Comments by "Spruce_Goose" (@spruce_goose5169) on "The Engineering Mindset" channel.

@billwilson3665 And those that can't do can't do because they were never taught. ;)
4
@OprichnikStyle Nope. You are mistaken. Electricity does not 'want to go to ground' as many have been taught. It goes to ground only because the transformer is also grounded, thereby completing a circuit.
3
@ecospider5 In theory if your ground connection was extremely low impedance, maybe. But even though the earth as a whole would serve as a perfect conductor, the connection points (i.e. your grounding rod) do not; and so you will have an added load in your return and therefor you would notice varying voltages between the two phase legs when unbalanced.
2
The 'source' rule never need 'trump' the potential rule. Potential is relative. A source internally generates a difference of potential--by definition If current did not return to the source (in time) then that implies a charge is building up elsewhere (which can happen), but this then implies that there is a new differential elsewhere that 'wants' to equalize, and it wants to do so with the source. Consider that charge, in the context of power circuits, needs to be constantly replenished--be it by a spinning turbine, a chemical reaction, or photons (photoelectric effect). Where is the charge going to be replenished from? Can it be stolen from some bank? Well if it steels charge, that 'charge hole' will want to be filled. Consider that happening on a contiguous basis and you have a continuous circuit with charge 'returning to source.'
2
@ke6gwf You are correct, but 'source' in this context is the local transformer, not the PoCo generators or whatnot. Transformer isolates the returns.
2
When people start talking about lightning and trying to compare it to residential electrical systems and charge 'going to ground,' it's usually bad news. It's not the same kettle of fish. Lighting is essentially also a form of 'returning to source.' The sources are different. The charge of an electrical system is indeed returning to source, not to ground (earth). Earth is merely a conductor in this dance. The key point here is that 'potential difference,' i.e. voltage, is between two points. The earth is not some master point of reference, it is only reference if we make it so. The potential difference is established within the electricity generating mechanisms, and isolated with transformers. I.e. the transformer becomes the source in this case. If you are curious about this, search 'ungrounded' or 'floating' electrical systems. They used to be common and looking into them might metastasize some of these concepts.
2
@nix324 Thank you, someone who knows what they are talking about. In a literal sense they are both hot, as in will show up the same under an IR camera, because they both carry current (the same current when a branch, the net current when multiple branches). And yes, have the same voltage relative to each other. I would suggest a better term for us all to apply (if it weren't for it being already used to describe the 'high-leg' of a delta, i.e. 'stingers') would be the 'high conductor' and the 'grounded conductor.' In fact, the proper terminology is not neutral in most cases, but 'grounded conductor.'
2
"And then you can add that if there's a problem..." Except the primary purpose of the EGC (ground) IS for if there's a problem (fault). It's not to dissipate induced voltage as you say. Sure it might help to keep high impedance meter readings clean, but do you actually think household current will induce dangerous voltages to metal casings via inductance?
2
I think some of the confusion is surrounding what the 'neutral' truly is. Neutral is actually not the best term here, for reasons I won't get into. The proper term is 'grounded conductor.' All you have to do is consider that it is a conductor of equal value, import, and function as the 'hot' and it should all make sense. The only difference is literally that it is 'grounded.' All that means is it's voltage potential to earth is eliminated. It is clamped to earth potential. The voltage difference between the two conductors, therefore, all shows up in the 'hot' relative to earth ground. It is actually possible to unearth the system and not have one defined as grounded at all. The voltage to ground from either wire in that case would officially be 'unknown.'
2
@wfemp_4730 who said the source of lightning WASN'T the earth? Is it because of the word 'essentially'? I think that is to cover the complexity involved here. Cloud to cloud is equalizing charge between clouds. Cloud to ground is equalizing charge between cloud and ground. No? Lightning is interesting and tough to compare with power distribution because lightning takes place on immense scales and involves STORAGE of far more charge: like a giant capacitor. Power systems move a lot of energy but they don't store charge in massive banks the same way the atmosphere can. Power systems are more of a 'pump' system then a 'reservoir' system. For a loose equivalence in power systems I would look to capacitors.
2
@ecospider5 I see what you are saying. I certainly don't see any reason not to do what you suggest. Heck, maybe it's a good idea. My point was only to clarify that the ground rod impedance will cause strange behavior on the system; behavior that is commonly observable like lights that dim and brighten (for the duration not for an instant) as other loads are switched on/off, as well as other behaviors one might observe due to over/under voltage. It doesn't necessarily require measuring voltages with equipment to see this in a lost neutral scenario. If I started noticing this, I like your idea to check the ground connection for current (after first checking to see if the neutral has obviously come loose.) The other trick would be to make sure you are not running balanced loads when taking the measurement. cheers
1
@ecospider5 another example symptom could be shocks experienced via metal 'grounded' equipment.
1
"Can't the hot simply push/pull current from the ground itself with little resistance" It sounds like you are still operating under the fallacy that charge is borne of and returns to the earth i.e. 'ground.' Charge will return to source, which in practical terms in this case can be considered the transformer on the pole outside your house. For current to be high enough to trip the breaker, it needs a low impedance path, as you seem to understand. If a hot wire is touching the earth, the path is through the physical ground to the grounding rod outside your house and/or the pole. Think of the earth simply as a conductor, not a magical source of power. Earth, taken on whole, is a great conductor due to the many parallel paths electricity can take. But in the area surrounding the hot wire fault, it is an incredibly poor conductor because it has to travel through the immediately surrounding soil. Its simply not low resistance enough.
1
This is minor, but is there a reason you show 4 lines at 6:50, all on insulated standoffs? I understand there may be a 4th conductor, but it would be the neutral and therefor not connected via an insulator. Similarly, many split-phase systems use this neutral on the primary, so the transformer would only have one line coming in needing an insulator.
1
@ke6gwf They may all be bonded to earth, but that doesn't mean the transformer circuit doesn't have a certain amount of isolation. The bonding is not to provide current return paths, I'm sure you know. The most distant 'source' (i.e. the PoCo generator) is not the 'source' that current in your residential system returns to just because they share the earth as bond. Could you describe the logic behind such an assertion? Think about the actual connections. (are you in the U.S. by the way?) In the U.S. 'split-phase' service is common. A single phase conductor is tapped, along with a distribution neutral, into the pole transformer. The house side of this transformer, end-to-end, is 240 volts. But neutral on the house side (bonded to earth!) is exactly halfway between these two potentials, which were derived via inductive measures from the distribution phase and neutral-- a neutral which is on the low end of the transformer PoCo side (not in the middle like the house side). The house neutral (0v to ground) is not in phase with the PoCo neutral. Please explain how current will handle this. Don't forget that delta connections with not bonded neutrals (actually no neutral at all) do exist, but that's an aside and not a needed discussion to get at this question. (Or maybe it will be, we'll see where this conversation turns :)
1
@ke6gwf I agree with most everything you say until the end. >"You seem to think that because one transformer is only wound with a single coil going "up" from the neutral, and another transformer has a coil going out from each side of the Neutral, that somehow that makes the Neutral different" No that's not what I am saying, but I admit that saying they were 'out of phase' was not accurate, nor was it relevant or helpful to the discussion. All I meant was that If you graphed voltage (for example), with ground as reference (x-axis) the primary coil plot would be climbing while the secondary coil plot is falling IF the 'hot' (coil end of the secondary being graphed against the center tap) is on the same end as the Primary neutral. This is to be expected when ground is referenced off the end of one coil and the middle for the other. Sorry, probably not doing a good job explaining this in words and it's really an irrelevant aside. >"any voltage changes, frequency changes, etc, created by the generator will directly show up at the house" Yes I agree. But this STILL doesn't mean there is no form of isolation. The power is coupled via induction (and sometimes a bit of capacitance I believe) but not via a conductive path. Have you heard of the term 'isolation transformer.' Isolation transformers are usually purpose built to further protect against those capacitive couplings and what not, but any transformer offers some isolation in that the conductive path is eliminated under normal operating circumstances. It sounds like you think that because the energy source is forever and always the PoCo generator (agreed) that the electrons will view the end of their circuit as the same. Can you expand on why you think this? Google isolation transformer before you do for contemplation. The PoCo generator powers the transformer, that we agree on, but the circuit in a conductive sense is isolated to the secondary. Consider a bike chain system but with multiple chains and gear connections. The chains are like the 'circuits': each link in a chain will return to it's own individual sprocket (akin to a transformer), even though the source of the power itself is input down the line at the peddles. I suppose I will bring up Delta connections again. How do explain the fact that many primary transmission lines lack a neutral altogether? Cheers, enjyoinh tjhe discussion. *Edited a million times because I can't type or formulate cohesive thoughts the first time around.
1
@ke6gwf In regards to SWER: it uses the earth return but that doesn't mean all points use all grounds as return. Struggling to find the words on that one. But look on the Wiki page. See the diagram? Shows a pretty clear return path through the ground but only within one transformer circuit. Is that diagram just choosing not to draw the lower voltage returns because they are insignificant? Or because they are not there? (I argue the latter, you the former I imagine). I still don't understand why you think a system sharing common bonding (to earth) somehow makes it all connected in the way you think. What about separate grids? They all share the same common bond to earth. Are you arguing that current will roam around the planet from one grid to another just because they're all connected to earth? Take some simple home portable generators as an example: If I was running a generator and you another down the street and we both bonded them the earth, are you saying that a hot line touching the ground would allows cross currents between the generators?
1
@ke6gwf There's a lot going on in this latest reply of yours but it's all missing the point. I don't refute that current can travel via the earth. You've continually put words/ideas into my mouth and grossly misunderstood the point of my questioning and my analogies. I have not done a great job getting to the heart of the matter however, so I don't blame you for the rambling thread. Talking about 'isolation' was truly the wrong way to go about this. My apologies. It is simple: Kirchoff's Current Law. Draw the circuit, apply Kirchoff's Current Law, and get back to me on how current leaving one end of the transformer coil will NOT return to the other end. If you can answer that, you have my undivided attention.
1
@ke6gwf glad we're on the same page now.
1
If I understand your question, no oftentimes only 1 is a 'phase conductor' and the other is grounded and neutral to the 3-phase system.
1
No. It is the full potential of the coil. 240 volts. Not sure if you are in the U.S., but this is where the 240 volts that run certain appliances (e.g. electric range) come from for the U.S.
1
@robertbrandywine We need to separate voltage and current in this discussion. Current flows through the circuit, and so yes, the 'neutral' has just as much current as the 'hot.' (Unless we're talking the main feeder neutral, in which case it carries the difference between the legs). Voltage, on the other hand, does not flow through the circuit, it exists between two points. Take that to heart. It very much needs two defined points, and where you measure those two points can change the reading even if current is constant. The voltage drops across the load. The key bit here is that the 'neutral'— which should really just be called the 'grounded conductor'— is only not 'hot' because it is intentionally grounded. This clamps the voltage to earth potential, which happens to be pretty close to the potential you and I are at when standing on the earth, as we do. So does the neutral have voltage? Well that's an incomplete question. Voltage between which points? To ground? No, not really. To the other 'hot' conductor? Yes should have about 120 volts. But remember that the 'neutral' (or grounded conductor as preferred) is only NOT HOT if it is in direct and low impedance connection with the earthed portion of the system. If you disconnected a neutral wire from the panel and grabbed ahold of it, suddenly you are a load in the circuit and the 'neutral' is actually a hot because you've disconnected it's clamp to ground by disconnecting it from the panel.
1
@robertbrandywine indeed.
1
@CodyLynn100 It doesn't matter which way he shows the battery. Neutral really wasn't properly defined in the video, but Neutral sure as heck ain't one pole of a battery, regardless of whether you pick the negative or positive pole. It also sure as heck is not 'ground,' which has several definitions but in this case can be used to mean both 'earth' and 'reference' (earth, assuming we are talking about actually earthing one conductor, which he didn't actually do in the initial battery diagram). In an AC circuit, current flow (whether conventional or electron) reverses every half cycle. Neither 'neutral' nor 'ground' nor the type of current flow notation has anything to do with that. Current doesn't 'flow' from hot to ground or visa-versa based on polarity or based on the net charge of the 'earth'. Current doesn't 'flow' to or from the ground (earth) at all in the context of residential circuitry, aside from in completing the circuit back to the transformer. Earth is essentially another conductor in this case. Perhaps I've misunderstood your point, and if so, I apologize.
1
You are right it will not trip the breaker, but no it won't electrocute you, assuming it's in tact. If its on the neutral side of the load, its close to 0V, and so the casing would be close to 0V. If everything is wired correctly and in proper working order, a grounded metal case essentially IS touching the neutral (not technically due to wire resistance, but it's pretty negligible). If, on the other hand, the neutral was open, the situation is different, and you could very well get electrocuted (though the EGC would also have to be open in this case, or lack one altogether). In this situation, a 'neutral' faulting to the case would more technically be a hot fault, even if the wire doing it was white. Takeaway: open neutrals are dangerous. Don't ever touch neutrals without instrument verification!
1
'hot' is neither negative nor positive. 'Hot' is simply the conductor that has electric potential (voltage) to ground (earth) because the other conductor in the circuit (so called neutral-- or more properly the 'grounded conductor') has been grounded. By 'has been grounded' we mean that it's potential (voltage) has been brought into equilibrium with that of the local earth's. It really has nothing to do with 'positive' and 'negative.' Remember that it's AC and 'polarity' switches every half cycle (120 times a second in the U.S.).
1
Are you talking about a 240 volt circuit? I think he was referring to cancelling current on the main neutral drop, not the branch neutrals. The main neutral drop should be sized to handle a couple circuits running off the same phase without a balanced load opposite.
1
Flip the situation and you've got it. (Lighting is going back to its source when it strikes)
1
No. And no it won't trip a breaker either, but some current will flow on the grounding conductor (green/bare copper) back to the panel. Many old wiring basically did this intentionally when they did what's called a bootleg ground. Not good but it doesn't immediately present shock hazard or trip a breaker. The neutral carries current and in that sense is just as 'hot' as the 'hot,' but it is grounded and so voltage to ground stays at zero (if the system is working), even though the current is alternating directions.
1
Well, there's a reason that we decided to start grounding(earthing) systems, so I'm not sure your comment 'if you want real safety...' really holds to scrutiny. You are right that at first glance it seems to make many common electrocution scenarios safer, but then other 'scenarios' crop up, such as stray voltage. Perhaps that sort of thing is the 'fundamental purpose' you refer to?
1
Furthermore, it 'anchors' metal equipment casings at near 0V with respect to earth, but reference to earth-ground is actually quite irrelevant to its primary function of returning fault current to the source. What IS relevant is that it provides a low impedance path for the fault current back to the transformer (source). The notion that charge seeks to return to source (not earth) should be one of the main takeaways from this video. Indeed, an EGC can indeed be utilized on a floating system with no tie to earth ground at all (such as in his example with the 'ground' added to the battery system. No where was it connected to earth)
1
It's arbitrary. AC voltage cycles at 60hz and yet the 'hot' always remains the same wire, regardless of polarity. It has to do with reference.
1
Another point that may help clarify here is that 'current' is not analogous to energy. Power is voltage x amperage. Could the power company deliver power without voltage? No. 0 times any number is 0. When a 'load' is in a circuit (i.e. any electrical device you are running at home), you are provided with a near constant voltage. If this voltage wasn't maintained, the capacity to deliver power would drop to 0 as current flows and voltage drops towards 0. A water analogy: Consider a water slide with a pool at the bottom, and the water gets pumped from the pool to the top of the slide. The water returns to the pool (to the source) after running down the slide. Does that mean it doesn't require energy to pump the water to the top of the slide? Of course not. It takes energy to establish that 'potential' in the water, i.e. to pump it to a higher height from which it can then 'flow' (as current does) back to the pool where it began (source). To keep that steady flow (current) of water, the pump must continually pump water to the top (provide the energy to establish potential difference).
1
Different values of CURRENT? Do you mean charge? What happens if you take a positive terminal of a battery and connect it to ground? OR maybe the negative? Is there a potential difference between any one of those terminals and ground? And so will current flow? Potential is relative.
1
@dominiquefortin5345 Have you ever tried measuring the current of that 'transient'? Do you suggest it is a measurable amount of current? Perhaps akin to the amount of current that would flow from a completely dead-ass battery terminal to ground? As in a static equalization and not at all related to the battery's internal voltage? DO you see what I'm saying? Can you specifically describe a situation in which current is NOT returning to source? I don't understand the fundamental assertion you are making. If there isn't a return to source it would imply a banking of charge elsewhere and an imbalance in the system which will seek equalization.
1
It doesn't. It takes ALL paths, proportionally to resistance. Think of a white water river. How does it 'know' where to flow. You could perhaps say 'gravity' or perhaps something like 'the shape of the river creates "walls" that retain the flows and "low spots" that channel the flow. Insofar as you can say 'gravity' for the water example, perhaps you could say 'electromagnetic' force for current flow. And insofar as you can say the "walls and low spots" retaining and directing water flow, you could say 'elements with high electrical resistance block, while elements with low electrical resistance (high conductivity) channel the flow.'
1
If you don't mind me asking, how do you do your animation's? Very nice.
1
@robertbrandywine "But where the neutral is connected to the load there is a 120 V potential between that point and back at the middle of the transformer." Well, not really 'that point'. The voltage drop occurs across the load. But I might be getting nit-picky, I think you have the right idea.
1
@cursed_multicel I'm in the u.s. and not that familiar with European systems, but I believe they make 230 volts between a 'hot' and a 'neutral' (grounded conductor). So one ungrounded and one grounded. Which is different than u.s. where we make 240 between two ungrounded. (u.s. being split phase, europe being a standard single phase, where phase conductor to phase conductor (hot to hot) is 400 volts nominal.)
1
You are right. Technically it's the 'grounded conductor.' Neutral really has more to do with the 'neutral component' of a system. Many argue that the so-called 'neutral' is not the neutral of a 120v circuit, but the main feeder IS indeed the neutral of the split-phase system. Just think of neutral as the center of a circle, or the balance point of a see-saw. Current will not flow along the neutral in a perfectly balanced system. But most of the 'neutrals' feeding the branches of a residential 120v circuit are not really neutral in that way, and it's best to think of them as 'grounded conductors.'
1
@thead9 I think he's just saying its a low resistance path (or low impedance) for fault current, as opposed to a path through the ground or other loads (e.g. humans). Even a ground wire of slightly smaller gauge is a low resistance path for return current compared to through loads.
1
If DC is more intuitive to you, perhaps also check out 3-wire Edison circuits. While they don't deal with phases, the concept of a shared neutral carrying unbalanced load current applies.
1
Give us your explanation. No doubt saying 'the source of lightning is essentially the earth' does not do lightning justice, but why is it insufficient as a follow-up to the statement 'electricity wants to return to source.' ? Do you disagree with that latter statement. If you don't, then how do you square it?
1