funky SEC splice

[Kristi Silber]

This should be a nice, simple question, I just want to be sure of myself, being electrically ignorant as I am. To me this looks wrong. Not just the wire nut splices, but the intermediate cable - too small for 150A service, right?

Incidentally, this home had an internal surge while hubby was installing a ceiling fan that fried the panel and first floor receptacles. Shouldn't the CB protect against that? I don't quite understand what happened.

[Jerry Peck]

Someone replaced the service equipment, riser, and weatherhead, and who know what else. When they installed the new mast they raised the weatherhead, possibly for better clearances (was below the window, raised it to above the window) - problem is, though, that they did not call the power company for a disconnect/reconnect, and because they could not replace the overhead service lines themselves, they just ran some cable from the overhead service up to the new weatherhead. Thus the end result is that they did not accomplish anything regarding increasing the clearances - the overhead service drop is still below the window.

Yeah, those blue wire nuts are not allowed for that and the power company would not do that, but not much else they did looks good either ... other than good intentions.

[Kristi Silber]

But check out the cable they used to run from one splice to the other. It's not normal SEC cable. To me it looks small (2nd photo, you can see the individual wires connecting to the nuts) - maybe 10 ga. tops? Is that enough?

[Kristi Silber]

Oh, sorry, didn't see Robert's post before my last one. That would explain it, since they just got a new panel installed not long ago. Probably noticed the clearance problem and figured they'd bring it up to code. Thanks!

[Garry Blankenship]

Funky indeed. Looks to me like both you and Robert are correct. While it hopefully is temporary, your right about that extention wire being too small. It does look like 10/3 NM cable. Even if you could rate it as in free air it is too small for a 150 to 200 amp service. Not to mention a lot of wire strands had to be trimmed off the utility cables to get a blue wire nut on there.

[Jerry Peck]

Not to mention a lot of wire strands had to be trimmed off the utility cables to get a blue wire nut on there.

None needed to be trimmed off to fit the blue wire nuts on ... I know 'cause after Hurricane Andrew I had to do a temporary re-connection at my brother-in-law's house down in Miami. We were out working on other jobs and did not get to replace his service equipment and riser that Andrew took down, we missed FPL coming by to hook his neighborhood back up, so I had to make a temporary connection myself - took FPL another month of two before they were back in his neighborhood and hooked it up properly. I only connected it that way because of the extreme conditions left after Hurricane Andrew said hello and good bye.

[Corey Friedman]

It does look small even for a cable in free air. The existing conductors appear to be in the range of #2 which would make the original service about 100 amps. You would need to know the connected load to be sure that the cable won't burn up.

If this is temporary due to a service upgrade (which is what it looks like) the temp wires will be just fine. This set up is extremely common for a service upgrade.

Corey

[Kristi Silber]

Not a service upgrade, but a panel replacement; temporary, at any rate (hopefully!). Not too worried about it now.


It does look small even for a cable in free air. The existing conductors appear to be in the range of #2 which would make the original service about 100 amps. You would need to know the connected load to be sure that the cable won't burn up.

That's a bit beyond my purview, I'm afraid. I do insurance inspections, not regular home inspections, and load calculations are far beyond the scope of the surveys. I doubt many field reps even pay attention to the SECs.

I forgot about my second question myself until just now. Maybe I should have put it in another thread, but anyway - what would cause an internal surge - touching the hot and neutral together? Shouldn't that trip the breaker?

(And this may seem like a really dumb question, but I was debating it with a friend. I'm embarrassed to even give it its own thread. The current flows out through the hot and back through the neutral, right? My friend was saying it didn't really matter whether neutral and hot were reversed when hooking up a light fixture. My instinct says it may still work but it's wrong anyway. I've been looking for a satisfactory answer, and some stuff I've read supports my view, but I still would like someone's opinion. For some reason I'm sort of brain dead when it comes to electricity.)

[Garry Blankenship]

There are no dumb questions. We're all hear to learn, ( a reasonably close quote to a not too long ago Robert Meier post I read ). "Internal surges" can be caused by many sources. A short in the home, a utility line short/problem, lightning and today we have new mysteries manifesting in the form of RFI, ( Radio Frequency Interference ) and EMI ( Electro-Magnetic Intereference ) which includes cell phone towers and other "air wave" frequencies that can be induced into regular power lines. Sounds like the "hubby" shorting something out while working on that fan is the likely culprit. Electricity is so amazingly fast that our brains struggle to understand it's characteristics. Circuit breakers are made by us imperfect humans and in tiny fractions of a second some will pass more "surge" than others. Polarity and where power goes to or from gets confusing when AC, ( alternating current ), is involved. DC, ( direct current ), flows from positive to negative, is very linear in nature and our brains digest it well. AC current alternates back & forth, ( in North America 60 times in one second ), and that makes the to and from part much harder to comprehend. Your instinct is right. Reversing polarity, things may still work, but, ( like Robert pointed out ), things designed/expected to be grounded become hot and visa-versa. A very dangerous situation. Too much rambling ?

[H.G. Watson, Sr.]

AC doesn't actually "flow" in one direction like a simple DC circuit.

Opening (switching) the neutral or the grounding conductor is a no-no.

Mistaking switch loop conductors for circuit conductors or vice versa is a common DIY error - as is not understanding that power from the panel may be at the fixture or the switch box.

[Ken Lyons]

That looks like #6, posibly range wire. I wouldn't want to put more then 60 amps on it but it lets the homeowner use the lights and small items. I'd say okay for temp but needs a breaker to limit current to avoid the wires from overheating and burning on the side of the house.

Like Peck, I've had to do many repairs after hurricanes...worst was when a tree went down on a yard that entrapped the SEC/overhead... tree people wouldn't get the huge tree till the SEC was secure.. power company won't go in till the tree is out of the way... so yours truely, in full protective gear, had to go hunting for it, wirenut/tape and untangle the overhead line from the tree. Split bolts are a better method, if crimps are not available, many will pass a temp split bolt during final.

[Kristi Silber]

No, not too much rambling Garry, great answer! Thank you all! I think one reason I got confused is because people often use the analogy of flowing water to describe amps, volts and watts. Even the word “current” is a little misleading.

So if a light socket is wired correctly, I won't get shocked by touching the threads because I'm less conductive than a wire that is grounded, but if it's hot (and I'm barefoot in a puddle, say) then I become the ground. Is that correct?

[Tom Rees]

Could those smaller wires spliced in be for free power, say to an A/C unit.

[Billy Stephens]

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Could those smaller wires spliced in be for free power, say to an A/C unit.
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The ones at the Top Go Nowhere at All.
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[Billy Stephens]

Could those smaller wires spliced in be for free power, say to an A/C unit.


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The ones at the Top Go Nowhere at All.
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The small cable connects the conductors out of the weatherhead at the top to the existing drop at the bottom.
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So what does the small cable wires feed ? :rolleyes:
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[Stephen G]

Since that mast looks like it came in a bunch of segments, could you just kill power at the drop, lower the existing high mast to XXX above the drop and cut to length etc???

with permission this time... :D

[Billy Stephens]

The service was raised form the utility drop at the bottom to the new weatherhead location at the top. Since the utility power is being fed to the bottom a small cable has been run to the weatherhead to provide power to the service. The cable is attachted to the EMT and simply connects the two points together temporarily. This is a very common setup.

http://www.inspectionnews.net/home_inspection/attachments/electrical-systems-home-inspection-commercial-inspection/26222d1342482922-funky-sec-splice-sec-mast.jpg
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Robert,

The Cables at the top Feed Nothing ( no power usage )but are just spliced to the current incoming service connections.
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Tom's question were there any theft of power service.
*please see post # 16
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[Jerry Peck]

The Cables at the top Feed Nothing ( no power usage )but are just spliced to the current incoming service connections..
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Billy,
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I would lend you my glassed, but you are too far away to reach ...
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The overhead service IS STILL coming in at the lower level ...
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... and is connected to that NM cable which goes up to the conductors you are referring to ...
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... and THOSE conductors are going down the new mast and feeding the entire house.
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I.e., those conductors ARE being used.
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[Gunnar Alquist]

I know 'cause after Hurricane Andrew I had to do a temporary re-connection at my brother-in-law's house down in Miami.

WAITAMINNIT!!! Did I just read that correctly? JP did something that wasn't to code?!?!? :eek:

I feel faint... I have to sit down! ;)

[Billy Stephens]

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Billy,
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I would lend you my glassed, but you are too far away to reach ...
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The overhead service IS STILL coming in at the lower level ...
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... and is connected to that NM cable which goes up to the conductors you are referring to ...
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... and THOSE conductors are going down the new mast and feeding the entire house.
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I.e., those conductors ARE being used.
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ie. Semantics

If those spliced cables were not there would the house still have power?

Are the conductors Hot ? Yes are the conductors Necessary to provide Service ? No .

Are you taking Post 17 out of context from Post 16 ? :rolleyes:

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[Billy Stephens]

What does semantics have to do with it? Jerry wanted to offer you his glasses because you're either not looking closely at the photo or not reading the multiple explanations of this simple installation or both.
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Yeah Thanks. :rolleyes:
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[Kristi Silber]

Since that mast looks like it came in a bunch of segments, could you just kill power at the drop, lower the existing high mast to XXX above the drop and cut to length etc???

with permission this time... :D

You could, but that would negate the whole reason for raising the weatherhead in the first place (presumably) - to make it more than 3 feet from an opening window, thereby bringing it up to code.


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ie. Semantics

If those spliced cables were not there would the house still have power?

Are the conductors Hot ? Yes are the conductors Necessary to provide Service ? No .

Are you taking Post 17 out of context from Post 16 ? :rolleyes:

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I don't understand what you're getting at, or why you used the "sarcasticon" in your last post. If you took away any section of the conductors shown, the house would lose power. There is no stealing of power here for the A/C or anything else.

It must be my photos that are the problem. Below the bottom drip loop there are no conductors visible.



That looks like #6, posibly range wire. I wouldn't want to put more then 60 amps
on it but it lets the homeowner use the lights and small items. I'd say okay for
temp but needs a breaker to limit current to avoid the wires from overheating
and burning on the side of the house.

This is an interesting point. We've had a lot 100 or near 100 degree days here lately, and the A/C is probably running most of the time. A lot of people around, fair size house. I wonder if they know to be careful about it.

[Garry Blankenship]

No, not too much rambling Garry, great answer! Thank you all! I think one reason I got confused is because people often use the analogy of flowing water to describe amps, volts and watts. Even the word “current” is a little misleading.

So if a light socket is wired correctly, I won't get shocked by touching the threads because I'm less conductive than a wire that is grounded, but if it's hot (and I'm barefoot in a puddle, say) then I become the ground. Is that correct?

In a word - - - yes. Like water, power always will take the path of least resistence to get back "home". Utility companies provide a / the reference to ground. They actually use the ground as a return or circuit completion conductor. Even if the individual house service has not been grounded, the power still wants to get to ground, but it needs a path. The air has to much resistence, so the power is just there waiting like pressurized water at a closed valve. When Kristi touches the hot and then touches the ground, via the toes in water, you have provided a path for the power to get where it wants to go - - - unfortunately through you. You can touch a hot wire and nothing will happen, if there is no path from the rest of you to ground. However; when touching a hot wire, if any part of your body touches something grounded - - - problemo. Like the birds on the utility wires, you can do chin-ups all day long on a bare utility wire with impunity, but get too close to a return wire or ground and you'll get roasted.

[Ken Lyons]

It must be my photos that are the problem. Below the bottom drip loop there are no conductors visible.



For those not sure. First (tall) photo shows two untility anchors on the side of the house, top one has a brand new weatherhead with SEC cable going to a brand new panel. The bottom achor currently has the overhead line from the utility pole. Between the two anchors is an almond cable, that appears to have #6/2 wire. In the tall photo you can clearly see the top connection is wirenutted to the cable, in the (second) photo you can see the black and red (thin wires) wire nutted to the utility line, and the netural nut is visible but can't see the conductor. -- This appears to be a temp arrangement to feed power to the new service until the utility moves their line to the upper achor point and does a proper splice to the new weatherhead. --zoom on the bottom wirenuts to to see the condutors.

[Dave Ruth]

In a word - - - yes. Like water, power always will take the path of least resistence to get back "home".
I suspect that power will follow all paths home in proportion to resistance of each path.

[Jerry Peck]

In a word - - - yes. Like water, power always will take the path of least resistence to get back "home".

More correctly stated, electricity, like water, will take ALL AVAILABLE paths, not just the path of least resistance. While most water and electricity will take the path of least resistance, there will be A LOT of electricity and water taking any and all other available paths. ;)

[Kristi Silber]

It seems like the key phrase is "in proportion to resistance." That would mean that two appliances with different resistances could still get power, they just wouldn't get the same amount.

It's no wonder that I was (am still!) confused by AC electricity when words like "flow" and "current" are used. It seems to me that there must be movement of energy along wires, even with both positive and negative pulses at 60 hertz. Even if the net charge over one cycle is zero, the majority of the time there is positive or negative excitation of the electrons which would pass from electron to electron through the wire. So you turn on the electricity at one end of a wire, and it takes time for the electrons to transmit the energy along the wire - thus there is movement of energy, even if there's no net movement of each electron. Electromagnetic energy flows just as light does, and also like light has a velocity. The filament of an electric bulb doesn't care which way the energy is flowing, so that no matter which end the hot is hooked up to, energy will flow into it and through it. Because of the resistance of the filament due to it's small diameter and component materials, it heats up and lights up, and some of the energy is lost. Everywhere along the circuit where work is performed and energy is lost makes that an energy sink, so the energy continues to flow. Well, that's my "current" hypothesis, anyway - now's everybody's turn to tell me which parts are wrong!

When the stream analogy for electricity incorporates the concept of pressure it makes a bit more sense. There's flow rate and flow volume, but it's the difference in pressures that does the work.

[Jerry Peck]

It's no wonder that I was (am still!) confused by AC electricity when words like "flow" and "current" are used.

Kristi,

This may be the easy way to explain electricity: electricity is smoke flowing through the system, and when something bad happens and the smoke escapes ... well, whatever let the smoke out stops working and there is no way to put the smoke back into the system. You need to replaced the smoke-depleted item with a new, smoke-pre-charged item of the same kind, and ... viola! ... it works again. :D

[Jim Port]

In a word - - - yes. Like water, power always will take the path of least resistence to get back "home". Utility companies provide a / the reference to ground. They actually use the ground as a return or circuit completion conductor. Even if the individual house service has not been grounded, the power still wants to get to ground, but it needs a path. The air has to much resistence, so the power is just there waiting like pressurized water at a closed valve. When Kristi touches the hot and then touches the ground, via the toes in water, you have provided a path for the power to get where it wants to go - - - unfortunately through you. You can touch a hot wire and nothing will happen, if there is no path from the rest of you to ground. However; when touching a hot wire, if any part of your body touches something grounded - - - problemo. Like the birds on the utility wires, you can do chin-ups all day long on a bare utility wire with impunity, but get too close to a return wire or ground and you'll get roasted.

Electricity is not trying to get to ground. It is trying to get back to its' source, the transformer. The resistance of earth is too high for it to be a good conductor.

Electricity will flow between two points with a difference of potential between them.

[Billy Stephens]

smoke flowing through the system, and when something bad happens and the smoke escapes ...

there is no way to put the smoke back

You need to replaced the smoke-
.

Say What ? :eek:
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[Stephen G]

negate...your not dropping the mast head? Its right beside the openable window.

fail...not code compliant and there is no question from that pic, it is obvious that the job isnt finished, lets hope they when they are done its moved properly,,



You could, but that would negate the whole reason for raising the weatherhead in the first place (presumably) - to make it more than 3 feet from an opening window, thereby bringing it up to code.





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it.

[Kristi Silber]

negate...your not dropping the mast head? Its right beside the openable window.

fail...not code compliant and there is no question from that pic, it is obvious that the job isnt finished, lets hope they when they are done its moved properly,,

It's a single hung sash, and the weatherhead looks to me to be 3' from the openable part. That's the only reason I can think of for moving it. Mast definitely being raised.

Sorry, Jerry, I don't find the smoke analogy very helpful.

[Jerry Peck]

Sorry, Jerry, I don't find the smoke analogy very helpful.

Guess you missed the " :D "?

[Garry Blankenship]

Electricity is not trying to get to ground. It is trying to get back to its' source, the transformer. The resistance of earth is too high for it to be a good conductor.

Electricity will flow between two points with a difference of potential between them.

Don't entirely agree Jim. The xfmr is grounded at the pole or pad mount, making the source and ground the same place. Earth resistance morphs. Depending on conditions, it can be low or high. After rain low; dry it's high. Area soil content & water tables are also players. Electricity has no regard for location, distance or time. It can and will follow any available path, regardless of depth or course. If it is given a ground reference at it's source, it will use / "try to get to" that ground.

[Jerry Peck]

Don't entirely agree Jim. The xfmr is grounded at the pole or pad mount, making the source and ground the same place.

Nope ... and Jim is correct.

Electricity is *ALWAYS* trying to get back to its source ... *ground* is simply ONE PATH that it will take back to that source.

In your description, the transformer IS "the source", and the transformer's connection to ground simply means that if the electricity cannot, for whatever reasons, get back to it through the conductors, the electricity will take all available paths, including the ground path.


Earth resistance morphs. Depending on conditions, it can be low or high. After rain low; dry it's high. Area soil content & water tables are also players.

This time you are correct, and that is why "ground" ("earth") is not a reliable "conductor" back to the source.


Electricity has no regard for location, distance or time. It can and will follow any available path, regardless of depth or course.

Correct again there, but not here:

If it is given a ground reference at it's source, it will use / "try to get to" that ground.

" it will use / "try to get to" that ground "

No, it will use the ground to try to get to the source, the transformer.

Some will complain that this is all a matter of semantics ;) , and, yes, all conversation is "just a matter of semantics", especially written exchanges such as these: the electricity will not " "try to get to" that ground ", the electricity will use that ground to try to get to its source ... which is connected to that ground ... and thus the ground becomes a path for the electrical current flow to find its way back to the transformer. :)

[Kristi Silber]

AC electricity must flow! It doesn't just move back and forth. Or none of this conversation would make any sense.

I don't understand why electricity will always "try" to go back to its source. It's not animate, it doesn't reason or sense, it doesn't know where the transformer is. It just goes where its physics take it. When it goes to ground it's not trying to find a route to anything, the energy gets dissipated through the earth. The surface area of the ground rod overcomes the high resistance of the earth.

If electricity always tended to go back to its source, it would never leave in the first place. In practical terms, it's "trying" to complete a circuit.

Semantics are important. It helps everyone understand when proper, precise words are used.

Jerry, don't you know by know I was born without a funny bone? Congenital defect. Besides, didn't your mother ever tell you electricity's not a laughing matter? Someone could poke an eye out.

[Jerry Peck]

AC electricity must flow!

It does.


It doesn't just move back and forth.

It does that too.


Or none of this conversation would make any sense.

Now I understand why it does not make any sense to you! :D


I don't understand why electricity will always "try" to go back to its source. It's not animate, it doesn't reason or sense, it doesn't know where the transformer is. It just goes where its physics take it. When it goes to ground it's not trying to find a route to anything, the energy gets dissipated through the earth. The surface area of the ground rod overcomes the high resistance of the earth.

Electricity IS always trying to go back to its source ... it doesn't need to "know" where the transformer is, it WILL try to find it ... when it goes to ground it IS trying to find its route back to its source ... the energy is dissipated through earth as it tries to find its way back to its source, that dissipation is wasted energy and is turned into heat ... we wish the surface of the ground rod would overcome the resistance of the earth, but it doesn't.


If electricity always tended to go back to its source, it would never leave in the first place. In practical terms, it's "trying" to complete a circuit.

Yep, it is trying to complete a circuit, and that circuit is ... back to its source.


Semantics are important. It helps everyone understand when proper, precise words are used.

I could not agree more.


Jerry, don't you know by know I was born without a funny bone? Congenital defect. Besides, didn't your mother ever tell you electricity's not a laughing matter? Someone could poke an eye out.

Yeah, my mother said that, but my father said this is what you do and how it works. :p

You can poke someone's eye out with electricity? :cool: :eek:

Kristy, let's start with a car battery, it has a + and a - terminal, and the electricity does not care which is connected to the car body (which is why old cars, and old British cars for much longer, had + connected to the car body instead of - being connected to the body as we see on almost every (if not every) car today.

So, let's start by connecting the - terminal to the car body and the + terminal to nothing. No electricity flows, nothing works, right?

Now let's connect the + terminal to one terminal on a switch, the other terminal on that switch to one terminal on a headlight, and connect the other terminal of the headlight to the car body. With the switch 'off', no electricity flows, the headlight does not light. Now we will flip the switch to 'on', and the circuit is completed, right?

car body to battery -, battery + to switch (which is on and is effectively like a piece of wire between the two terminals) to the headlight to the car body

The light is on ... until the battery runs down or the headlight burns out.

That is DC, or direct current.

Now comes the tricky part, and you will need to be fast to do this, we are going to switch the battery around so the - and + are connected just the opposite, i.e., the battery + is to the car body and the battery - is to the switch. The light still works, right? (it is still a complete circuit and it is still DC, direct current).

Now for the fast and furious part ... are you with me to this point ... grab the clamp holding the wire from the car body to the battery + in one hand, now grab the clamp holding the wire from the switch to the battery - in the other hand ... ready? Now switch the clamps between the battery + and - , now switch again, and again, faster, and faster ... switch the clamps 60 times a second ... you now have 60 cycle AC (alternating current). And each time you connect the clamps to the battery you have a complete circuit, so each time the headlight will light, and at 60 times a second you will not see the headlight go out, it will appear to stay on.

Got it?

Okay, here is the difference between the above and 60 cycle ac as we know it: the battery trick will work, but you basically have instantaneous 12 volts at each connection to the battery, you have a 60 cycle square wave. However, 60 cycle ac as we know it is a sine wave, not a square wave, instead of 12 volts instantly at each cycle, the voltage rises and falls in a sine wave form, thus, for the same effective useful voltage of the 12 volts dc, ac voltage needs to rise to a peak voltage of 12 x 1.414 = 17 volts (16.968 volts, but I'm rounding the peak voltage off at 17 volts).

Okay, so how does the electricity travel far enough and fast enough to complete the circuit each time you switch from - to + on the battery?

The simple answer is that electricity is the same as the speed of light: 186,282.397 MPH. Except that the simple answer is wrong because that is the speed of light through space and the electricity is traveling through a metal conductor, sometimes restricted (resistance) and is slowed down, nonetheless, though, if the speed of electricity is only 180,000 MPH ... it is still traveling pretty darn fast!

60 cycle per second = 3600 cycles per minute = 216,000 cycles per hour

180,000 MPH / 216,000 cycles = 0.8333 mile per cycle - out and back - (if I did the math correctly) or 0.4166 miles per half cycle - out, but not back -

Added with edit: Me Bad! I used MPH and it is MPS - OOPS! BIG OOPS! That means I was off by a factor of 3600! That means that 0.8333 is actually x 3600 = 2999.88 miles - NOT 0.8333 mile. It also means that 0.4166 is actually x 3600 = 1499.76 miles.

Thus, one would think that if the circuit was longer than 1500 miles long that there could be problems, but ...

This is where the simple answer is wrong and it gets complicated, but the simple complicated answer is that ... the current does not need to make the complete trip out and back to work.

Think of it this way: you have a long line of 10,000 people, and each one walks 30 steps out, then 30 steps back, and they are each carrying a load of energy, and as they walk back and forth some of that energy is being used up, and as the energy is used up the people fall out of line, so the generator has to send new people out to take their place, thus one could say that the line may be 'moving its way around the circuit' due to people dropping out of line (energy being used) and new people getting into the line at the generator end (electricity being generated).

Okay, maybe that is confusing, but the complicated answer cannot be answered here.

If what I posted is understood ... well knock me down with a straw, I will be that surprised. :cool:

[Garry Blankenship]

[quote=Jerry Peck;203456]Nope ... and Jim is correct.

Your "nope' is incorrect - - - again. I said the grounding of the transformer makes the source and the ground the same and it does. It's not a nope.
I know, as do most here, Jim is correct about electricity trying to return to it's source. He said it was not trying to get to ground which is why I did not "entirely" agree. It is both - - - not a nope. The ground reference is another path when it is established and electricity will and does use that ground path. I did not say it was a better path, just a path electricity will seek when that ground reference is established. If the electricity is not seeking ground, why do people get shocked when grounded and touching a hot wire ? At the point where the ground reference is established they, ( the source and ground ) are bonded together and are equal / no difference. If there is no path available via a source conductor , but there is a path available via the ground, it will take the ground path. If the system is not grounded, it is an entirely different situation, but the discussion and premise is a grounded system.

[Rod Corwin]

Electricity is so amazingly fast that our brains struggle to understand it's characteristics. Circuit breakers are made by us imperfect humans and in tiny fractions of a second some will pass more "surge" than others. Polarity and where power goes to or from gets confusing when AC, ( alternating current ), is involved. DC, ( direct current ), flows from positive to negative, is very linear in nature and our brains digest it well. AC current alternates back & forth, ( in North America 60 times in one second ), and that makes the to and from part much harder to comprehend.


Seems to be the only accurate statement so far. :D

[Jim Port]

Garry,

You do not need to be grounded in order to receive a shock. All you need is to be at a different potential than the surface that you are touching. I have been shocked while standing on a fiberglass ladder wearing boots with a rubber sole.

If you want look up step potential to see that you can be shocked by having your feet apart while standing on the ground. The path is up one leg and down the other.

[Garry Blankenship]

Garry,

You do not need to be grounded in order to receive a shock. All you need is to be at a different potential than the surface that you are touching. I have been shocked while standing on a fiberglass ladder wearing boots with a rubber sole.

If you want look up step potential to see that you can be shocked by having your feet apart while standing on the ground. The path is up one leg and down the other.

Copy that Jim. Step potential is something for the Y chromosome to be weary of ;) After sliding off my truck seat to get out I always first hit the door w/ the heal of my hand because the finger tips are too sensative for those static jolts. One of my mentors used to do use his thumb & fore-finger to see, if something was hot - - - foolish, I know, ( a bit of grand standing for the rookie ). What I did not know then was his awareness of any and all possible paths through his body. If it was wet or he was not well insulated he would not do it. Not the same thing, but I do a bike ride around home that takes me under some mondo, humming and/or crackling power xmission lines. While traveling under the lines I sometimes get a shock in my thumb where it jumps the handle bar span between the rubber grip and the plastic shifter. Could not begin to splain the circuitry, but I know it's induced power from the lines above and a spark jumps from my hand to the 1" of uncovered metal handle bar. When there is no ground reference it does get mysterious & unpredictable.

[Jerry Peck]

Electricity is not trying to get to ground. It is trying to get back to its' source, the transformer. The resistance of earth is too high for it to be a good conductor.


[quote=Jerry Peck;203456]Nope ... and Jim is correct.

Jim is correct, you are not.


Your "nope' is incorrect - - - again. I said the grounding of the transformer makes the source and the ground the same and it does. It's not a nope.

Nope, not the same anymore than adding 100 feet of resistive wire to a terminal is the same as the terminal.

You are taking your incorrect statement and trying to make it correct ... and all you are doing is explaining why you are incorrect - "grounding of the transformer makes the source and the ground the same" ... no it does not.


I know, as do most here, Jim is correct about electricity trying to return to it's source.

And to which I said he was correct.


He said it was not trying to get to ground which is why I did not "entirely" agree.

And to which I said you were incorrect. Thank you for pointing out why you were incorrect. If it is the same, as you said and are trying to convince us of, then Jim is incorrect - yet you have stated that Jim is correct.

Your "why I did not "entirely" agree" is why it is incorrect to state "grounding of the transformer makes the source and the ground the same".

Close? Yes. But not the same.

"Close" only counts in horseshoes, hand grenades, and atom bombs (and "close" varies depending on which you are are talking about, "close" in horseshoes is a whole lot closer that "close" in atom bombs).


If the electricity is not seeking ground, why do people get shocked when grounded and touching a hot wire ?

Because there is a ground path back to the transformer. The transformer is grounded for lightning strikes, the service is grounded for lightning strikes, that means there are two ground (earth) connections but no intentional current is planned on going between the two, in fact, NO current is intended to go between the two. If the neutral (grounded conductor) had ZERO resistance, there would be no (or so little as to not be measurable) current flow through the ground (earth). But, alas, the neutral (grounded conductor) does not have zero resistance, so you now have a parallel circuit with two path: 1) a low resistance path through the neutral (grounded conductor); and 2) a much higher resistance path through ground (earth). Thus you will get current flow through both.

You are mixing up "grounded to earth" and "grounded to a fixed neutral point to not allow the neutral to float".

"Grounded to earth" has nothing to do (nothing intentionally to do) with "grounded to a fixed neutral point to not allow the neutral to float". It just so happens that the "grounded to a fixed neutral point" is also the point taken to ground (earth), and that causes problems.

[Jerry Peck]

Kristy,

I thought of a simpler way to explain the electrical current not having to go 'all the way around' the circuit to do work. And, yes, before you say it, all "simple ways to explain" things have shortcomings, drawbacks, and are incomplete.

The set up:
- A garden hose is connected to a to a water wheel device where flowing water turns the wheel, another garden hose is connected to the other side of the device, the other two ends of the two garden hoses are connected to an oscillating pump which pumps one direction on the forward stroke and pumps the other direction on the backward stroke. The pump, hoses and water wheel device are filled with water.

When the pump is turned on (the circuit is switched on) and the pump moves in one direction, the water (current in the circuit) flows in that direction - the water wheel turns; the pump now moves in the opposite direction and the water (current) flows in the opposite direction than it did before - the water wheel turns (just turns in the other direction).

None of the water made a complete circuit around the pump system, the water simply flowed back and forth, yet the water still turned the water wheel.

That's a very basic and simplistic explanation of how the voltage (the pump) changes direction and how the current (the water) changes direction, yet work (the water wheel turns) is done in both direction - even though no current (no water) moves all the way through the entire circuit (through the hoses, etc.) - the current (water) just moves back and forth.

[Kristi Silber]

Jerry, these analogies aren't necessary, but I appreciate your effort. In the case of the water wheel example, it doesn't help me understand anything because there is no net flow, no circuit. I've looked at lots of sites about AC, I've seen dozens of sine waves, I've read about the movement of electromagnetic energy and how it's similar to that of light, seen little animated clips of electrons moving back and forth in a wire. I know about positive and negative voltage in AC, hertz, all that stuff. What I want to know is how the energy flows when the electrons do not. But your hose example illustrates an important point. Each time the pump is started, there is going to be a slight lag time as the pressure moves down the hose. I think this is the key to understanding how electricity can flow while the electrons don't. When the voltage switches from positive to negative there's a tiny lag between every electron as it pushes the next one down the line. The interaction of the electrons when they push and pull each other creates an electromagnetic field which flows through the circuit. (This is my own guess, put together from bits and pieces of stuff I can glean from the 'net and my inconsistent knowledge of physics.)

[Garry Blankenship]

"grounding of the transformer makes the source and the ground the same" ""... no it does not."" OK JP; at the point and only that point where the transformer is grounded / bonded to ground what is the difference in potential between the source and the ground ? "If the electricity is not seeking ground, why do people get shocked when grounded and touching a hot wire ?" ""Because there is a ground path back to the transformer."" But you said I was incorrect in saying " it will use / "try to get to" that ground " So you say that the power does go back to that ground point ~ yet you say I'm incorrect when I say it. I am justifyably confused. ""But, alas, the neutral (grounded conductor) does not have zero resistance, so you now have a parallel circuit with two path"" Parallel circuit ? Two paths ? Would that be anything similar to when I said "It is both - - - not a nope" Your two paths and my both paths are saying the same thing. You just said it correctly and I said it incorrectly :rolleyes:

[Garry Blankenship]

This should be a nice, simple question,

I took only the first seven words of Kristi's O.P. in the interest of irony. The thread seems to be anything but nice and simple, but good fodder.

[Kristi Silber]

Hee hee, it seems like few questions about electricity end up being simple!

As an aside, I read yesterday that sometimes the earth has been used as a return path for power and telegraph signal transmission, so that it was only necessary to run one cable. I thought that kind of interesting.

[Jerry Peck]

In the case of the water wheel example, it doesn't help me understand anything because there is no net flow, no circuit.

There is a net flow - if you were to install a flow meter on each side of the water wheel those flow meters would indeed show what rate the water was flowing at the time it was flowing. And there is a circuit, maybe no complete flow through the circuit, but the circuit is there.

If you saw my edited math showing the speed of light is in mps instead of mph, and that the flow of electrons for one-half cycle at 60 cycles per second, if the circuit is less than 1500 miles long, the electrons would, indeed, flow through the complete circuit within each half-cycle - did you review my edited math based on mps and was it correct?


What I want to know is how the energy flows when the electrons do not.

The electrons do flow, and that flow is measured in amperes.


The interaction of the electrons when they push and pull each other creates an electromagnetic field which flows through the circuit.

The electromagnetic field does not flow through the circuit, the electrons flow through the circuit creates the electromagnetic field around the circuit conductors.

[Kristi Silber]

Jerry, If the same volume water is pumped back and forth for the same amount of time at the same speed, there is no net flow. X+(-X)=0

An amp is a coulomb/sec, not electrons/sec. Very different! Electrons are charge carriers, and the number of electrons in the circuit does not change (which is why your analogy of a bunch of people in line didn't make sense to me. The people (electrons) move back and forth, but don't fall out of line). The charges do change, which is why there's electrical potential. At the beginning of the circuit the electrical potential is high because it's near the source, which is why I disagreed that electricity doesn't always try to go back to its source: at that point it's flowing away from the source, down the potential energy gradient and around the circuit.

From Wikipedia:
"The speed at which energy or signals travel down a cable is actually the speed of the electromagnetic wave, not the movement of electrons. Electromagnetic wave propagation is fast and depends on the dielectric constant (http://en.wikipedia.org/wiki/Relative_permittivity) of the material. In a vacuum the wave travels at the speed of light (http://en.wikipedia.org/wiki/Speed_of_light) and almost that fast in air. Propagation speed is affected by insulation, such that in an unshielded copper conductor range 95 to 97% that of the speed of light, while in a typical coaxial cable (http://en.wikipedia.org/wiki/Coaxial_cable) it is about 66% of the speed of light (http://en.wikipedia.org/wiki/Speed_of_light)...
The drift velocity (http://en.wikipedia.org/wiki/Drift_velocity) deals with the average velocity that a particle, such as an electron, attains due to an electric field. In general, an electron will 'rattle around' in a conductor at the Fermi velocity randomly.[3] (http://en.wikipedia.org/wiki/Speed_of_electricity#cite_note-2) Free electrons in a conductor vibrate randomly, but without the presence of an electric field there is no net velocity. When a DC voltage (http://en.wikipedia.org/wiki/Direct_current) is applied the electrons will increase in speed proportional to the strength of the electric field. These speeds are on the order of millimeters per hour. AC voltages (http://en.wikipedia.org/wiki/Alternating_current) cause no net movement; the electrons oscillate back and forth in response to the alternating electric field.[4] (http://en.wikipedia.org/wiki/Speed_of_electricity#cite_note-3)"

From this site talking about the speed of electrons (http://c2.com/cgi/wiki?SpeedOfElectrons): "...for a copper wire of radius 1 mm carrying a steady [DC] current of 10 Amps, the drift velocity is only about 0.024 cm/sec!"

[Jerry Peck]

An amp is a coulomb/sec, not electrons/sec. Very different!

Very different? Yes and no. Yes, the ampere is a measure of current flow rated in coulombs/second and not electrons/second, similar to the speed of a vehicle being measured in miles/hour instead of rotations/second for the wheels/tires which are causing the vehicle to move at that rate of speed.

Which way does current flow?
a) From the battery positive, through the circuit, to the battery negative?
b) From the battery negative, through the circuit, to the battery positive?

Answers:
a) This is correct for what is known as "conventional flow".
b) This is correct for what is known as "electron flow".

Electrons, being negatively charged, travel toward the positively charged terminal of the battery from the negatively charged terminal of the battery.

The flow of electrons in the circuit is accompanied by the flow of charges (rather obvious as electrons are negatively charged and that means negative charges are flowing - moving - through the circuit).


Electrons are charge carriers, ...

Precisely! And to be able to measure the movement of charges

And a coulomb is a measurement of those charges moving around the electrical circuit. How are "ampere" and "coulomb" related? The term "ampere" is used to designate the amount of electrical current (made up of electrons moving through the circuit) and one "ampere" is equal to one "coulomb per second" (a measurement of the charges moving through the circuit).

Coulomb - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Coulomb)
- "One coulomb is the magnitude (absolute value) of electrical charge in 6.24150965(16)×1018 protons or electrons."

The coulomb is a measurement of the electrical charges of the electrons, and with the electrical charges moving (which is measured in coulomb/sec), and the movement of those electrical charges are created by the movement of the electrons.

[Kristi Silber]

The term "ampere" is used to designate the amount of electrical current (made up of electrons moving through the circuit) and one "ampere" is equal to one "coulomb per second" (a measurement of the charges moving through the circuit).




But how could you ever have a flow of current in AC if that were the case? Electrons carry charge:

"The particles that carry charge through wires in a circuit are mobile electrons. The electric field direction within a circuit is by definition the direction that positive test charges are pushed. Thus, these negatively charged electrons move in the direction opposite the electric field. But while electrons are the charge carriers in metal wires, the charge carriers in other circuits can be positive charges, negative charges or both. In fact, the charge carriers in semiconductors, street lamps and fluorescent lamps are simultaneously both positive and negative charges traveling in opposite directions.
http://www.physicsclassroom.com/Class/circuits/u9l2c8.gifBen Franklin, who conducted extensive scientific studies in both static and current electricity, envisioned positive charges as the carriers of charge. As such, an early convention for the direction of an electric current was established to be in the direction that positive charges would move. The convention has stuck and is still used today. The direction of an electric current is by convention the direction in which a positive charge would move. Thus, the current in the external circuit is directed away from the positive terminal and toward the negative terminal of the battery. Electrons would actually move through the wires in the opposite direction."



(http://en.wikipedia.org/wiki/Coulomb)Coulomb - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Coulomb)
- "One coulomb is the magnitude (absolute value) of electrical charge in 6.24150965(16)×1018 protons or electrons."


(http://en.wikipedia.org/wiki/Coulomb)

This is about an inherent property of electrons, not about the charge they can carry. Otherwise, anything with a given number of electrons would have the same charge regardless of what happened to it, and that's clearly not the case. A balloon rubbed up against a sweater is charged, but that doesn't mean it lost or gained electrons.

This site (http://www.physicsclassroom.com/Class/circuits/)is the best I've found for explaining electricity.

[Jerry Peck]

But how could you ever have a flow of current in AC if that were the case?

Because, as you quoted below, the electrons carry the charge, and they move (flow) through the circuit, as in your quote, and their movement is accompanied by the movement of their charge, which is what is quantified in by the coulomb as being one coulomb per second, which is equal to one ampere.

[qutoe]Electrons carry charge:

"The particles that carry charge through wires in a circuit are mobile electrons. The electric field direction within a circuit is by definition the direction that positive test charges are pushed. Thus, these negatively charged electrons move in the direction opposite the electric field. But while electrons are the charge carriers in metal wires, the charge carriers in other circuits can be positive charges, negative charges or both. In fact, the charge carriers in semiconductors, street lamps and fluorescent lamps are simultaneously both positive and negative charges traveling in opposite directions.[/quote]


This site (http://www.physicsclassroom.com/Class/circuits/)is the best I've found for explaining electricity.

It is one of the ones I reviewed recently while trying to address your continued questions of how something happens and your responses that you don't understand.

This is from that site too:
- Electric Current (http://www.physicsclassroom.com/Class/circuits/u9l2c.cfm)

[Garry Blankenship]

But how could you ever have a flow of current in AC if that were the case? Electrons carry charge:

"The particles that carry charge through wires in a circuit are mobile electrons. The electric field direction within a circuit is by definition the direction that positive test charges are pushed. Thus, these negatively charged electrons move in the direction opposite the electric field. But while electrons are the charge carriers in metal wires, the charge carriers in other circuits can be positive charges, negative charges or both. In fact, the charge carriers in semiconductors, street lamps and fluorescent lamps are simultaneously both positive and negative charges traveling in opposite directions.
http://www.physicsclassroom.com/Class/circuits/u9l2c8.gifBen Franklin, who conducted extensive scientific studies in both static and current electricity, envisioned positive charges as the carriers of charge. As such, an early convention for the direction of an electric current was established to be in the direction that positive charges would move. The convention has stuck and is still used today. The direction of an electric current is by convention the direction in which a positive charge would move. Thus, the current in the external circuit is directed away from the positive terminal and toward the negative terminal of the battery. Electrons would actually move through the wires in the opposite direction."



This is about an inherent property of electrons, not about the charge they can carry. Otherwise, anything with a given number of electrons would have the same charge regardless of what happened to it, and that's clearly not the case. A balloon rubbed up against a sweater is charged, but that doesn't mean it lost or gained electrons.

This site (http://www.physicsclassroom.com/Class/circuits/)is the best I've found for explaining electricity.

I'm thinkin J.P. is copy and pasting techno-babble that is a bit beyond his and most all of our understanding. The best analogy I have seen for helping to understand electrical behavior is a pipe full of marbles. The marbles are there / the pipe is already full. Pop a marble in one end and one pops out the other end simultaneously, ( almost ). In the case of DC the marbles are all going in the same end and coming out the, ( other ) same end. In the case of AC the marble insertion alternates from one end to the other, ( 60 times in one second which is even faster than yours truly in some brand new tennis shoes ). Left to right or back & forth; the electron movement creates heat when it encounters resistence. It makes thec resistence in an incandescant light bulb white hot and emit light. Same principal w/ electric wall heater, toaster, clothes dryer or water heater elements. Manufacturing creates just the right amount of resistence to electrical flow to get the amount of heat desired. Flourescent light bulbs have phospherous particles coating the lamp and tiny incandescent elements at both ends. The little elements at both ends emit electrons. The electrons bounce back and forth inside that glass tube 60 times / second. When those electrons collide w/ the phosphor particles light is emitted. Believe it or not, the balloon you mentioned actually does gain or loose electrons. The resistence to their flow is high enough that it only allows a tiny flow, so the ballon will stay stuck / magnetised for quite a while until the tiny electron flow equalizes the charge and it falls.

[H.G. Watson, Sr.]

(I'll probably regret this, but 'I'll give it a whirl':)

When an atom (neutral in its charge, balanced protons to electrons)transfers an electron, the temporary condition (at the time the electron is given up) is a positively charged cation, a condition which is balanced as it acquires/reacquires an electron. Thus a transfer of an electron (negatively charged - thus an ion) from an adjcent atom balances or neutralizes the charge (from its positvely charged condition).

When you retreat back (in your mind) to your elementary/secondary chemistry courses this might "ring a bell", recalling molecular "bonds" made by the "sharing" of electrons.

In the most simplest of explanations: the flow of "electricity", as you know it, is the transfer of electrons; the use of electricity, as you know it, is the "working" of that electromagnetic force (attracting of electrons).

The external circuit (so as to "work" the electricity) vs. the internal "circuit" or the fueled "charge" which is a finite amount of "current" in amps at a specific voltage "electromagnetic force") until electrochemically exhausted or depleated, seems to be what is confusing you. Within the Battery you have a Cathode (positive) and an Anode (negative) - the "flow" internal to the battery to "charge"/recharge/maintain vs. the "working" of electricity (voltage/electromagnetic force) that takes place on an EXTERNAL CIRCUIT - in opposite direction - to "work" electricity: electrons (negative charge) being transfered are "pulled" to the positive charge (opposites attract), as in "pulling current, drawing current", etc.

Thus the use, for example, to slow down galvanic corrosion in a storage type water heater, or other metalic tank containing other than distilled water (i.e. an electrolyte), one supplies and maintains a sacrificial anode, or another example for an underground tank, pipe, etc. one may supply a cathode, and thus "drive" the DC current produced by the corrosion itself(sacrificing the anode) or prevent the corrosion (maintaining a positive "charge" upon the protected tank, pipe, etc.).

Unlike DC or Direct Current; AC or Alternating Current (often designated as a sine wave or waveform), which is what is relevant to household electricity, electron "flow" or exchange, changes "direction" (cycles) 60 times a second (60 Hz) or "pulses" peak to peak - there is no one-way "flow" in AC as "where the positive 'is' and the strength of that positive charge, keeps changing. This is kept in balance by the path "reference to netural" i.e. "center tap" from the transformer or the rectifier.

HTH.

[Jerry Peck]

I'm thinkin J.P. is copy and pasting techno-babble that is a bit beyond his and most all of our understanding.

If Garry had been paying attention to, and reading, the posts, and it is obvious he has not been paying attention or reading them, Garry would have noticed that my explanations begun in simple and simplistic manners and progressed more technical and in depth in response to Kristi's questions progressing into more technical and in depth responses.

Oh, well, I guess some people think they can type relevant posts without having read or paid attention to the previous posts. :rolleyes:

[Kristi Silber]

Garry is right, of course, about static electricity and a balloon giving up electrons. I don't know what I was thinking.

"Flourescent light bulbs have phospherous particles coating the lamp and tiny incandescent elements at both ends. The little elements at both ends emit electrons. The electrons bounce back and forth inside that glass tube 60 times / second. When those electrons collide w/ the phosphor particles light is emitted."

I thought in the case of fluroescence, light is produced when electrons are energized to a higher orbital state around the atom; when they drop back down to the normal state, the energy released is in the form of a photon. Maybe this is just an extension of your electrons colliding with the atoms.

Perhaps I should clarify my main questions:

- how does the force doing the work travel so fast along a wire when the electrons move so slowly, and

- how does the force move at all in AC, a system in which the electrons move back and forth over a short distance.

Unfortunately the Physics Classroom site doesn't seem to go into AC current. For now I'm going with a combination of what you all have said, and adding the electromagnetic field, which does travel fast, as part of the "equation." However, the actual equation is, I believe, a little beyond the scope of the discussion. The field is created by the current (separation of the electrons and protons, i.e. movement of charges), but also influences it, and the waves travel because of the itty bitty interval between charge separation at one point on the conductor and another further along it. I still don't fully understand it all, but perhaps it needs a few days to gel in my mind.

I thank you all for your input. It's been an interesting and educational discussion, and I've learned something from everyone who's taken part.

(Try to be nice to each other even if you disagree!:) )

[bob smit]

Sorry in advance if my post has already been addressed, (no time to read them all):o

The new location is already in violation... the exposed drip-loop is within reach of the window, even without measuring for the 3FT rule.

BTW, I called the U-Co a few years ago for a new triplex drop for a service change. The existing individual drop conductors were near a window anyhow. Since new terminations would be made, I used wire nuts to save me $15.00 smackers as they cut and throw my terminations away, as usual.
The customer called me 3mo & a year later and the U-Co still ignored all my and their calls. I even had CU & AL under those wire nuts.:eek:
Sooo, I spent the money and did it correct.
Still don't know if the U-C0 ever did the replacement. I told the H.O. to call them and say their lights a flickering ETC. Seems only a problem will bring them out.

[Kristi Silber]

I wish now that I'd asked about the new section of mast. Maybe it had nothing to do with window clearance (though you'd think they'd do it to code at any rate!) - maybe it was clearance for something in the neighbor's yard, or the trees next to the house were in the way. I dunno.

Funny the details I didn't see until now. The window casing does seem to indicate that it's double hung. And look where they attached the new insulator to hold the neutral - about 15-18" below the weatherhead, so any drip loop would have to be within 3' of the lower sash. What are they thinking??

[Jerry Peck]

Ran across this and thought it might be helpful in understanding the "magic" of electricity.

Richard Feynman Electricity - YouTube (http://www.youtube.com/watch?v=kS25vitrZ6g&feature=related)

[Kristi Silber]

Thanks, Jerry. That helps confirm my hypothesis. It's not the actual movement of the electrons that makes electricity move so fast, it's their interaction. Extrapolating from Feynmann's explanation, the repellent forces between the electrons as they are pushed together creates potential energy, resulting in the electromotive force manifested in the electromagnetic field.

[Jerry Peck]

That helps confirm my hypothesis. It's not the actual movement of the electrons that makes electricity move so fast, it's their interaction.

To re-word that, and be consistent with Feynmann's explanation, it's the movement of the electrons (the "free", "excess", or "unbalanced" electrons in excess of the positive protons) which exerts the force on the adjacent electrons (the "free", "excess", or "unbalanced" electrons in excess of the positive protons). I.e., think of it as having several straight magnets laid out end-to-end-to-end, etc., with the like poles facing each other but just far enough away as to not be able to move the next closest magnet.

Now give the end magnetic a quick push toward the closest magnet and that magnet will in turn be forced away from the magnet you pushed and it will push into the next magnet, etc., down the line until all magnets have moved and re-balanced their distance from each other.


Extrapolating from Feynmann's explanation, the repellent forces between the electrons as they are pushed together creates potential energy, resulting in the electromotive force manifested in the electromagnetic field.

Correct.

Have you reviewed his comments on how magnets work (he is asked why like poles repel each other Richard Feynman Magnets - YouTube (http://www.youtube.com/watch?v=MO0r930Sn_8&feature=relmfu) ) and his comments on other things? Quite interesting. He "explains" such things are how a mirror works ( Richard Feynman Mirror - YouTube (http://www.youtube.com/watch?v=6tuxLY94LXw&feature=relmfu) ), why trains stay on their tracks ( What keeps a train on the track? - YouTube (http://www.youtube.com/watch?v=WAwDvbIfkos&feature=related) ), and all kinds of other things. I've watched a number of his explanations, but not all of them, but all the ones I've watched are interesting and make you think (which is why he makes them ... to make you think).

[Kristi Silber]

It may be a little ambiguous, but the way I worded it isn't incorrect or inconsistent with Feynman. The interaction of the electrons moves much more rapidly than the electrons themselves.

It's not that there's a big excess of electrons within a wire, they are just getting bumped from atom to atom because the repellent force is greater than the force holding the electrons to the protons. It's a property of metals that the electrons are loosely bound to the protons.

I watched the one on God yesterday, and the one on magnets just now. Physicists have always kind of amazed me. They see the world differently than others. Feynman is awesome.

[Jerry Peck]

The interaction of the electrons moves much more rapidly than the electrons themselves.

The problem with that wording is that the next interaction can only happen *after* the next electron moves, and it is that movement which causes the force to move the next electron.


Feynman is awesome.

Absolutely! I figured you would like him because of your scientific inclination.

He's the guy NASA called to investigate why the shuttle Columbia exploded shortly after lift off (okay, he was not 'the only guy' investigating it, but I believe he was the lead guy they called to head it up).

There are other interesting things out there by something called Sixty Symbols or something like that. They explains lot of stuff too.

Bouncing Balls - Sixty Symbols - YouTube (http://www.youtube.com/watch?v=SRGf0Mq2Zwg&feature=relmfu)

Electrons (extra footage uncut) - YouTube (http://www.youtube.com/watch?v=0Ffs2MvIA8w&feature=related)

Work - Sixty Symbols - YouTube (http://www.youtube.com/watch?v=A25LHlMK_v8)

[Kristi Silber]

...the next interaction can only happen *after* the next electron moves, and it is that movement which causes the force to move the next electron.



Are you picturing it like one is displaced from an atom, and when it's gone the next fills its spot? It's much more fluid than that. Electrons are constantly in motion even without current influencing them.

Think of a bunch of dominoes lined up, 2 meters long. You push them over, and they take 10 seconds for them all to fall. The force has traveled 2 meters in 10 seconds. Each domino has moved 2 centimeters in ten seconds. The energy in this case traveled 100 times the speed of the domino.

The interaction of the dominoes has traveled much faster than the dominoes themselves.

[Jerry Peck]

The interaction of the dominoes has traveled much faster than the dominoes themselves.

However, like what I said about the electrons - the dominoes had to move, each single one by each next one, for that to happen.

An easy way to demonstrate that is to set your dominoes up in a curve ... and get the curve wrong ... you push the first domino and it falls against the next domino which falls against the next which ... until one of the falling dominoes misses the one it was supposed to fall on.

It takes the dominoes *moving* (falling, or flowing in the case of electrons) to cause what you describe, and its takes the electrons "flowing" to cause the interaction and force upon the next electron.

Yes, electrons are always "moving" about the nucleus of the atom, but that is like a tethered ball - it still stays with its own atom, for current to flow, the tether needs to be cut ... that now-free-electron can do some serious business.

Like the man said (I believe I included that link) ... its difficult to describe the electron as a particle without describing it as a wave, and to describe it as a wave is not easy when including its actions as a particle, the two descriptions do not always mesh.

Beyond that, it is beyond me, once he started talking about describing the particle as a wave so it could be described mathematically, and he said he was not a good mathematician ... I'm not as good as he is - he is in the pro's ball park hitting home runs and I'm in the sandlot bunting the ball around. trying to get a walk so I can get on base. :D

[Kristi Silber]

I guess we aren't communicating well. We seem to be agreeing about the fundamentals, and I don't understand why you think what I said ("It's not the actual movement of the electrons that makes electricity move so fast, it's their interaction.") is inconsistent. I'm addressing the question of why the velocity of electricity along a wire (nearly the velocity of light) is so much more rapid than the velocity of the electrons along it. I'm not arguing that the electrons don't move, I'm saying that the repellent force travelling ahead of their movement is what determines the velocity of electricity. Move one electron slightly, and almost instantaneously millions of other electrons down the line are also moved slightly as a result.

The tether analogy makes it sound like electrons won't be affected by a force until the tether is cut, and after that they respond only to the forces of other electrons. But the orbit of an electron is influenced not only by its associated proton, but also by the forces around it: other electrons (and protons). A better analogy is having a weak positive magnet (proton, we'll call it "P") holding a negative magnet "A" (electron) in random orbit around it (these imaginary magnets don't have poles). Bring another negative magnet, "B", near by, and the first one will be repelled in the opposite direction so that its orbit will shift, and part of its orbit will be more distant from P, where the attractive forces between the A and P are lower. Bring B closer still, and the repellent force will overcome the attraction of P, and A will slip out of orbit. Meanwhile, the change in A's orbit will already have started to influence the orbit of next pair of proton and electron through repellent force, and so on down the line. When A slips out of orbit it repels its neighboring electron out of its orbit, and takes its place.

All this happens so rapidly it's as if the electrons were actually free-flowing, but without the interaction among subatomic particles there would be no potential energy carried through the wire.



Yes, electrons are always "moving" about the nucleus of the atom, but that is like a tethered ball - it still stays with its own atom, for current to flow, the tether needs to be cut ... that now-free-electron can do some serious business.



How do you envision a free electron "doing business"? What would it do? If it were just a bunch of free electrons moving along, they would maintain an even average distance from each other, no potential electrical energy would be involved, and no electromagnetic waves created.

This nice little interactive animation (http://www.colorado.edu/physics/2000/waves_particles/wavpart2.html)shows the strength and direction of the force exerted by the proton on an electron in orbit. It takes some experimentation, but you can get one or more electrons to orbit the proton. There are other nice demonstrations on the site.

(This is a nice discussion! I'm learning as we're going along. I like that.)

[Jerry Peck]

Kristi,

This is what I keep going back to, unless this is no longer a valid post of yours:

So you turn on the electricity at one end of a wire, and it takes time for the electrons to transmit the energy along the wire - thus there is movement of energy, even if there's no net movement of each electron.

There IS a net movement of each electron (not each and every single electron, but, as described in those links, the "free" electrons). It is that movement of each of those electrons which creates the force for the electrical current flow.


The tether analogy makes it sound like electrons won't be affected by a force until the tether is cut, ...

The force that is affecting the electron on the tether is the centrifugal force that is keeping the electron circulating around at the end of the tether. The electron is circulating around the atom in a constrained motion, in one hand it is drawn toward the positive charge proton and its mass, weight, and velocity is offsetting that force, keeping the electron captive on the end of the tether - cut the tether and the electron is free to go, change the force trying to keep the electron toward the proton and the electron will either be attracted to the proton or the electron will be free to go.

I'm re-learning some things I knew many years ago when I was more into electronics, etc., than into electrical (there is a difference), and learning new things due to new concepts and technology (when I was calibrating oscilloscopes at a defense plant most were tube-type, I got to work on some of the first transistor-type oscilloscopes - much more reliable than the tube-type and need much less re-calibration (would hold their calibration longer). One of my supervisors had worked on the team at Bell Labs which invented the transistor.

This is like trying to teach an old dog new tricks, and the old dog hangs with you for a while ... then goes and lays down on the porch in the shade ... I'm going to go lay down in the shade on the porch and let the youngon work on this new trick herself. :)

[bob smit]

Being a Physicist want2b, I've continued to study long after the physic classes that I've long forgotten from my college days.
I strongly suggest reading Leonard Susskind's book 'The Cosmic Landscape' to bring one up to date (if you can ignore his lack of religious convictions, I can).

Leonard is able to communicate incredibly difficult concepts in layman's terms.
The book has the first chapter dedicated to Feynman, 'The world according to Feynman'. Of particular interest to myself is the Feynman diagram pg# 39, that illustrates on a graph, the 3 dimensions of space, time, and an event and how a positron (anti-proton) and an anti-neutron go back in time, thus explaining how/why they disappear.
I would suggest first visiting pg 181. Pg 181 helps to set ones mind in the right gear, as it were. This page includes the reaction via a W-boson to emit a neutrino!

Have I pricked your curiosity? Buy this book. You can thank me later;)

[Kristi Silber]

Thanks for the recommendation, Bob. Sounds interesting. I'll have to put that on my reading list.

I'm also glad that you posted just because I've been meaning to reply to Jerry's post for ages. I started a reply then lost it somehow, and never tackled it again.

Jerry (and others), it's been a great discussion. We're getting into quantum mechanics here, pretty heady stuff by any standard. Not having thought about this in decades, it's not surprising that we sort of ran into an intellectual wall.

One thing I wanted to emphasize to any future reader of this thread is that a lot of the posts here are misinformed, mine among them. We may sometimes sound like we know what we're talking about (or maybe not!), but we're just puzzling things out. And we're definitely oversimplifying - talking about a single proton-electron pair in a copper atom, for instance, which is of course absurd.

I can't let this centrifugal force thing slide. For one thing, there is no such force as people usually envision it - like a ball on a tether. That's inertia, the tendency of an object to continue in its current direction and velocity.

An electron is like a photon, it is a particle and a wave, always moving in sort of a shell around the nucleus, kept in place by the positive charge of the proton. You can't cut that force off like you would a tether, the proton is always going to exert that force, so something else has to come along and act on the electron - another charge, heat, something - if it's going to leave the proton. (The electron actually has multiple distances it can be from the proton, different orbits associated with different energy levels. Excite the atom, and the electron gets further from the proton, then as it falls back into its original orbit it releases light.)

It's been a fun discussion!

[bob smit]

I hear that Kristy!
Yes, it is actually centripetal force.
Wish you hadn't mentioned the various energy levels of an electron...
I've been wrestling with the question as to why there are distinct energy levels with no in between. Futile I know, as the best minds of our day are still wrestling with the question.
Perhaps I'll come up with the answer in my sleep as it seems to work better than the pea brain that accompanies me whilst awake:cool:

[Kristi Silber]

Right - in the tethered ball analogy, the centripetal force acts perpendicularly to the direction of the ball, with its vector toward the center post. And even when the opposite charges of the electron and proton cause the attraction, so there's force going both directions, the mass of the proton is so much greater than that of the electron that I suppose the force exerted by the electron can be ignored.

I read yesterday that the different orbits are not quite as neat and discrete as people are usually taught, though it's still helpful to think of them that way. Still, I know what you mean. Maybe I'll look into that when I have a bit of time. You've got me curious now. It's something about "packets" of energy and the wave/particle duality, I think.

[bob smit]

Yep, It's called 'quantum jitters', like just before I do a homeowner dyi new home inspection:eek: