Fuse and Cable Directionality

[DonH50]

Actually, audio fuses are only used in AC audio circuits, but I suppose there could be a situation when a fuse is used in a DC circuit. Refer to the fuse datasheets (Exhibit A) from my post yesterday - the measured differences in resistivity of a number of audiophile and non-audiophile fuses were performed for fuses in AC circuits.

The measured difference is tiny and somewhat random as one would expect making milliohm resistance measurements. It will be swamped by differences in connectors and cables to the speakers. In general to reduce voltage (IR, current times resistance) drop you'd want the largest conductor, thus largest fuse, possible that does not exceed the recommended current rating.

The HiFi Tuning paper shows mostly DC measurements plus some LF (e.g. wall power) and (vector) impedance AC measurements. They mention leaded fuses are better, which makes me wonder about the influence of the fuse holder(s) on the measurements. Since they are a German company, is it correct that say 44,47 millohms in their table is the same as 44.47 milliohms (USA decimal point) or 0.04447 ohms? They state they measured slow-blow fuses, which are manufactured at least a couple of different ways, thus will have significantly different resistance depending upon construction. Still small, but different. The measurement will also change over time, current flow, and environmental conditions (mainly temperature).

It would be interesting to see how the resistance changed before and after cryo treatment.

Normally low-resistance measurements require a four-wire (Kelvin) measurement for accuracy. Otherwise, the contact and probe lead resistance will introduce errors. That is usually a DC measurement though can be extended to AC as well. Vector impedance is tricky with very low impedances; my world is not low-frequency, but for relative broadband power planes (DC to >1 GHz) I use a four-port VNA (vector network analyzer) configured similar to the standard four-point DC setup to measure very low impedances (down to 1 milliohm or below), and a special test circuit to provide force and sense connectors for the VNA. The resulting S-parameter measurements can be converted to whatever format and units are appropriate for the application (often impedance in ohms magnitude and degrees).

You could also measure the drop using a sensitive voltmeter with high-impedance input, though the value will depend upon the current through the fuse, and the fuse must be in steady-state for accurate low-level readings. Not only constant (if AC, rms) current but temperature (and implicitly any airflow) must be tightly controlled. Whenever I have done those sort of measurements the device under test (DUT, fuse or whatever) was mounted in a sealed chamber with tight environmental control and allowed to reach steady-state before taking measurements. Then a number of measurements were taken over a period of time (minutes to hours or months depending upon the device and test specifications) to check variance.

When the “signal” in either + or - wire moves in the direction of the speaker it causes the diaphragm to move. But when the “signal“ moves away from the speaker on either wire it does nothing. For a fuse, the signal moves in both directions on the wire it’s attached to according to the instantaneous audio frequency. It’s easy to see that the best fuse direction is when the voltage drop is lowest in the direction of the speakers.

AC means "alternating current"; the current alternates from positive to negative relative to the reference (typically 0 A). In one direction the diaphragm will move out; in the other, the diaphragm will move in. The only time it does "nothing" is when the current is zero.

 

[Geoffkait]

The measured difference is tiny and somewhat random as one would expect making milliohm resistance measurements. It will be swamped by differences in connectors and cables to the speakers. In general to reduce voltage (IR, current times resistance) drop you'd want the largest conductor, thus largest fuse, possible that does not exceed the recommended current rating.

The HiFi Tuning paper shows mostly DC measurements plus some LF (e.g. wall power) and (vector) impedance AC measurements. They mention leaded fuses are better, which makes me wonder about the influence of the fuse holder(s) on the measurements. Since they are a German company, is it correct that say 44,47 millohms in their table is the same as 44.47 milliohms (USA decimal point) or 0.04447 ohms? They state they measured slow-blow fuses, which are manufactured at least a couple of different ways, thus will have significantly different resistance depending upon construction. Still small, but different. The measurement will also change over time, current flow, and environmental conditions (mainly temperature).

It would be interesting to see how the resistance changed before and after cryo treatment.

Normally low-resistance measurements require a four-wire (Kelvin) measurement for accuracy. Otherwise, the contact and probe lead resistance will introduce errors. That is usually a DC measurement though can be extended to AC as well. Vector impedance is tricky with very low impedances; my world is not low-frequency, but for relative broadband power planes (DC to >1 GHz) I use a four-port VNA (vector network analyzer) configured similar to the standard four-point DC setup to measure very low impedances (down to 1 milliohm or below), and a special test circuit to provide force and sense connectors for the VNA. The resulting S-parameter measurements can be converted to whatever format and units are appropriate for the application (often impedance in ohms magnitude and degrees).

You could also measure the drop using a sensitive voltmeter with high-impedance input, though the value will depend upon the current through the fuse, and the fuse must be in steady-state for accurate low-level readings. Not only constant (if AC, rms) current but temperature (and implicitly any airflow) must be tightly controlled. Whenever I have done those sort of measurements the device under test (DUT, fuse or whatever) was mounted in a sealed chamber with tight environmental control and allowed to reach steady-state before taking measurements. Then a number of measurements were taken over a period of time (minutes to hours or months depending upon the device and test specifications) to check variance.


AC means "alternating current"; the current alternates from positive to negative relative to the reference (typically 0 A). In one direction the diaphragm will move out; in the other, the diaphragm will move in. The only time it does "nothing" is when the current is zero.

Sorry but there is nothing random about the measurements. At the risk of repeating myself the best-sounding direction for all fuses is when the lowest voltage drop is measured across the fuse in the direction of the speakers.

I didn’t say the difference wasn’t tiny, but there is a difference. Ie., the fuse wire is not symmetrical. It’s not symmetrical physically or electrically. I also am NOT saying the small difference in resistivity is responsible for the differences in sound when both directions are evaluated by listening tests, which is exactly what is stated in the data sheets.

Thanks for defining what AC is, but in reality current doesn’t change directions, only the electrons change directions. Current is a scalar quantity thus has no direction. It’s a calculated number, it’s calculated from the number of electrons (charge carriers) moving through a given wire cross-section.

 

[Atmasphere]

Actually, audio fuses are only used in AC audio circuits, but I suppose there could be a situation when a fuse is used in a DC circuit. Refer to the fuse datasheets (Exhibit A) from my post yesterday - the measured differences in resistivity of a number of audiophile and non-audiophile fuses were performed for fuses in AC circuits.

When the “signal” in either + or - wire moves in the direction of the speaker it causes the diaphragm to move. But when the “signal“ moves away from the speaker on either wire it does nothing. For a fuse, the signal moves in both directions on the wire it’s attached to according to the instantaneous audio frequency. It’s easy to see that the best fuse direction is when the voltage drop is lowest in the direction of the speakers.

Fuses get used in DC circuits all the time... The second paragraph here is outright false (as is the first...). These statements suggest the writer has no exposure to the way electronics actually work.

Fuses, unlike fuse holders, are *predictable* in the sense the correct direction of a fuse never changes, the fuse is physically and electrically *asymmetrical.* Once the correct direction of a fuse is established it’s effect on sound is *repeatable* and *transferrable* to other systems. Furthermore, if *both* fuse end caps and *both* ends of the fuse holder are deformed as you claim they wouldn’t be directional, anyway, they’d be symmetrical.

Furthermore, the measurements of fuse resistivity in both directions provided in Exhibit A I posted earlier in the day were made without fuse holders. In any case, the audible effects, if any, of any fuse holder imperfections would certainly be much less profound and entirely different from that of fuse directionality. if both end caps suffered the same deformation you claim there would be no directionality issue. If the fuse cannot make positive physical or electrical contact with a particular fuse holder adjust the fuse holder or replace it pronto.

The term directionality refers to fuses and wire and *unshielded* cable - shielding is a separate, though similar, issue.

Fuses if directional would heat up and fail? You’re kidding, right?

Not kidding. A directionality indicates a diode and therefore Voltage drop in one direction of the AC only. The heat from the primative diode would thus blow the fuse. Such diodes do not exist in the fuse though, which is why they don't do that.

The above statements in the quote are all nonsense. If they were true, the fuse industry would look very different today! Bussman and Littlefuse, the makers of the best fuses available to high end audio, would be out of a job.

Sorry but there is nothing random about the measurements.
Thanks for defining what AC is, but in reality current doesn’t change directions, only the electrons change directions. Current is a scalar quantity thus has no direction, it’s calculated from the number of electrons (charge carriers) moving through a given wire cross-section. The diaphragm action I just explained a little while ago.

Yikes! Again all nonsense as any engineer can tell anyone brave enough (unless you really don't mind getting laughed at) to ask if this statement is true. The fallacy, for anyone interested, is electron flow is current flow plain and simple. So when electrons reverse direction, so does current.

Yet, no one has ever heard of any equipment damage or fire or whatever due to an audiophile fuse - even though more than 120,000 fuses have been sold by the top 3 boutique fuse (as you say) companies in recent years. Faint heart ne’er won fair maiden.

This statement is false. Some of the boutique fuses do not blow at their ratings. We've seen this when customers have used them in our gear. Another example, one fuse in particular employs Teflon tubing to damp the motion of the fuse element (fast blow fuses change their length due to heating; you can see them move, for example when the amp or what ever is powered up). When the fuse blows, the liquid metal is held inside the tubing in a plasma state and continues to conduct. Rodger Modjesky documented this phenomena (on audiogon IIRC) when a customer's amp came in with a damaged power transformer on this account.

I really thought that the fact that this thread started on April 1st that I'd see some pretty funny stuff. An ironically funny part added to it that at least one person active on this thread seems to think its real Again, you can demonstrate everything I wrote in my first post with a simple DVM. Not rocket science or 'quantum'; just Ohm's Law.

Occam's Razor is a method of helping to winnow out the truth. Essentially it states that given explanations for a thing (such as fuse directionality) the simpler explanation is probably the correct one. So we've seen the rather complex explanations offered by Geoff, or it could simply be Ohm's Law (a 4th grade level formula).

 

[Geoffkait]

People would generally be much better off if they believed in too much rather than too little. Grasping at straws much?

I didn’t say fuses couldn‘t be used in DC circuits, in fact I said they could be used in DC circuits. Nice logical fallacy. The fuse data sheets which I assume you haven’t read states that fuse directionality applies to both DC and AC circuits.

Winnow out the truth? That’s gold, Jerry, gold!

I challenge you to prove that fuses are not directional.

 

[racerxnet]

Funny how some people think a fuse is a 1 way gate with a leak. The generation of AC swings both ways during rotor rotation from North to South.

 

[Atmasphere]

People would generally be much better off if they believed in too much rather than too little. Grasping at straws much?

I didn’t say fuses couldn‘t be used in DC circuits, in fact I said they could be used in DC circuits. Nice logical fallacy. The fuse data sheets which I assume you haven’t read states that fuse directionality applies to both DC and AC circuits.

Winnow out the truth? That’s gold, Jerry, gold!

Yes, it is.
Above you're committing a Strawman Fallacy; here is what you said:

Actually, audio fuses are only used in AC audio circuits

Thus your comment is inherently false.

This sort of distortion isn't getting you anywhere. I've read plenty of fuse specs and no-one but the 'boutique' stuff mentions anything about directionality because it does not exist. You have no proof or even evidence it does, period, full stop.

 

[Geoffkait]

What I actually wrote is,

“Actually, audio fuses are only used in AC audio circuits, but I suppose there could be a situation when a fuse is used in a DC circuit.”

Nice try. I’m still waiting for you to “winnow out the truth.“

 

[Atmasphere]

Yes- with your feet to the fire, we see how you attempted to distort your own words.

The truth, which is obvious, is that fuse directionality does not exist. That is what I'm up to, nothing else. Drop the innuendo.

Anyone can demonstrate easily the truth of my first post with a DVM.

 

[Geoffkait]

Is it true that when you lie your pants really are on fire? One assumes you‘ve given up pushing your bogus fuse holder hypothesis. Good move.

 

[Geoffkait]

Funny how some people think a fuse is a 1 way gate with a leak. The generation of AC swings both ways during rotor rotation from North to South.

Logical fallacy alert! E for effort.

 

[DonH50]

Sorry but there is nothing random about the measurements. At the risk of repeating myself the best-sounding direction for all fuses is when the lowest voltage drop is measured across the fuse in the direction of the speakers.

There is a random element in any measurement. Nothing is perfect, including a measurement system. It has finite resolution, dynamic range, accuracy, and precision, plus there will be run-to-run variances that should be assessed through multiple trials and such. IIRC the absolute accuracy and noise floor of the measurement devices was not stated in the article but I did not look all that closely. Measuring very low resistance is hard and run-to-run variations tend to be pretty high due to contact resistance, changing environmental and test conditions (e.g. temperature, supply drift, etc.), and so forth.

I didn’t say the difference wasn’t tiny, but there is a difference. Ie., the fuse wire is not symmetrical. It’s not symmetrical physically or electrically. I also am NOT saying the small difference in resistivity is responsible for the differences in sound when both directions are evaluated by listening tests, which is exactly what is stated in the data sheets.

Were the listening tests double blind? It also matters where in the system the fuses are inserted; you are implying they are all in the AC signal path, but other threads on fuses discuss their use in the power supply from wall inlet fuses to DC rail fuses. The sub-milliohm changes would be swamped by things like swapping cables or just inserting the fuses multiple times. The range of average resistance readings, assuming that's what they are, do indeed indicate a difference in the magnitude of resistance (and thus voltage drop) for different fuses, but the directionality part is what seems suspect for a passive series component at audio frequencies. That part of the claim implies some sort of materials shift or rectification, which again points to differences in connections to and through the fuse, but the directional aspect claimed is fractions of a milliohm, which could be within measurement error.

The modulation of fuse resistance with varying current (and temperature) is well-known and is one reason things like power amps either eschew fuses in the signal path or place them within the feedback loop so any change is compensated. Your application is then only fuses in speakers or speaker cables? Most speakers I have seen only fuse the mid/tweeter sections if anything (lower power and thus lower current), and many speakers do not include fuses at all.

Thanks for defining what AC is, but in reality current doesn’t change directions, only the electrons change directions. Current is a scalar quantity thus has no direction. It’s a calculated number, it’s calculated from the number of electrons (charge carriers) moving through a given wire cross-section.

Current is not a pure scalar, i.e. magnitude only, except for an ideal (pure) DC current (with no noise, which is impossible except theoretically). Current flow is not constant and is phased with respect to voltage since voltage fields move the carriers (some use electrons, some use holes, in defining current flow, but the net result is the same). If voltage reverses polarity, current flow follows as driven by the voltage field, and that is back to why the term AC is used. The magnitude can be traced back to carriers, but there is also timing involved, which results in a vector quantity (magnitude and phase).

I am confused that, if current is caused by moving electrons (actually charge, in coulombs/second), and electrons change direction, how does current not change direction? If I measure current through an AC line, it clearly changes direction, and I am normally measuring at the macro (not electron) level. That is with respect to some reference, typically 0 V, of course. At the quantum level, electron flow (and thus current) driven by voltage fields does change direction with voltage polarity, by any reference I could find from basic Ohm's Law to my quantum mechanics grad texts. I suppose you can debate drift velocity vs. charge velocity and so forth but we're already far beyond what most forum members are likely to follow, or care about.

I do not see any hope of changing anyone's mind, though finding the actual reason behind audible differences when changing fuse orientation would be interesting. It would require further audio (listening) testing unlikely to be performed, however, to rule out perceptual bias.

 

[Atmasphere]

I do not see any hope of changing anyone's mind, though finding the actual reason behind audible differences when changing fuse orientation would be interesting. It would require further audio (listening) testing unlikely to be performed, however, to rule out perceptual bias.

I described the why of it in my first post. And why you don't need to reverse the fuse to get exactly the same results.

 

[DonH50]

I described the why of it in my first post. And why you don't need to reverse the fuse to get exactly the same results.

Sorry, missed it among the chaff. But I was really going down the "proof of listening" DBT path that is so maligned.

 

[Alrainbow]

Has anyone heard of a cable show called
Bullshit ???
penn and teller.
that show aligns perfectly with audio gods
if we feel good enough about using a product but cannot obtain real information about how
All that’s left is the shows name
I think all of us have bought or tried things to improve sound.
something’s do change things but to find facts it’s a mist at best yet we can hear it.
put footers on an amp or preamp
glass on tubes even a weight on equipment
these do have effects I think we can all agree ?
do fuses matter I’m not sure but I do have buds who swear as they lie to there spouses in paying for them.

 

[Gregm]

Yes, absolutely!

You know that one prong is "live" & the other is "neutral".
Accordingly, the device's power input is similarly wired. While the device will work however you plug in the power cable, the difference in sound - if any such is actually detected - comes from matching the wall plug to the internal wiring (live to live etc).

 

[SeagoatLeo]

You know that one prong is "live" & the other is "neutral".
Accordingly, the device's power input is similarly wired. While the device will work however you plug in the power cable, the difference in sound - if any such is actually detected - comes from matching the wall plug to the internal wiring (live to live etc).

Well, my friend tests the difference at the equipment for some electrical charge and finds a difference depending on the prong/input direction. One direction sounds superior to the other. Maybe your explanation is the reason.

 

[SeagoatLeo]

This is all due to Ohm's Law.

The reason fuses appear to be directional is that they are not perfectly cylindrical and the fuseholders for them are not perfect either. So if you turn the fuse around, you might get a better fit so the Voltage drop across the fuseholder is lower. You can measure (and hear) the effects of that Voltage drop, depending on the kind of equipment used with it (tubes are more sensitive because their filament circuits cool off when there is a greater Voltage drop).

You can get the same effect by simply spinning the fuse in its holder without reversing it, until you obtain the lowest Voltage drop (which can be measured by any 3 1/2 digit Voltmeter). TRY IT.

Some cables are directional owing to which end the shield might be grounded to, if at the other end the shield isn't grounded. But that directionality will have a lot to do with how well the grounding scheme of the associated equipment really is.

Power cords also experience a Voltage drop as do AC power outlets. The Voltage drop is measurable and the effect it has on the equipment used is measurable (I once measured a 40 Watt loss out of one of our amps entirely due to that Voltage drop; that sort of thing is also easily heard).

Beyond that, directionality of fuses and wire does not exist in AC circuits. If you understand engineering you know why this is so. If you don't, that's OK but at the least I've given you the tools to see how this works.

If wire or fuses were truly directional, they would heat up and fail in short order. Bottom line: when you hear differences due to fuses, fuse direction, power cords, AC outlets or in-wall wiring changes, its all due to Voltage drop and nothing else (unless there's some kind of noise or ground problem due to wiring error of shoddy ground practices).

This is what I know. In two EAR 890s, 912 and 864, all with the same style fuse holder, the superior direction of a fuse is repeatable in each of these units (same with my friends EAR units). Same within the manufacturer, such as my custom tube amps which require 8 amp slow blow fuses. SR fuses from black, blue, orange and purple all had consistent designation on the direction of the fuses (type/rating/amps) on the outside of the fuse holder to sound best. I have also tested this on various DACs and transports. Fuse direction superiority is repeatable within the same manufacturer/fuse.
P.S. I stopped using SR fuses as my friends and I now prefer the more neutral treated Acme fuses at $22/$24 a pop, (not like the new $250 SR Pink fuse or $600 white fuse-ridiculous prices).

 

[SeagoatLeo]

A lineair freq response you can determine best by measuring the speaker output with an analyser not with your ears .

A speaker cable called .....pharaoh,..... Cheops and Chefren would turn around in their grave / sarcophagus.

Ps i m not saying all flat measuring speakers sound good , its just one attribute.

And if a cable can change your freq response then there is something really wrong with it imo

Ha Ha Ha! Test to prove that I can't hear a linear from a radically nonlinear frequency response. You have no conception concerning my hearing or my numerous friends in the high end audio industry, manufacturers, recording engineers (of which I am a minor one), etc. I am telling you that my neighbors system which consists of YG Acoustic Sonya 2.3s and subs with $1/2 million in gear had the bass sounding terrible/non-linear with one note out and the next in up and down the music scale with poor imaging and thin sounding vocals. The Pangea power cables were TERRIBLE sounding. Just one high quality power cable altered the bass problem by 90%. Six of them throughout his system put my neighbor into ecstasy. I did not say flat frequency response because that does not necessarily equate to music or individual sonic taste (or that of the mastered recording). The prior sound was incoherent to the music and now it is coherent as in musically correct linearity.

GroverHuffman cables are of high quality for the past 14 years with his own (he wrote his own patent) technology and he named the models for the past 10 years Empress and Pharoah. So what? What does SR Atmosphere Euphoria X have on it wherein Euphoria should sound better than the two models above it.

Trusting my ability to turn sour milk into something tasty, I was chosen in 2005 to take assorted 1930s to 1950s various recordings and reassemble them into 11 CDs content of recordings for the Erich Zeisl Vienna centennial (Zeisl and Schoenberg were brothers in law). The prior audio engineer (well known but whose name escapes me) transfers added reverb, cut the bass, boosted the highs and overall compressed the sound (awful)! I didn't have the same near SOTA quality gear in 2005 but was able to competently transfer flat already mastered/raw tapes, 78s, LPs and transferred wire recordings into digital format for future use (also sent to UCLA and USC archives). So, I know what flat frequency response or an approximation of it is and how it relates to the sound of reproduced music.

 

[SeagoatLeo]

Yet, no one has ever heard of any equipment damage or fire or whatever due to an audiophile fuse - even though more than 120,000 fuses have been sold by the top 3 boutique fuse (as you say) companies in recent years. Faint heart ne’er won fair maiden.

Okay, maybe I won't maximize the sound quality of a $110,000 VR9 SE Mk2 upgraded speaker or a $26,000 Poseidon DAC. I think they sound darn good as is. Certainly not the $34,000 Westminster Labs REI amps. I am not going to mess with them.

 

[Geoffkait]

There is a random element in any measurement. Nothing is perfect, including a measurement system. It has finite resolution, dynamic range, accuracy, and precision, plus there will be run-to-run variances that should be assessed through multiple trials and such. IIRC the absolute accuracy and noise floor of the measurement devices was not stated in the article but I did not look all that closely. Measuring very low resistance is hard and run-to-run variations tend to be pretty high due to contact resistance, changing environmental and test conditions (e.g. temperature, supply drift, etc.), and so forth.


Were the listening tests double blind? It also matters where in the system the fuses are inserted; you are implying they are all in the AC signal path, but other threads on fuses discuss their use in the power supply from wall inlet fuses to DC rail fuses. The sub-milliohm changes would be swamped by things like swapping cables or just inserting the fuses multiple times. The range of average resistance readings, assuming that's what they are, do indeed indicate a difference in the magnitude of resistance (and thus voltage drop) for different fuses, but the directionality part is what seems suspect for a passive series component at audio frequencies. That part of the claim implies some sort of materials shift or rectification, which again points to differences in connections to and through the fuse, but the directional aspect claimed is fractions of a milliohm, which could be within measurement error.

The modulation of fuse resistance with varying current (and temperature) is well-known and is one reason things like power amps either eschew fuses in the signal path or place them within the feedback loop so any change is compensated. Your application is then only fuses in speakers or speaker cables? Most speakers I have seen only fuse the mid/tweeter sections if anything (lower power and thus lower current), and many speakers do not include fuses at all.


Current is not a pure scalar, i.e. magnitude only, except for an ideal (pure) DC current (with no noise, which is impossible except theoretically). Current flow is not constant and is phased with respect to voltage since voltage fields move the carriers (some use electrons, some use holes, in defining current flow, but the net result is the same). If voltage reverses polarity, current flow follows as driven by the voltage field, and that is back to why the term AC is used. The magnitude can be traced back to carriers, but there is also timing involved, which results in a vector quantity (magnitude and phase).

I am confused that, if current is caused by moving electrons (actually charge, in coulombs/second), and electrons change direction, how does current not change direction? If I measure current through an AC line, it clearly changes direction, and I am normally measuring at the macro (not electron) level. That is with respect to some reference, typically 0 V, of course. At the quantum level, electron flow (and thus current) driven by voltage fields does change direction with voltage polarity, by any reference I could find from basic Ohm's Law to my quantum mechanics grad texts. I suppose you can debate drift velocity vs. charge velocity and so forth but we're already far beyond what most forum members are likely to follow, or care about.

I do not see any hope of changing anyone's mind, though finding the actual reason behind audible differences when changing fuse orientation would be interesting. It would require further audio (listening) testing unlikely to be performed, however, to rule out perceptual bias.

Wow, talk about not able to change people‘s minds. This is Exhibit A - The Backfire Effect in action. As more and more contradictory evidence is presented the more tightly the naysayer holds on to his beliefs, struggling to come up with every possible defense. Science is supposed to be open-minded active search for truth, not a stubborn, unchanging, defensive Enterprise, resting on its laurels.

Your post is also an excellent example of not being able to see the Forest for the trees. You’ve looked everywhere including the sub-atomic level and you still can’t find anything. Hint: it’s right there in front of you.

you wrote,

”I am confused that, if current is caused by moving electrons (actually charge, in coulombs/second), and electrons change direction, how does current not change direction? If I measure current through an AC line, it clearly changes direction, and I am normally measuring at the macro (not electron) level. That is with respect to some reference, typically 0 V, of course. At the quantum level, electron flow (and thus current) driven by voltage fields does change direction with voltage polarity, by any reference I could find from basic Ohm's Law to my quantum mechanics grad texts. I suppose you can debate drift velocity vs. charge velocity and so forth but we're already far beyond what most forum members are likely to follow, or care about.”

I already explained current is a calculated number. Of course electrons are charge carriers. It’s a misnomer or misleading to call the circuit AC alternating current. I never said current changes direction, you did. The Poynting vector, that changes direction. It’s a vector.