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#1
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Alternating Current means ALTERNATING current?
I was talking to an electrician doing some work in my building and
started asking some questions about AC. My electrical knowledge is quite limited, but in the course of the conversation, I said something about the the flow of current reversing direction twice every 60th of a second. He said "No, the ACTUAL current always flows in one direction from the hot to the neutral and it's the AMOUNT of current flowing that alternates." Isn't that the definition of modulated DC, not AC? I couldn't make any sense of his explanation of what he meant by "actual current", but he insisted that current flows in ONE DIRECTION ONLY. I really don't get what he's talking about - but he's the professional. Can someone fill me in? |
#3
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Ben Bradley wrote in message . ..
On 16 Jun 2004 15:01:18 -0700, (apa) wrote: I was talking to an electrician doing some work in my building and started asking some questions about AC. My electrical knowledge is quite limited, but in the course of the conversation, I said something about the the flow of current reversing direction twice every 60th of a second. He said "No, the ACTUAL current always flows in one direction from the hot to the neutral and it's the AMOUNT of current flowing that alternates." Isn't that the definition of modulated DC, not AC? I couldn't make any sense of his explanation of what he meant by "actual current", but he insisted that current flows in ONE DIRECTION ONLY. I really don't get what he's talking about - but he's the professional. Can someone fill me in? I'm trying to interpret that in a way that he's right, but I can't. You could almost say "power comes out of the hot" but you could just as well say it comes out of the neutral - you need both connected to get power. The "hot" is called the hot because it's the one that has the high voltage relative to ground - the neutral has (almost) no voltage compared to ground (because it's acutually connected to ground at the fuse/breaker box). But during 1/120th second (in the USA and other places where 60Hz power is used), current (presuming a resisiive load such as a light bulb) comes out of the hot and goes into the neutral, and during the next 120th second current goes into the hot and comes out of the neutral. ----- http://mindspring.com/~benbradley That exactly what I thought. I would have disregarded what he said if he wasn't an electrician. Thanks for the confirmation. |
#4
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apa wrote:
I was talking to an electrician doing some work in my building and started asking some questions about AC. My electrical knowledge is quite limited, but in the course of the conversation, I said something about the the flow of current reversing direction twice every 60th of a second. He said "No, the ACTUAL current always flows in one direction from the hot to the neutral and it's the AMOUNT of current flowing that alternates." Isn't that the definition of modulated DC, not AC? I couldn't make any sense of his explanation of what he meant by "actual current", but he insisted that current flows in ONE DIRECTION ONLY. I really don't get what he's talking about - but he's the professional. Can someone fill me in? For all I know you are the professional here. My regards Bert Kraaijpoel |
#5
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AC = Turn the knob and stand in front to feel the cold air.
This definition is the only one you need from June through September :-) apa wrote: I was talking to an electrician doing some work in my building and started asking some questions about AC. My electrical knowledge is quite limited, but in the course of the conversation, I said something about the the flow of current reversing direction twice every 60th of a second. He said "No, the ACTUAL current always flows in one direction from the hot to the neutral and it's the AMOUNT of current flowing that alternates." Isn't that the definition of modulated DC, not AC? I couldn't make any sense of his explanation of what he meant by "actual current", but he insisted that current flows in ONE DIRECTION ONLY. I really don't get what he's talking about - but he's the professional. Can someone fill me in? |
#6
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Umm... Well, if you equate current to electrons, neither of you is "right."
If you measure peak voltage, than he's right in one regard, the voltage does fluctuate. The electrons don't get a chance to go anywhere, really, as the polarity of the electric field keeps reversing. Think of it this way: even the ground has electrons. The electric field of the neutral (theoretically) is the same as the ground, leading to no electric potential between the two (ground does have a charge, but everything is relative to it). Hot, however, has a potential relative to ground of 120v RMS (US). This is, in one cycle the field goes 0 to (-)120 (can't remember the actual peak voltage) to 0 to (+)120 to 0. When the cycle is negative, electrons move a short distance from the hot wire to the neutral. When it is positive, it attracts electrons from the neutral to the hot. Now, on a good day it is safe to handle a live neutral, but I've read 80v from a neutral before, and almost always get zapped. Oh, the above holds true to single phase only. Dual phase is a little more complicated because it involves the interaction of two fields relative to each other... And I don't trust electricians; been in too many situations where I've been shocked by shabby work and end up fixing it myself. You'd find a physics book more informative than your electrician for sure. -- ____________________________________ Brandon Anderson Lighting, Sound, and Video http://www.bdanderson.com/ "apa" wrote in message om... I was talking to an electrician doing some work in my building and started asking some questions about AC. My electrical knowledge is quite limited, but in the course of the conversation, I said something about the the flow of current reversing direction twice every 60th of a second. He said "No, the ACTUAL current always flows in one direction from the hot to the neutral and it's the AMOUNT of current flowing that alternates." Isn't that the definition of modulated DC, not AC? I couldn't make any sense of his explanation of what he meant by "actual current", but he insisted that current flows in ONE DIRECTION ONLY. I really don't get what he's talking about - but he's the professional. Can someone fill me in? |
#7
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The only thing I'd disagree with is that current flows, yes, but electrons
stay where they are. They excite the next molecule when polarized in one direction by current, but electrons don't move down a line even in DC. Otherwise all the electrons would ultimately go away and you'd no longer have molecules of whatever the carrier is and no current would flow. In other words, an electrical current would be a catalyst that would change the atomic weight of a molecule in DC. In AC the electron simply excites the next molecule's electron in a positive direction, and then a negative direction, doing this 120 times a second in a two phase system, 180 times in a three phase system. I recall Stephen Paul (RIP) having what turned out to be a rather heated discussion here about the fact that electrons don't actually flow, but a lot of people either didn't get the discussion, or have this weird idea that electrons jump from molecule to another in the direction of current. Even if this were true, the best case is that an electron would be shared between two molecules in AC generation. But, in fact, the initially excited electron only jumps to an excited state within it's molecule (more enegetic orbit), which excites the next molecule, and then it drops back to it's "steady" state when power isn't flowing. The only difference is the direction of the phase, meaning current flow. The kicker is in the fact that, at absolute zero you get a halt in brownian movement, and yet you also get absolutely no resistance to current flow, which absolutely means that electrons aren't flowing down a copper wire. For reference of Stephens somewhat rambling post, read http://www.google.com/groups?q=elect...dio.com&rnum=2 -- Roger W. Norman SirMusic Studio "Brandon Anderson" wrote in message ... Umm... Well, if you equate current to electrons, neither of you is "right." If you measure peak voltage, than he's right in one regard, the voltage does fluctuate. The electrons don't get a chance to go anywhere, really, as the polarity of the electric field keeps reversing. Think of it this way: even the ground has electrons. The electric field of the neutral (theoretically) is the same as the ground, leading to no electric potential between the two (ground does have a charge, but everything is relative to it). Hot, however, has a potential relative to ground of 120v RMS (US). This is, in one cycle the field goes 0 to (-)120 (can't remember the actual peak voltage) to 0 to (+)120 to 0. When the cycle is negative, electrons move a short distance from the hot wire to the neutral. When it is positive, it attracts electrons from the neutral to the hot. Now, on a good day it is safe to handle a live neutral, but I've read 80v from a neutral before, and almost always get zapped. Oh, the above holds true to single phase only. Dual phase is a little more complicated because it involves the interaction of two fields relative to each other... And I don't trust electricians; been in too many situations where I've been shocked by shabby work and end up fixing it myself. You'd find a physics book more informative than your electrician for sure. -- ____________________________________ Brandon Anderson Lighting, Sound, and Video http://www.bdanderson.com/ "apa" wrote in message om... I was talking to an electrician doing some work in my building and started asking some questions about AC. My electrical knowledge is quite limited, but in the course of the conversation, I said something about the the flow of current reversing direction twice every 60th of a second. He said "No, the ACTUAL current always flows in one direction from the hot to the neutral and it's the AMOUNT of current flowing that alternates." Isn't that the definition of modulated DC, not AC? I couldn't make any sense of his explanation of what he meant by "actual current", but he insisted that current flows in ONE DIRECTION ONLY. I really don't get what he's talking about - but he's the professional. Can someone fill me in? |
#8
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The kicker is in the fact that, at absolute zero you get a halt in brownian movement, and yet you also get absolutely no resistance to current flow, which absolutely means that electrons aren't flowing down a copper wire. so at absolute zero everything conducts ? even glass and rubber? George |
#9
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Good question, but even if it doesn't, it doesn't mean that electrons flow
down a rubber cable! g -- Roger W. Norman SirMusic Studio "George" wrote in message ... The kicker is in the fact that, at absolute zero you get a halt in brownian movement, and yet you also get absolutely no resistance to current flow, which absolutely means that electrons aren't flowing down a copper wire. so at absolute zero everything conducts ? even glass and rubber? George |
#10
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I had been taught amongst other explainations that it's the
transmission of free holes and not the electron. On Sun, 20 Jun 2004 08:58:07 -0400, "Roger W. Norman" wrote: The only thing I'd disagree with is that current flows, yes, but electrons stay where they are. They excite the next molecule when polarized in one direction by current, but electrons don't move down a line even in DC. Otherwise all the electrons would ultimately go away and you'd no longer have molecules of whatever the carrier is and no current would flow. In other words, an electrical current would be a catalyst that would change the atomic weight of a molecule in DC. In AC the electron simply excites the next molecule's electron in a positive direction, and then a negative direction, doing this 120 times a second in a two phase system, 180 times in a three phase system. I recall Stephen Paul (RIP) having what turned out to be a rather heated discussion here about the fact that electrons don't actually flow, but a lot of people either didn't get the discussion, or have this weird idea that electrons jump from molecule to another in the direction of current. Even if this were true, the best case is that an electron would be shared between two molecules in AC generation. But, in fact, the initially excited electron only jumps to an excited state within it's molecule (more enegetic orbit), which excites the next molecule, and then it drops back to it's "steady" state when power isn't flowing. The only difference is the direction of the phase, meaning current flow. The kicker is in the fact that, at absolute zero you get a halt in brownian movement, and yet you also get absolutely no resistance to current flow, which absolutely means that electrons aren't flowing down a copper wire. For reference of Stephens somewhat rambling post, read http://www.google.com/groups?q=elect...dio.com&rnum=2 |
#11
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"Bryan Beasleigh" wrote ...
I had been taught amongst other explainations that it's the transmission of free holes and not the electron. Anybody who has been on the Los Angeles "free"way system during daylight hours knows exactly what "hole- flow" is. :-) Except that eventually you get to your destination in your electron-vehicle while the copper atoms in the wire stay put and just swap electrons in and out. |
#12
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I take it you didn't read Stephen's explanation, although I have to admit,
you have to read the hole thing, mentally cut about 40% and then glue it all together to see what he's talking about. Unfortunately, such a talented man as Stephen was plagued with an extreme form of arthritus and endured a quite few years of incredible pain along with the incumbent medication. But the sheer genius of the man isn't in question with any of us who knew him and talked to him regularly. When it starts getting into quantum mechanics, I really start having a hard time grasping some of the concepts. Superstring theory has been giving me a headache for about the last 5 years. Electricity seems like it should be so simple, but it still hurts when I grab a hot wire! g -- Roger W. Norman SirMusic Studio "Bryan Beasleigh" wrote in message ... I had been taught amongst other explainations that it's the transmission of free holes and not the electron. On Sun, 20 Jun 2004 08:58:07 -0400, "Roger W. Norman" wrote: The only thing I'd disagree with is that current flows, yes, but electrons stay where they are. They excite the next molecule when polarized in one direction by current, but electrons don't move down a line even in DC. Otherwise all the electrons would ultimately go away and you'd no longer have molecules of whatever the carrier is and no current would flow. In other words, an electrical current would be a catalyst that would change the atomic weight of a molecule in DC. In AC the electron simply excites the next molecule's electron in a positive direction, and then a negative direction, doing this 120 times a second in a two phase system, 180 times in a three phase system. I recall Stephen Paul (RIP) having what turned out to be a rather heated discussion here about the fact that electrons don't actually flow, but a lot of people either didn't get the discussion, or have this weird idea that electrons jump from molecule to another in the direction of current. Even if this were true, the best case is that an electron would be shared between two molecules in AC generation. But, in fact, the initially excited electron only jumps to an excited state within it's molecule (more enegetic orbit), which excites the next molecule, and then it drops back to it's "steady" state when power isn't flowing. The only difference is the direction of the phase, meaning current flow. The kicker is in the fact that, at absolute zero you get a halt in brownian movement, and yet you also get absolutely no resistance to current flow, which absolutely means that electrons aren't flowing down a copper wire. For reference of Stephens somewhat rambling post, read http://www.google.com/groups?q=elect...thor:Step hen +author:Paul&hl=en&lr=&ie=UTF-8&selm=3A282138.8010102%40spaudio.com&rnum=2 |
#13
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"Roger W. Norman" The only thing I'd disagree with is that current flows, yes, but electrons stay where they are. ** There is a slow but definite "electron drift speed" for a current in a wire. Do a search Google on that phrase and see. They excite the next molecule when polarized in one direction by current, but electrons don't move down a line even in DC. ** A DC current of 1 amp in a wire means that that ** 6.2 x 10 exp 18 ** electrons pass by a point in one second. Otherwise all the electrons would ultimately go away and you'd no longer have molecules of whatever the carrier is and no current would flow. ** A current only flows in a *continuous circuit* - hence so do electrons. None are created or destroyed. In other words, an electrical current would be a catalyst that would change the atomic weight of a molecule in DC. ** Childishly stupid. In AC the electron simply excites the next molecule's electron in a positive direction, and then a negative direction, doing this 120 times a second in a two phase system, 180 times in a three phase system. ** There is no change in the frequency in multi phase power systems. The kicker is in the fact that, at absolute zero you get a halt in brownian movement, and yet you also get absolutely no resistance to current flow, which absolutely means that electrons aren't flowing down a copper wire. ** How completely asinine !!! No resistance ( ie superconductivity) means the electrons flow with perfect ease. BTW Copper wire never becomes a superconductor, even at absolute zero. .............. Phil |
#14
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Have you ever looked into surgery?
Perhaps severing the connection of your optic nerve to your a$$hole might cure that sh!tty outlook that you have . There are several theories and all the math works on each one of them, so who really cares. Kill file time On Mon, 21 Jun 2004 13:04:31 +1000, "Phil Allison" wrote: "Roger W. Norman" The only thing I'd disagree with is that current flows, yes, but electrons stay where they are. ** There is a slow but definite "electron drift speed" for a current in a wire. Do a search Google on that phrase and see. They excite the next molecule when polarized in one direction by current, but electrons don't move down a line even in DC. ** A DC current of 1 amp in a wire means that that ** 6.2 x 10 exp 18 ** electrons pass by a point in one second. Otherwise all the electrons would ultimately go away and you'd no longer have molecules of whatever the carrier is and no current would flow. ** A current only flows in a *continuous circuit* - hence so do electrons. None are created or destroyed. In other words, an electrical current would be a catalyst that would change the atomic weight of a molecule in DC. ** Childishly stupid. In AC the electron simply excites the next molecule's electron in a positive direction, and then a negative direction, doing this 120 times a second in a two phase system, 180 times in a three phase system. ** There is no change in the frequency in multi phase power systems. The kicker is in the fact that, at absolute zero you get a halt in brownian movement, and yet you also get absolutely no resistance to current flow, which absolutely means that electrons aren't flowing down a copper wire. ** How completely asinine !!! No resistance ( ie superconductivity) means the electrons flow with perfect ease. BTW Copper wire never becomes a superconductor, even at absolute zero. ............. Phil |
#15
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"Bryan Beasleigh" Have you ever looked into surgery? ** You should look into psychiatry, Bryan - from the prospective consumers point of view. ............ Phil |
#16
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Why are these necessary?
Phil Allison wrote: ** Childishly stupid. ** How completely asinine !!! Wouldn't a simple "it's not like that", "you're mistaken" or something else, work as well? |
#17
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#18
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"S O'Neill" Why are these necessary? Phil Allison wrote: ** Childishly stupid. ** How completely asinine !!! Wouldn't a simple "it's not like that", "you're mistaken" or something else, work as well? ** No. ............... Phil |
#19
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Hey, you can look up the reference, then ask any number of questions around
here and other places about Stephen's qualifications. I was just stating my understanding of his papers. The man's work at Livermore was widely accepted. Besides, before physics could really get down to HOW electricity works, we had electricity. But if we must get into it, think of particle knowledge of other particle's states. When an electron gets excited, it excites other electrons. Why should an actual electron "flow" from one molecule to another? We are only talking about a molecule's state, not physical movement from one to the other. Else, electricity is a catalyst, and I don't recall electricty being a catalyst. Then I'm dumb and I guess I just found an extremely smart man who's view of the world somewhat followed mine. If that makes me assinine, then that's ok. Stephen was a smart man, and if I didn't follow his reasoning correctly, that's my black eye, not his. -- Roger W. Norman SirMusic Studio "Phil Allison" wrote in message ... "Roger W. Norman" The only thing I'd disagree with is that current flows, yes, but electrons stay where they are. ** There is a slow but definite "electron drift speed" for a current in a wire. Do a search Google on that phrase and see. They excite the next molecule when polarized in one direction by current, but electrons don't move down a line even in DC. ** A DC current of 1 amp in a wire means that that ** 6.2 x 10 exp 18 ** electrons pass by a point in one second. Otherwise all the electrons would ultimately go away and you'd no longer have molecules of whatever the carrier is and no current would flow. ** A current only flows in a *continuous circuit* - hence so do electrons. None are created or destroyed. In other words, an electrical current would be a catalyst that would change the atomic weight of a molecule in DC. ** Childishly stupid. In AC the electron simply excites the next molecule's electron in a positive direction, and then a negative direction, doing this 120 times a second in a two phase system, 180 times in a three phase system. ** There is no change in the frequency in multi phase power systems. The kicker is in the fact that, at absolute zero you get a halt in brownian movement, and yet you also get absolutely no resistance to current flow, which absolutely means that electrons aren't flowing down a copper wire. ** How completely asinine !!! No resistance ( ie superconductivity) means the electrons flow with perfect ease. BTW Copper wire never becomes a superconductor, even at absolute zero. ............. Phil |
#20
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Hey, you can look up the reference, then ask any number of questions around
here and other places about Stephen's qualifications. I was just stating my understanding of his papers. The man's work at Livermore was widely accepted. Besides, before physics could really get down to HOW electricity works, we had electricity. But if we must get into it, think of particle knowledge of other particle's states. When an electron gets excited, it excites other electrons. Why should an actual electron "flow" from one molecule to another? We are only talking about a molecule's state, not physical movement from one to the other. Else, electricity is a catalyst, and I don't recall electricty being a catalyst. Then I'm dumb and I guess I just found an extremely smart man who's view of the world somewhat followed mine. If that makes me assinine, then that's ok. Stephen was a smart man, and if I didn't follow his reasoning correctly, that's my black eye, not his. -- Roger W. Norman SirMusic Studio "Phil Allison" wrote in message ... "Roger W. Norman" The only thing I'd disagree with is that current flows, yes, but electrons stay where they are. ** There is a slow but definite "electron drift speed" for a current in a wire. Do a search Google on that phrase and see. They excite the next molecule when polarized in one direction by current, but electrons don't move down a line even in DC. ** A DC current of 1 amp in a wire means that that ** 6.2 x 10 exp 18 ** electrons pass by a point in one second. Otherwise all the electrons would ultimately go away and you'd no longer have molecules of whatever the carrier is and no current would flow. ** A current only flows in a *continuous circuit* - hence so do electrons. None are created or destroyed. In other words, an electrical current would be a catalyst that would change the atomic weight of a molecule in DC. ** Childishly stupid. In AC the electron simply excites the next molecule's electron in a positive direction, and then a negative direction, doing this 120 times a second in a two phase system, 180 times in a three phase system. ** There is no change in the frequency in multi phase power systems. The kicker is in the fact that, at absolute zero you get a halt in brownian movement, and yet you also get absolutely no resistance to current flow, which absolutely means that electrons aren't flowing down a copper wire. ** How completely asinine !!! No resistance ( ie superconductivity) means the electrons flow with perfect ease. BTW Copper wire never becomes a superconductor, even at absolute zero. ............. Phil |
#21
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"apa" wrote in message om.. I was talking to an electrician doing some work in my building and started asking some questions about AC. My electrical knowledge is quite limited, but in the course of the conversation, I said something about the the flow of current reversing direction twice every 60th of a second. He said "No, the ACTUAL current always flows in one direction from the hot to the neutral and it's the AMOUNT of current flowing that alternates." Isn't that the definition of modulated DC, not AC? I couldn't make any sense of his explanation of what he meant by "actual current", but he insisted that current flows in ONE DIRECTION ONLY. I really don't get what he's talking about - but he's the professional. Can someone fill me in? ** He is using "electrician's logic". The "hot" wire is the one with electricity in it because it can give him a shock while the neutral has no electricity in it because it does not. Therefore the electricity flows from the hot to the cold - just like heat does - in only one direction. ............. Phil |
#22
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"Phil Allison" wrote in message
... "apa" wrote in message om.. I was talking to an electrician doing some work in my building and started asking some questions about AC. My electrical knowledge is quite limited, but in the course of the conversation, I said something about the the flow of current reversing direction twice every 60th of a second. He said "No, the ACTUAL current always flows in one direction from the hot to the neutral and it's the AMOUNT of current flowing that alternates." Isn't that the definition of modulated DC, not AC? I couldn't make any sense of his explanation of what he meant by "actual current", but he insisted that current flows in ONE DIRECTION ONLY. I really don't get what he's talking about - but he's the professional. Can someone fill me in? ** He is using "electrician's logic". The "hot" wire is the one with electricity in it because it can give him a shock while the neutral has no electricity in it because it does not. Therefore the electricity flows from the hot to the cold - just like heat does - in only one direction. ............ Phil I have found that Electricians who have gone through the apprentice schools do, as Phil suggests, use a different way of describing the phenomenon of electrical current flow. In several conversations with journeyman electricians I've come to believe that their way of thinking about electrical circuits serves them well for wiring buildings and adhering to electrical codes. But, for those of us who learned our electrical theory from an electonic perspective, its hard to communicate. For instance, I was trying to convince an electrician that from an electrical potential perspective, the neutral and ground were identical, barring a small potential difference brought about by the resistance of the "grounding neutral" wire that connects neutral in the switch box to earth ground. He simply couldn't accept that they were the same in any way, even if the measured potential difference were zero. To him, the neutral and the 'grounding neutral' had different jobs to do and, therefore, were different. For him, one is the white wire and the other is not; ergo, different. The fact that the copper of one was connected to the copper of the other made no difference. There simply is not much room for deductive reasoning about electrical realities in electrician's school, and, I guess, its better that way. Steve King |
#23
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"Steve King" ... "Phil Allison" ** He is using "electrician's logic". The "hot" wire is the one with electricity in it because it can give him a shock while the neutral has no electricity in it because it does not. Therefore the electricity flows from the hot to the cold - just like heat does - in only one direction. ............ Phil I have found that Electricians who have gone through the apprentice schools do, as Phil suggests, use a different way of describing the phenomenon of electrical current flow. In several conversations with journeyman electricians I've come to believe that their way of thinking about electrical circuits serves them well for wiring buildings and adhering to electrical codes. But, for those of us who learned our electrical theory from an electonic perspective, its hard to communicate. For instance, I was trying to convince an electrician that from an electrical potential perspective, the neutral and ground were identical, barring a small potential difference brought about by the resistance of the "grounding neutral" wire that connects neutral in the switch box to earth ground. He simply couldn't accept that they were the same in any way, even if the measured potential difference were zero. To him, the neutral and the 'grounding neutral' had different jobs to do and, therefore, were different. For him, one is the white wire and the other is not; ergo, different. The fact that the copper of one was connected to the copper of the other made no difference. There simply is not much room for deductive reasoning about electrical realities in electrician's school, and, I guess, its better that way. ** I have some sympathy for the electrician's position in this stance - since the neutral conductor is a current carrying wire while the safety earth (supposedly) is not. The independent and non conducting earth wire is able to supply a barrier to electric shock that the neutral is incapable of. When dealing with appliances (of the plug in sort) neutral and active are treated exactly the same for all safety and insulation requirements since it is *so common* for them to become reversed or there to be no continuity to supply neutral. ........... Phil |
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#25
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In article znr1087475157k@trad, Mike Rivers wrote:
In article writes: I have found that Electricians who have gone through the apprentice schools do, as Phil suggests, use a different way of describing the phenomenon of electrical current flow. In several conversations with journeyman electricians I've come to believe that their way of thinking about electrical circuits serves them well for wiring buildings and adhering to electrical codes. But, for those of us who learned our electrical theory from an electonic perspective, its hard to communicate. To an electrician, there's no functional difference between AC and DC, and only specialized electricians today ever deal with DC, at least in the USA. It's all "electricity" and the instantaneous direction of motion of the electrons is of no concern to his job. Unless he works with polyphase circuits and big electric motors. In these cases, knowing something about AC circuit theory can be useful. Most electricians don't really know much about the differences between AC and DC circuits, and rather than talk about load reactances, they use a weird "power factor" fudge number to estimate current lead or lag without having to think about vectors. That's fine for most applications but it can get you into trouble with nonlinear loads like switching supplies. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#26
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How to answer this question, as I work with AC, electricans, and DC circuits
constantly I am trying to figure out how to answer this question the best. First electrons only displace each other and move only a very small distance with some situations being different(vacum tubes and spark gaps). DC the elecrical potential is alwas postive when referenced to negative, which means that electrons are always being pulled from a negative terminal to a positive terminal. In AC electrons are pulled from the neutral and then pushed towards the neutral. As an electrons move through a resistance(or impedence) each point will drop the voltage, when the eventually reach ground there is no more difference in potential. Basic electroncs theory, hope I haven't missed anything. BTW if you are reading voltage on a neutral(I saw someone mention this someplace) It means that someone has screwed up in a circuit someplace. Rule of thumb with AC is to carry one of those glow sticks I call em that light up when you wave it close to a wire containing AC voltage. I have seen a situation when a contractor had crossed a hot and neutral in the field, which game me 277(1 phase of 480 US) on the neutral referenced to ground. Okay long post, later all. "apa" wrote in message om... I was talking to an electrician doing some work in my building and started asking some questions about AC. My electrical knowledge is quite limited, but in the course of the conversation, I said something about the the flow of current reversing direction twice every 60th of a second. He said "No, the ACTUAL current always flows in one direction from the hot to the neutral and it's the AMOUNT of current flowing that alternates." Isn't that the definition of modulated DC, not AC? I couldn't make any sense of his explanation of what he meant by "actual current", but he insisted that current flows in ONE DIRECTION ONLY. I really don't get what he's talking about - but he's the professional. Can someone fill me in? --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.703 / Virus Database: 459 - Release Date: 6/13/2004 |
#27
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Well, I have some old Romex and it has measurable 120 v AC on the metal
sheathing. Does that count? g I have to fix that one of these days, but it's a 74 year old circuit and I really haven't seen much in terms of problems unless you touch the ceiling fan light chain and the refrigerator at the same time. Or the screws on the light switch box in the bathroom. Ouch! But I'm lazy and I know where the problem is. I just haven't fixed it yet. Most people aren't walking around my house with no shoes and socks and going into the bathroom, nor turning my fan lights on and off. Great as a replacement for caffeine, though. -- Roger W. Norman SirMusic Studio "Chris Warner" wrote in message news:ih9Ac.1679$u%3.337@fed1read04... How to answer this question, as I work with AC, electricans, and DC circuits constantly I am trying to figure out how to answer this question the best. First electrons only displace each other and move only a very small distance with some situations being different(vacum tubes and spark gaps). DC the elecrical potential is alwas postive when referenced to negative, which means that electrons are always being pulled from a negative terminal to a positive terminal. In AC electrons are pulled from the neutral and then pushed towards the neutral. As an electrons move through a resistance(or impedence) each point will drop the voltage, when the eventually reach ground there is no more difference in potential. Basic electroncs theory, hope I haven't missed anything. BTW if you are reading voltage on a neutral(I saw someone mention this someplace) It means that someone has screwed up in a circuit someplace. Rule of thumb with AC is to carry one of those glow sticks I call em that light up when you wave it close to a wire containing AC voltage. I have seen a situation when a contractor had crossed a hot and neutral in the field, which game me 277(1 phase of 480 US) on the neutral referenced to ground. Okay long post, later all. "apa" wrote in message om... I was talking to an electrician doing some work in my building and started asking some questions about AC. My electrical knowledge is quite limited, but in the course of the conversation, I said something about the the flow of current reversing direction twice every 60th of a second. He said "No, the ACTUAL current always flows in one direction from the hot to the neutral and it's the AMOUNT of current flowing that alternates." Isn't that the definition of modulated DC, not AC? I couldn't make any sense of his explanation of what he meant by "actual current", but he insisted that current flows in ONE DIRECTION ONLY. I really don't get what he's talking about - but he's the professional. Can someone fill me in? --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.703 / Virus Database: 459 - Release Date: 6/13/2004 |
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On 16 Jun 2004 15:01:18 -0700, (apa) wrote:
I was talking to an electrician doing some work in my building and started asking some questions about AC. My electrical knowledge is quite limited, but in the course of the conversation, I said something about the the flow of current reversing direction twice every 60th of a second. He said "No, the ACTUAL current always flows in one direction from the hot to the neutral and it's the AMOUNT of current flowing that alternates." Isn't that the definition of modulated DC, not AC? I couldn't make any sense of his explanation of what he meant by "actual current", but he insisted that current flows in ONE DIRECTION ONLY. I really don't get what he's talking about - but he's the professional. Can someone fill me in? He is a professional electrician. That means you have a slight chance he won't blow your house up with his work. But he isn't a physicist. You are right - he is wrong. d Pearce Consulting http://www.pearce.uk.com |
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