evolve me to conduct ac current or dc with out bad things happening. I’m not a doctor or a scientist, but I’m going to guess that microwave, xray,gamma,uv and all sorts of high frequency em radiation at low to high intensity is a bad thing in the long term. How high will the cancer rate go?

  45. tom mac says:

    Reminds me of the story ( true? )about the Scotman that put a coil under the HP-lines running accross this cow pasture… the power company sued him for stealing power. I think they lost the suit

  46. ab says:

    Nevertheless it looks cool.

  47. supaduck says:

    I can’t help but take a look at the picture and think of how much light pollution this “hack project” must have caused, and will cause.

  48. GT says:

    Just to clear things up “the high electric field produced by the power supply is enough to ionize the molecules in the nearby fluorescent tube, which then produces light”. I was doing my physics homework, read this in my book and remembered this post so I thought I would share.

  49. pb says:

    The bulbs add an extra impedance, albeit a small one, to the power lines, causing a dissipation of power beyond what is “leaked” anyway, and is therefore stealing.

    Power companies have actually prosecuted or at the very least tracked down people in the past for doing this, this sort of display is nothing new. There have been stories of people lighting their houses using this concept only to be caught by the power company during random field inspections.

  50. watch movies says:

    “Well it probably wouldn’t move even if you put it right next to the wire since it is an AC field.”

    there is a push towards dc transmission lines because they are more efficient

    even then, there will be no perceptible variation in the compass…

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