Comments by "Jovet" (@jovetj) on "The Engineering Mindset" channel.

  1. Key point I think was overlooked: the more electrons in the outermost shell, the stronger the nucleus holds onto them. This is why materials with just one valence electron (living in the outermost shell) make the best conductors of electricity—they are the loosest held by the atom. Valence electrons even make the atom smaller.... an atom with two valence electrons will be just slightly smaller in diameter than the atom with one less proton/electron: the nucleus holds the electrons tighter and closer, which makes the atom's diameter slightly smaller. The metals copper, silver, and gold are excellent conductors because they have one valence electron and the size of the atoms is a "sweet spot" for how loosely that valence electron is held.
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  2.  @onichan924  Yes, their precise location in space is probabilistic, but the probability outside of those shells is practically zero.
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  3. Capacitors and Inductors do the same thing.... they store energy. Capacitors use chemistry to make a small electric field to store up electrons. Inductors store energy in the form of a concentrated magnetic field. Both take time and electric current to "charge" but behave differently once they're charged. A capacitor acts like a resistor once it's charged, but an inductor acts more like a straight wire once it's charged. When power to them is removed, they then begin to discharge, assuming the energy they've stored has somewhere to go. Both discharge at different rates/profiles.
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  4. The only other thing to add might be the professional trade/code difference between grounded conductor and grounding conductor.
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  5. The first scenario provides a neutral in the switch box by default. That isn't what the Code change was designed to address. The Code change addresses the second scenario, where no neutral is sent to the switch box because the black and white wires are a switch loop to control the light. The third scenario shows how it shall now be done, according to Code, with a neutral wire in the switch box even if it is not used at installation.
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  6. It's a bit complicated to explain (let alone understand), but in the simplest sense the electrons are moving too fast to actually collide with the nucleus. In this sense it's like the Earth: the Earth is moving too fast around the sun to be pulled into it. But, unlike the Earth, the electrons around an atom's nucleus are a cloud and not distinct particles. Each electron is "everywhere at once" in its shell because its actual energy is a compromise between the kinetic energy the electron has and its potential energy with its charge attraction to the nucleus. Quantum mechanics has all the details.
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  7. If the two-wire cable was installed when the building was built, it will be anchored in too many places and will be impossible to do what you are suggesting. But, it is possible to run a new 3-wire cable and remove the 2-wire cable from service.
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  8. Get your thinking straight. A white wire is a neutral OR a hot/phase. It cannot be both. By default, white means neutral. If it's reassigned to be a "hot" wire then that's when it gets the black marking. This has been done for decades because it's cheaper. But it is no longer allowed in new installations except in specific circumstances, because future-proofing.
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  9. Yes, more or less. But because electrons are not an easily defined and finite "particle" but more of a "cloud" they are also almost everywhere around the atom (at their energy level) at once. Quantum Mechanics is deep stuff.
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  10.  @alimohammad7799  If the switch is in the neutral? It's against code to wire a switch into a neutral wire. So, don't do that.
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  11. It doesn't matter.
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  12. Alternating current changes polarity, usually 60 or 50 times a second. In one instance, the "hot" wire is (+) and the "neutral" wire is (–). 1/60th of a second later, the "hot" wire is now (–) and the "neutral" wire is (+). Imagine taking a battery and flipping it around 60 times a second. It's kinda like that. It's also why polarity is not a "thing" in AC circuits... it's never constant!
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  13.  @jordansutche9829  It's a key point for the why. Not the how.
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  14. In the third example, it's better to use Black for sending power to the switch loop, and red for the switched hot after the switch.
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  15. @Ironbuket In typical DC wiring, yes, Red is (+) and Black is (–). In most automobiles, the frame (or frame ground) is negative. There is no neutral, but there could be if you connected two batteries or cells in series and had a third connection between them (e.g. here the + and – are connected). Electrons are negatively charged, so they are drawn to the positive terminal. May be weird to think about at first, but it's accurate. With AC, there is no polarity, so (+) and (–) doesn't apply. Thus, wiring colors are pretty arbitrary. In North America, any wire color that is not white, gray, green, or bare should be considered a Hot. And a "hot" conductor is one that is not grounded. If it's grounded, then it is conducting current in the circuit, but it also is at the same voltage potential as the Earth.
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  16. There are three versions because sometimes it's convenient to route the power from the service panel to the switch and then to the light... and sometimes it's more convenient to route the power from the panel to the light and then to the switch. For going to the light first, the second version is no longer legal, but is still perfectly safe. The third version is the way it should be done now, to comply with Code.
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  17. A regular switch, sometimes called "two-way" has two terminals. When it's ON the terminals are connected; when it's OFF the terminals are not connected. A "three-way" switch has three terminals, and must be used in pairs to provide two switching locations. A "four-way" switch has four terminals, and can be used with two "three-way" switches to provide three or more switching locations.
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  18. It's not very bad nor dangerous, and certainly not crazy. It's inconvenient sometimes, that's all.
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  19. The neutral and the hot do not switch places. A "hot" wire is a conductor that is not grounded. Most neutrals are grounded. In AC, the polarity of the circuit is constantly fluctuating. One moment, the "hot" is (+) and the neutral is (–). The next moment, the "hot" is (–) and now the neutral is (+). And then, the next moment, they've flipped back again. This happens constantly. Because the neutral is connected to ground, the neutral and ground are at the same voltage potential no matter what polarity is active. Once a circuit is turned off, no power flows at all. Not through the hot, and not through the neutral of that circuit.
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  20. Hard to tell why. If you're not careful, when installing the switch into the box, the bare ground wire can come into contact with one of the switch terminals, causing a short circuit. If there is more than one cable entering the box, then the white wire you connected may actually be a neutral wire, not a hot wire. (Was it marked with any black, as shown in this video, like it's supposd to be?)
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  21. Electrical code requirement. Futureproofing for potential "smart" devices in-wall.
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  22. Remember that some of the wire colors will vary. He showed some of the white wires (with black tape) being used to connect to the common terminal, but others might use them as a traveler.
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  23. That part of the video is a bit confusing, because you're right. Most automobile systems in North America are negative-ground. (Also keep in mind that this is FRAME ground, and not EARTH ground.) The video does correctly depict electrons moving from the negative to the positive terminal, however. I think the video is trying to make a comparison to from the simplicity of a battery to the way a circuit in a home is setup, but it fails with the nuances of DC polarity.
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  24. It isn't a popularity contest. It's a function of practicality and economy. Cable and wire are expensive, and installing it takes time, so you want the shortest, most-efficient runs possible. The physical layout of the structure and the electrical device locations to meet that goal are how the method is chosen in a given situation.
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  25. Electrical boxes are required by the Electrical Code.
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  26. *common All the wires on a switch are "hot" (except the ground wire, if any).
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  27. https://youtu.be/opoEswRp_jg
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  28. @Raymond Ray There's nothing wrong with circuit #2 shown in the video. The reason it's now illegal is because of the pain of adding a neutral to the switch box if it's needed in the future.  @jonburhan5478  Always turn off the power. It's sorta like looking both ways before crossing the street.
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  29. “Because the neutral coming from the light and going into the second switch box is now re-identified as a hot” Let's be precise with our terminology here. If it's a Hot, then it is NOT a Neutral. The white wire running between the light box and the second switch is not a neutral, even though it is white. That's the reason for the black markings—it's a Hot wire. The neutral in the circuit shown goes from the service panel, in and out of the first switch box, and then into the light box to the light fixture. Yes, it is a Code violation (for both Options 2 and 3 shown in this video) for locales enforcing the "neutral in every switch box" requirement. The simplest solution is to run a second cable out of the second switch and back to the light, and in that case you don't need the travelers going through the light box at all, and it becomes just like Option 1 shown.
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  30. To have more than one device (e.g. light) be switched, you'll have to run additional cables to the additional devices.
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  31. A circuit is formed when there is a continuous path for electrons (or electrical potential) from a power source around and back to that power source. The power source is like a "pump" which recirculates the electrons continuously, as long as current is flowing. If the continuous path is ever broken, then all electrons stop flowing in the circuit instantaneously. A short circuit is when the contiguous path is very short and offers little to no resistance. This is bad because more energy could flow through the circuit than it is designed to handle (wires could melt) and/or it could destroy the power source. To be practical, electric current needs to flow through a resistance, called "the load," to do some kind of work. The load is the natural limiter of current flowing through a circuit, and can be anything from a light to a motor or so on.
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  32. It's future-proofing for smart devices that is now required by Code. Just because it's not required at construction doesn't mean it won't be needed later.
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  33. Not legal.
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  34. 240V circuits are just like 120V circuits, except there are "two hots". Either hot and the neutral make 120 volts. But the two hots connected to something without the neutral make 240V. You only need the two hots for a 240V device, like a water heater. You need the two hots and the neutral for a 240V/120V device (it uses both voltages), like a clothes dryer or an electric range.
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  35. Three-way switches are very common. As doug m wrote, they're used when you want to control a device (such as a light) from two or more different locations. For more than two locations, you start adding four-way switches in between the two three-way switches. ANY of the switches can change the state of the light.
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  36. 3:49 I winced at the "LED Light Bulb" bit.
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  37. It's not complicated. It's exactly the same as the second way, except that the neutral wire that stops in the light box in the second example also goes down to the switch box, even if it's not being used yet. It may be needed later.
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  38. A "Hot" or "live" wire is a conductor that isn't grounded. That can be earth ground, or frame/chassis ground. The term "hot" is not usually used with isolated DC circuits, although it can be.    The majority of direct current (DC) systems people are familiar with are (–) ground, but (+)-ground systems exist, too. It doesn't really matter, as long as it's known and consistent within a system. Polarity matters in DC.    Alternating current (AC) does not have static polarity, so the idea of (+) and (–) doesn't apply. Either a conductor is grounded, or it isn't. Remember that electricity only flows in a complete loop, called a circuit. If there is no complete loop, then electricity will not flow. DC always flows in a persistent direction, but AC changes back and forth (alternates polarity) and this happens throughout the entire circuit (not just the "hot wire").     Atoms cannot get a "surplus of protons." Atoms want to be neutral, which means a balance of protons (+) and electrons (—). Atoms can become unbalanced by temporarily losing or gaining electrons, and such atoms are called ions. Atoms can only gain protons by nuclear fusion, which is what happens in the core of the Sun, or nuclear decay.  "Hot" or "live" conductors are special only because they are the parts of the circuit which are isolated from the grounded path. There is no voltage potential between the grounded conductor and the ground system itself because they're connected together. The "hot" or "live" is switched/fused because it's a lot easier to further isolate what is already isolated. Plus, it reduces further problems and dangers of accidentally interrupted neutrals. Not all AC circuits have a "neutral" as that really derives from the middle tap of a secondary winding on a transformer. A power source works by inducing a voltage potential in a conductor through a complete circuit. On a battery, the positive terminal isn't more or less "active" than the negative terminal. The two terminals just have opposite roles. One is going to accept electrons, and the other is going to donate them. 9V or -9V is still 9 volts of potential, no matter how you measure it. No one terminal of a power source is "more important" than another, because there still has to be a loop.
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  39. @kal9001 Yep. Much safer to have a carefully-controlled "hot" and assume everything else is the same potential (ground, or negative). @Pqrst Zxerty Most general DC power source wiring is red and black, so by that logic, the white wire should be black, too. But, remember, that (+) is only the red wire in (–) ground systems. In reality, the black wire represents (chassis) ground, and the red wire represents not-ground. So, in a (+)-ground system, the (+) would be the black wire. So, the video is more-correct on that point, even if it's just something most people are not used to. Excepting it's a white wire, not black. I think it would be less confusing if the (+) and red/black wires were employed as usual, and the current was still just shown to flow (–) to (+).
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  40.  @DeepCZero3  Positive grounds are still around in the telecommunications industry as well.
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  41. Yes, it's not legal for most new residential installations. Using 14-3 is the solution, as shown in the last example on this video.
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  42. A "traveler wire" only exists between two three-way switches. The wire after all of the switches to the light(s) is not a traveler.
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  43. Static electricity doesn't work the same as the electricity we generate with batteries and power plants. It's still a "flow of electrons" but that's about all they have in common. When you use a power source, you're setting up a prolonged voltage potential between the terminals on that power source. For example, a 12 volt battery will have a 12 volt difference between the + and – terminals. That difference is maintained as long as the chemicals in the battery can. When you rub a balloon on your hair, you're not creating or using a prolonged power source. You're causing electrons to be casually shed from one object onto another. This happens because all objects are "solid" because electrons (like charges) repel each other. The rubbing increases the chance that this electron-electron interaction will cause some loosely-held electrons to be ejected into the other material. Atoms want to stay neutral, after all, so when those few electrons leave, the atoms left behind become slightly positive. A static electric discharge is simply the return of those extra electrons back to where they belong. As air molecules move around, they rub together, and rub against the Earth, they transfer electrons just like your hair and the balloon do. Lighting is the static discharge between the charged air molecules and the Earth. So, in way, you can think of static electricity as a "flow of electrons back to its source (source atoms)," but it's more of a quick neutralization...not the sustained flow we typically think of as electricity.
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  44. Luckily, with videos on the internet, you can pause them, and re-watch them, at will.
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  45. As he said, you wired them in series. Once you're out of the last 3-way switch, that switched hot needs to go to your light or outlet. If you have more than one light (or outlet), then you need to run additional cables to each light and connect them all together (all the hots together, and all the neutrals together).
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  46. No connection guide should be needed. 2-way switches are as basic as they get.
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  47. @philip duffy That depends. If you want a wall switch for each the light and the fan, then yes, you could do that: send the power down one of the wires, and then send the switched power back on the other two. But, if you only want the light switched, especially if you want to use a pull chain on the fan for the fan control, it's easy to send the fan constant power from its box, and control the light with the existing circuit and switch.
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  48. If by "crossed" you mean reversed... then the switches will still operate just fine. It doesn't really matter. The way it's shown, the light will only be ON if the handles are the same (up-up or down-down). If the travelers are reversed somewhere, then that may not be the case, but it won't really affect the operation any because all of the switches will still work. If by "crossed" you mean accidentally connected together... then all the switches in the circuit before that crossing become useless and won't do anything.
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  49. And 4-way switches are cross-wired DPDT switches!
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  50.  @nikkimalones1324  The names used in the USA and in Europe and the rest of the world, are different. From a European context, yes, a one-way switch is the same as a regular switch in the US. In formal terms, a regular switch is SPST (Single-Pole, Single-Throw) while a "3-way" switch is SPDT (Single Pole, Double-Throw) and a "4-way" switch is a cross-wired DPDT (Double-pole, Double-throw) switch.
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