Author Topic: If the electrical energy is outside the wires, how is insulation protecting us?  (Read 9570 times)

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Online RJSV

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Ah, thank you, bsfeechannel.
That explanation provides a way, to start thinking about the electric 'Model' for the two cases of contact.
First case being simple contact, with another contact to a ground, or a second metal conductor.  That's the more 'classic' case, where you can figure out a clear path, unfortunately going through a person, to wet floor etc.
The other situation, RF, my thought is that you could 'touch' the cable wire, but by way of a bunch of capacitors, conducting current easy due to RF high frequency. So, no need to look directly, for a 2nd conductor to contact...the RF can 'find' that 2nd place, where the RF has little impedance, like an insulated shoe bottom, having enough capacitance to put person in danger, and the person's body then is conductor via the tissues and fluids.
  My body model could start there, place a capacitor to ground (wet floor containing steel rebar), and MODEL the body as a resistor, at, say 500 ohms. THEN, on other end, another capacitor, to the cable metal inner wire; that would 'model' the insulation.
   Result looks like CAP--Resistor--CAP and then you run your numbers, at RF frequency.
Skin effect, is too complex for me to lecture on, but I can understand portion of others explanation about RF burns. (I think that's in the skin surface, ...a separate consideration, using same word, as skin effect generally for some surface, like a cup or outside of a RF coax.)
   That model was very simple, but point being RF doesn't necessarily need a visably 'complete' conductor around the circuit, (to convey the burns).
 

Offline SiliconWizard

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Well, when you touch an object, I don't think you're ever in full "contact" with the underlying material at the atomic scale. There are a lot more gaps than points of contact, I think. You're just getting "very close".
 
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Offline TimFox

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When human skin touches a metal object, much of the electrical contact is through water (saline solution in sweat).
At the "atomic scale" (0.1 nm) the electrons move about in the environment.
 

Offline SiliconWizard

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When human skin touches a metal object, much of the electrical contact is through water (saline solution in sweat).

Yes, which is why the impedance directly depends on how dry/wet(/oily...) your skin is.
But that water interface with ions opens a whole other can of worms.
 

Offline TimFox

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Back in high school, we amused ourselves with "lie detection" by gripping the two probes of a Simpson 260 on its highest megohm scale:  the resistance varied considerably depending on the skin moisture content.
 

Offline aetherist

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When human skin touches a metal object, much of the electrical contact is through water (saline solution in sweat).
At the "atomic scale" (0.1 nm) the electrons move about in the environment.
What i reckon happens is that elektons jump from the surface of the metal & into the water where they then become orbiting photons orbiting the water nuclei (the orbiting photons are wrongly called electrons), ie creating ions (negatively charged water molecules), & these ions drift slowly along through the water (at say 1 mm/s). However, the drifting ions create an electric current, & this current has a wavefront propagating very fast through the water (at say c/100).

Hence the electricity found flowing through water is similar to the old (electron) electricity which supposedly flows along a wire. But in the case of water the drifting ions idea (of electricity) is correct. Whereas in a wire the drifting electrons idea (of electricity) is wrong.

Electrons do not orbit nuclei, photons (elektrons) orbit nuclei. 
Electrons are photons that have formed a loop by biting their own tail. 
Electrons are photons that orbit nothing, they go round & round, but don’t orbit anything physical. In that sense an electron is free to move, albeit as directed by its own negative charge.
An orbiting photon is not free to move. Except that a conduction elektron is free-ish i suppose.
We all call it a conduction elektron, praps a conduction photon duz take the form of an electron when it breaks free of the nucleus , in which case they are indeed conduction electrons.
Free surface electrons are almost certainly electrons. Still thinking.
« Last Edit: April 29, 2023, 11:06:43 am by aetherist »
 

Offline TimFox

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This reads more like mythology than physics, especially the tail-biting.
Remember that ionic solutions have substantial conductivity.
The relationship between electric field E and current density J in a conductor is J = (sigma)xE, where E and J are vectors (Ohm's Law).
In an isotropic medium, "sigma" is a scalar, but in an anisotropic conductor (e.g., graphite), it is a tensor.

Drifting electrons in a metal or semiconductor (rather important for electronic engineering):
At normal field values within the metal, the charge carriers do not accelerate in the same manner that they accelerate between cathode and anode of a cathode-ray tube, but they reach a terminal velocity (due to scattering from impurities and other solid-state physics phenomena) that is proportional to the E field.  (At very high fields, the proportionality breaks down.)
The Hall effect is useful here:  it can differentiate between electrons moving one way and holes (positive charge carriers) moving the other way, even though the electrical current is in the same direction, and shows that charge carriers within a conducting metal wire are, in fact, electrons.  (Both types of charge carriers occur in semiconductor devices.)
« Last Edit: April 04, 2022, 10:35:20 pm by TimFox »
 

Offline aetherist

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This reads more like mythology than physics, especially the tail-biting.
Remember that ionic solutions have substantial conductivity.
The relationship between electric field E and current density J in a conductor is J = (sigma)xE, where E and J are vectors (Ohm's Law).
In an isotropic medium, "sigma" is a scalar, but in an anisotropic conductor (e.g., graphite), it is a tensor.

Drifting electrons in a metal or semiconductor (rather important for electronic engineering):
At normal field values within the metal, the charge carriers do not accelerate in the same manner that they accelerate between cathode and anode of a cathode-ray tube, but they reach a terminal velocity (due to scattering from impurities and other solid-state physics phenomena) that is proportional to the E field.  (At very high fields, the proportionality breaks down.)
The Hall effect is useful here:  it can differentiate between electrons moving one way and holes (positive charge carriers) moving the other way, even though the electrical current is in the same direction, and shows that charge carriers within a conducting metal wire are, in fact, electrons.  (Both types of charge carriers occur in semiconductor devices.)
Yes. I wasn’t sure how to break it to u. That electrons don’t orbit nuclei. The orbiting is done by photons.
However, u will be pleased to know that free electrons do exist.

Orbiting photons solves a deep mystery that used to keep me awake at night. How can an orbital electron absorb the energy of a photon, & then re-emit that photon. The simplest solution is that the photon is absorbed by an orbiting photon. Or is not absorbed at all but merely joins its mates.  First the elekton. Now the orbiting photon. U can't stop genius.

I think that drifting elektrons might exist in a metal. Here the orbiting conduction photons might have to break free & form free electrons by biting their own tails, at least briefly. I think that that could happen on the surface of the metal, but praps inside also. I can go along with that. But, electrons do not orbit nuclei.

Ok everybody sit down & stay calm & listen. There is no need to panic. Electricity is safe. Here is a summary.
Photons can exist in many ways.
(1) Free photons (zero charge in the far field).
(2) Elektons (photons hugging the surface of a metal)(negative charge).
(3) Orbiting photons (elektrons hugging a nuclei instead of the surface of a metal)(negative charge).
(4) Electrons (photons that have formed a loop)(the photon orbits around nothing)(negative charge).
(5) Positrons (positive charge)(electrons that are twisted inside out).
(6) Neutrinos (pairs of photons sharing the same helical axis)(zero charge in the near field & in the far field)
(7) Positons (positive charge)(elektrons that are twisted inside out).
(8 ) The photon is the building block for all elementary particles (quarks, muons etc)
« Last Edit: April 29, 2023, 11:09:47 am by aetherist »
 

Offline TimFox

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The straw horse of "orbiting electrons", such as seen in graphics for atomic energy organizations, is not to be taken literally in the sense of the Moon orbiting the Earth.  The first quantum explanation of atomic structure by Neils Bohr gave some reasonable results, but there has been a lot of work done in the last century.
Have you ever studied quantum mechanics?  The proper discussion of atomic structure is not easily found in comic-book illustrations, but the modern theory predicts spectroscopic results to incredible accuracy.
For example, the "Lamb shift", the energy difference between the two states 2S1/2 and 2P1/2, which would be equal by simple quantum mechanics, was explained by later QED (quantum electrodynamics) and the predicted value of only 1057.864 MHz agrees with measurement to 1 ppm or so.
This article gives more than you want to know about this phenomenon:  https://quantummechanics.ucsd.edu/ph130a/130_notes/node476.html
« Last Edit: April 04, 2022, 10:55:11 pm by TimFox »
 
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Offline aetherist

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The straw horse of "orbiting electrons", such as seen in graphics for atomic energy organizations, is not to be taken literally in the sense of the Moon orbiting the Earth.  The first quantum explanation of atomic structure by Neils Bohr gave some reasonable results, but there has been a lot of work done in the last century.
Have you ever studied quantum mechanics?  The proper discussion of atomic structure is not easily found in comic-book illustrations, but the modern theory predicts spectroscopic results to incredible accuracy.
For example, the "Lamb shift", the energy difference between the two states 2S1/2 and 2P1/2, which would be equal by simple quantum mechanics, was explained by later QED (quantum electrodynamics) and the predicted value of only 1057.864 MHz agrees with measurement to 1 ppm or so.
This article gives more than you want to know about this phenomenon:  https://quantummechanics.ucsd.edu/ph130a/130_notes/node476.html
I don’t know enough (math etc) to be able to study Quantum stuff, so i don’t understand any of it.
But i know that some scientists don’t like the idea of an atom having a nucleus, & some don’t like the idea of electrons orbiting a nucleus.
I think that atomic energy is a safer term than nuclear energy.
Some scientists don’t like the idea of electrons. They might concede that there is a kind of electron effect, but that it is due to rolled up em radiation or somesuch (which aint far from my "biting its own tail")
Jeans said that matter was bottled light.
I don’t like all of the theoretical particles & virtual particles demanded by Quantum stuff.
 

Offline TimFox

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"You're the expert, but a lotta guys..."
 
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Offline typoknigTopic starter

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So, rhetorical question, is "current" a measure of energy?  Since the answer is "yes", how is it that a 10 AWG solid core wire will carry more amperage than a 10 AWG stranded wire, yet the stranded wire has more surface area?
 

Offline TimFox

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No, "current" is not a measure of energy.
In normal electrical units, the "watt-second" is energy, usually referred to in physics as the "Joule".
 

Offline TimFox

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"I don’t like all of the theoretical particles & virtual particles demanded by Quantum stuff."

Another in a series of arguments by several posters that they find something to be "icky" and therefore refuse to deal with it.
 

Offline T3sl4co1l

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Current is a measure of energy in the sense that it's energy per flux (volt-second).  You wouldn't say that a displacement, or a force, is a measure of energy, any more than one is contingent on the other: their product (given a few others conditions) being energy.  Or velocity being more analogous to current, the product with potential being power, hence needing time to get energy from voltage and current.

So for example, the say 6AWG or so wires used for overhead power lines -- these might be good for 50A in in-wall electrical wiring, which at 120/240V is merely 6/12kVA capacity.  Up on the poles, with free air and ceramic insulators, it takes more current for the same temperature rise, or they may be allowed to run hotter besides, and so distribution lines might run 100A.  Carrying 4800V or more, you get capacity upwards of half an MVA quite easily.

Meanwhile, even though the current and thus voltage drop might be higher, the fact that the system voltage is 20+ times higher, means the voltage drop is 10+ times smaller in relative terms, thus the transmission efficiency is extremely high, suitable for distances of tens of miles.

This says nothing of stranded; for mains purposes, there's no difference, the wire is jacketed and the jacket is only slightly larger for stranded, so its temp rise is hardly different.  At low frequencies (DC and mains, except for the largest conductors), current flows in the entire cross-section, which is equivalent (they're both called "6AWG" for a reason).

There is some truth to the assertion at higher frequencies, however.  Skin effect forces current to flow on the surface of the conductor.  A stranded 6AWG wire might have say 10-20% less AC resistance at, oh, a few kHz, compared to solid.  It's not much, but it is something.  Even better if the strands are fine and individually insulated (litz), in which case the cable might have AC resistance not much higher than DCR, even at a few 100 kHz (where the solid wire is naught but a thin tube, electrically speaking).

(The largest transmission lines use conductors the size of your forearm, typically using aluminum for lighter weight, built around a steel core for strength.  The build is stranded for flexibility, which again also increases the skin depth somewhat; but again, this is a small difference, and when quite high currents are required (several thousand amperes), multiple conductors are used in parallel, spaced out a bit so that their magnetic fields don't affect each other quite so much (proximity effect, basically skin effect but for strands a bit further apart from each other).  The increased effective diameter of the bundle also reduces electric field and thus corona discharge -- these are very high voltages indeed, pushing a megavolt.  Such lines can transmit the power of whole power stations (gigawatts), or indeed some entire countries.)

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Offline TimFox

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Even at 60 Hz, skin effect can have a measurable effect on the electrical loss in copper for diameters exceeding, say, 20 mm (500 mcm).
At twice that diameter (2000 mcm copper wire), the resistance at 60 Hz increases by about 23% over that at DC.
« Last Edit: April 07, 2022, 04:58:54 pm by TimFox »
 
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Offline aetherist

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So, rhetorical question, is "current" a measure of energy? 
Since the answer is "yes", how is it that a 10 AWG solid core wire will carry more amperage than a 10 AWG stranded wire, yet the stranded wire has more surface area?
1. Do tests show that a solid core will melt (or something) at more Volts than a stranded? 2. Is this for Cu? 3. Is this for DC? 4. Is this for bare wires (ie not insulated)? 5. Is your question aimed at my new (elekton) elekticity theory? If my 5 questions all get a YES, then i might be able to answer your question (in my usual amateurish way).

I suspect that for the same Voltage stranded will result in more Amps, koz it has less resistance than solid.
And if heat loss depends on  I*I*R then stranded  will produce more heat than solid.
U said that solid will carry more amps, but i will ignore that.
If the R of stranded is 9, & solid is 10, & V is 100, then I in stranded is 11, & I in solid is 10, & heat in stranded is 11*11*9, which is 1089, & heat in solid is 10*10*10, which is 1000.
Hence the stranded will/might melt before the solid melts.

Another way of looking at it (depending on how the question is framed). Stranded wire might not carry as much voltage as solid (in some circumstances), koz if the stranded has sharper bends (somewhere along the line) then elektons are more likely to jump away from the stranded & not return, this loss of elektons problem being magnified by the rougher surface of stranded.
« Last Edit: April 29, 2023, 11:11:28 am by aetherist »
 

Offline aetherist

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"I don’t like all of the theoretical particles & virtual particles demanded by Quantum stuff."

Another in a series of arguments by several posters that they find something to be "icky" and therefore refuse to deal with it.
Can quantum stuff explain how insulation prevents electrocution?
Can quantum stuff explain my new (elekton) elekticity, ie can it explain how a photon can be constrained in 2 dimensions (ie on a surface), ie can it explain that a photon can hug a wire?
« Last Edit: April 29, 2023, 10:53:18 am by aetherist »
 

Offline TimFox

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"I don’t like all of the theoretical particles & virtual particles demanded by Quantum stuff."

Another in a series of arguments by several posters that they find something to be "icky" and therefore refuse to deal with it.
Can quantum stuff explain how insulation prevents electrocution?
Can quantum stuff explain my new (electon) electricity, ie can it explain how a photon can be constrained in 2 dimensions (ie on a surface), ie can it explain that a photon can hug a wire?

1.  Quantum solid-state physics describes how insulators work and differ from conductors, so the answer is yes.
2.  Quantum stuff cannot explain nonsensical theories with no experimental evidence to back them, so the answer is no.
 
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Offline typoknigTopic starter

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No, "current" is not a measure of energy.
In normal electrical units, the "watt-second" is energy, usually referred to in physics as the "Joule".

An excerpt from Wikipedia's Electrical Energy article:  "Electrical energy is energy derived as a result of movement of electrically charged particles."
An excerpt from Wikipedia's Electric Current article: "An electric current is a stream of charged particles, such as electrons or ions, moving through an electrical conductor or space."

By those definitions and, I would argue, any common definition of "energy", current must be considered energy.  Sorry if I'm being thick Tim (I really want to understand this, that is why I keep asking questions about things that don't seem to jive), but what is it about the definition of energy that makes it not apply to the definition of current, based on your understanding?
« Last Edit: April 08, 2022, 05:26:29 am by typoknig »
 

Offline T3sl4co1l

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In a colloquial sense, it's things in motion; having energy.  But that's different from an amount of energy in joules or whatever.

Have you dome intro physics, mechanics?  Definition of position/velocity/acceleration, Newton's laws, etc.?  That's a good place to start.

Tim
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Offline TimFox

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No, "current" is not a measure of energy.
In normal electrical units, the "watt-second" is energy, usually referred to in physics as the "Joule".

An excerpt from Wikipedia's Electrical Energy article:  "Electrical energy is energy derived as a result of movement of electrically charged particles."
An excerpt from Wikipedia's Electric Current article: "An electric current is a stream of charged particles, such as electrons or ions, moving through an electrical conductor or space."

By those definitions and, I would argue, any common definition of "energy", current must be considered energy.  Sorry if I'm being thick Tim (I really want to understand this, that is why I keep asking questions about things that don't seem to jive), but what is it about the definition of energy that makes it not apply to the definition of current, based on your understanding?

"Energy" is a defined term in physics, and I follow that definition.  As an example, the velocity of an automobile is not its energy.  The kinetic energy of the automobile is E = (1/2)mv2, which depends on both the mass m and the velocity v.  Increasing the velocity increases the energy, but is not the energy itself.  This is careful, not pedantic, usage of the word "energy".  In popular usage, breakfast cereal gives a child "energy", but that is not scientific usage.
 

Offline T3sl4co1l

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And to be clear -- I don't mean to patronize or belittle, I honestly don't know your education level so don't know where to start.  Energy is an abstract concept, it's not trivial to understand; it takes time and care to develop.  It's a sizable part of the relevant HS/college level classes, for good reason!  And well worth reading up on, if you haven't worked with it before (or in a while; a refresher is always welcome, too!).

Not sure what the best resources are these days; there's always Wikipedia and Hyperphysics, though they have the downside of tending to present information from within the domain itself, so aren't always that approachable from the outside.

Tim
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Offline typoknigTopic starter

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No, "current" is not a measure of energy.
In normal electrical units, the "watt-second" is energy, usually referred to in physics as the "Joule".

An excerpt from Wikipedia's Electrical Energy article:  "Electrical energy is energy derived as a result of movement of electrically charged particles."
An excerpt from Wikipedia's Electric Current article: "An electric current is a stream of charged particles, such as electrons or ions, moving through an electrical conductor or space."

By those definitions and, I would argue, any common definition of "energy", current must be considered energy.  Sorry if I'm being thick Tim (I really want to understand this, that is why I keep asking questions about things that don't seem to jive), but what is it about the definition of energy that makes it not apply to the definition of current, based on your understanding?

"Energy" is a defined term in physics, and I follow that definition.  As an example, the velocity of an automobile is not its energy.  The kinetic energy of the automobile is E = (1/2)mv2, which depends on both the mass m and the velocity v.  Increasing the velocity increases the energy, but is not the energy itself.  This is careful, not pedantic, usage of the word "energy".  In popular usage, breakfast cereal gives a child "energy", but that is not scientific usage.

Can you provide a reference to the physics definition?  I'm assuming you are saying it doesn't match the definition provided in the Wikipedia articles I referenced?  I dusted off my physics book (Cutnell & Johnson Physics, 6th Edition, (C) 2004) and its definition can be seen in the attached picture.

I guess I could maybe see how someone could/would not consider current "energy" by this definition since it is the field causing the particles to move, but I think it is a stretch.  Once the electrons are moving, they have had "some" energy imparted to them, so even if the field is what caused them to move in the first place, if the field is removed there will be some span of time (short as it may be) that the electrons will still be flowing, correct?
« Last Edit: April 08, 2022, 06:34:16 pm by typoknig »
 

Offline IanB

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Can you provide a reference to the physics definition?  I'm assuming you are saying it doesn't match the definition provided in the Wikipedia articles I referenced?

The definition of energy is fundamental, and is addressed in any introductory physics or thermodynamics text. This is not an area where Wikipedia should be a primary reference (all Wikipedia articles have to refer to primary sources for any facts they give, so you might consider following the references to primary sources given in Wiki articles).

It is, incidentally, the case that nobody really knows what energy "is". It is simply a quantity that has been observed through countless experiments to be conserved, and which obeys various rules that also have been determined by experiment. There is no intuitive way to say that the thermal energy in a hot cup of coffee is the same "stuff" as the chemical energy stored in a battery, but experimentally it is proven to be the case.
 


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