Does Current Flow on the Neutral?

what's going on my friends i'm dustin stelzer with electrician you today we are going to talk about whether or not current actually travels in a neutral conductor [Music] now before we get started we offer continuing education yes we're approved in a whole bunch of different states you can go to electricians.com click on the little bar on the right go to continuing education and we have a bunch of different states we have more states that we're adding so if you don't see your state soon enough i promise we will have it we're spending all of 2022 pretty much trying to make sure that we're in as many states as possible but it's dope you just get to watch videos of me doing this then we have ground just says the earth and you get credit for it so check the link out below hope to see you in class all right so the reason for this is that there's a bunch of uh people out there depending you know certain environments they'll have conversations and they're like well trav you know current never actually travels in a neutral and it's like well yeah it does or some people like yeah it does no it does sometimes it does so let's break into that a little bit and see kind of what we're talking about so imagine that we've got an electrical panel and we've got our lugs these are our two hots and this is going to be our neutral bus say up here we've got a big canister uh you know a light pole we've got our primary side and we've got our secondary side coming out of there i probably should have just pre-drawn all of this sorry just bear with my drawing we hook a red wire black wire right there we've got a neutral that gets tied to the neutral point i'm going to like hop over that right there and the neutral point we're going to pretend that that's in the middle i know it's not in the middle it should be in the the exact middle that is the neutral point uh in between the two phases these are going to be like spots for breakers inside of the panel this is single phase say we've got a light bulb and that light bulb we're gonna hook up to uh one of these breakers let's just say that it's a red so we run a wire from our breaker to the bottom of the screw shell and we also have a neutral right neutral comes off of the screw shell itself comes back hits the neutral bus all of these reds are connected black there sorry i should have pre-drawn all of this i'm finding out now okay so we have a complete circuit right we've got current that can come through here go all the way out to the bulb neutral back we have a complete circuit alternating current's going to alternate back and forth 60 times a second which is going to appear to just be solid power but it's actually pulsing power so the question is in this instance with one load hooked up to one side one phase of this circuit is there actually current flowing well yeah i mean anytime current flows you have to have a complete circuit when current flows it actually means that there are electrons inside of this circuit that are moving and electricity is not just the movement of electrons electric current is the movement of electrons but there's electric power as well there's a lot of different terms within what is electricity but it's not just one thing there's a whole new whole bunch of different things that are happening so if you have a conductor um we'll say red conductor we have a a wire well there's all these little atoms that make up what a wire is so there's not actually an outer layer of any material it's all in a microscope it's just a whole bunch of atoms packed together each one of the atoms has a little electro electron on it and these electrons flow through the medium so the electrons leaving their atoms and going from atom to atom to atom that is electric current so that flowing happens when you have a completed circuit so a light bulb turns on because we have current flowing and it's a complete circle so it goes through the red all the way through the neutral current flows in the neutral for sure what happens when current flows is that there are these uh electromagnetic fields that are generated around the uh charges right so each each electron is a negatively charged particle and around the particle itself is actually a field which moves with the particle so with the movement of the particles themselves there's the movement of the fields if all of these electrons are like moving their way through in one direction all of the fields around those conductors each one has got its own field they make up this gigantic field around the wire because they're all additive together and that field also moves so there is the particles that are moving and there are the fields that are moving and it's really important because when you take like a magnet and you bring it up close to a wire the invisible field around that magnet interacts with the invisible field around the particles themselves and that's what makes the particles move so the field is important just as the particles are important now that's kind of a bit of a digression but once we get into looking at this they'll see why that's important so now let's draw another load we'll say that it's the exact same light bulb we got two of them in a pack from home depot and they're both rated the same thing we'll say that this is like a two amp bulb and this is a two amp bulb probably not real numbers but we're just trying to use something that we can kind of conceptualize uh we'll say we're gonna come off this breaker we're gonna hit the bottom of that bulb we're going to come out with our neutral make a return back to the same neutral bus so if we have two different bulbs on two different circuits right we have this phase and we have this phase is current flowing on the neutral the loads are balanced so what it means is that on this red wire we have two amps we can actually take a multimeter and check and clamp over it and we can see yeah there's two amps flowing through that conductor then we can come over to the black one and put our clamp around that and say yeah we have two amps flowing through that one as well so this is the kind of cool part if these fields you're seeing somebody like drop uh you know two different like uh two rocks in water each one kind of dissipates current right like the the the force outward of all of the lines of uh current kind of intersect and at a certain point the energies can cancel each other out so that they don't continue doing anything so the same thing happens when you have fields that interact with other fields if you have a field that's coming from one direction it's a wave and you have a field from another direction it's a wave they're going to cancel each other out they can add together two there's different things that they do just depending on the situation but in this case we have a cancelling out effect so the two amps of current that's coming through is still going through here and getting back to the neutral bus and the two amps from here is getting back and going to the neutral bus so it depends on where you're looking to see whether or not current actually flows right here if we took an amp reading we would have two amps right here it would still show two amps right this is still part of the circuit so there's definitely current traveling to get to this point same thing here we test two amps two amps current is flowing in the neutral what's interesting is when we take a current reading up here that is where we're gonna see the current disappear on these neutrals basically our circuit our actual circuit is this black and this red that is the circuit we take a neutral and we tap the middle point of the circuit which allows current to kind of flow in these miniature loops of these 120 volt loops within the big 240 volt circuit but all of the pushing and pulling is happening in that 240 volt circuit with these two different phases so where does current actually travel in this instance when we have two two loads so say we've got current that is going through red to the first light bulb and then it's going to neutral it's coming up here now ordinarily with just one circuit on it would continue to go back up to here and make a complete circuit but what we're saying is that current's not flowing we're actually reading no current so let's look at the other one we've got the same thing coming out of here we've got current flowing down through black going to the bulb still current but we're going to read here right because there's nothing that's interacting with it there's nothing that's that's going to cancel anything out but what's interesting is once we get right here it cuts off we don't have any current flowing because the combination of both of these is forcing uh the while the red is pushing the black is pulling right so if we have pushing current coming through this neutral and we have pulling current coming through the other neutral we have this kind of like pushing and pulling thing happening at the same time so wouldn't that mean in our situation over here where we've got all of these electrons moving that we would have some electrons kind of traversing relatively one direction and we would have some that are kind of moving relative the other direction well if that were truly the case we would have current going in both directions so it would show additively that there's more current passing one single point in time and there's not we show zero current completely dead nothing so what's happening is the fields around here are interacting with each other and completely canceling out and when a field is interacted with that's what makes the particle move so if the fields are dead there's nothing moving then the particles themselves are not moving as well so we basically have just created an insulator it's still conductive but there's no ability for current to flow down it so it becomes literally a dead wire so no more current is traversing this path so now the path since we're not able to traverse this little piece of neutral comes out here goes up through here comes out through here goes back through neutral comes back and goes out and that is how it's making its complete circuit it's making a complete certificate through two of these different loads instead of through this dead piece of wire that's not able to pass any current the reason that your multimeter shows that there's zero current being passing is because inside of that ammeter you know like say this is your clamp on amp probe there's a little line here and a little line here there's actually something that is sensing the magnetic field around the conductor that is running through that thing it's not sensing a magnetic field so there's not actually any movement there's nothing happening to produce that expanding and collapsing magnetic field so are we really saying that like it's going through one load and through another load just to make its way all the way back and these are conductors it's conducting current's gonna take all paths that it can to get from source back to source so it's absolutely going from one phase all the way through the circuit so it just goes to show that there's not actually any current flowing in neutral in this case when you have two completely balanced loads now let's look at it a little bit different way so if we look at a circuit diagram this is what we essentially had right we have a panel we've got uh well i guess that's the transformer really but you can think of it just as the panel is the the circuit so if we have a 120 volts here we have 120 volts here if we have a push and pull that's going on this entire circuit i'm already on yellow we have this that's happening over the large circuit but within that circuit we also have this that's happening right if a push and pull is happening here and we connect the middle points well a push and pull is still going to happen here at the same time while this is pushing and pulling this is also pushing and pulling because we have an overall push and an overall pull on the black and red so if we cut this wire out completely we're still going to have that overall push and pull and instead of having all of those loads where we have like a red over here where we've got a pulling happening and we've got a pushing happening on the white while we have a pushing happening on the black and pulling happening on the white you notice there's a push and pull happening on the white so current cannot travel right it's basically opposing each other that's it's it's something that is opposing the current flow so nothing's able to travel so the only other way that it has through the circuit to make that completed loop is through the 220 but what that does is instead of just having one load in a 120 volt circuit it takes two loads of equal size and puts them in series in a 240 volt circuit which still allows them to operate at the exact same level that they would if there were only one of them at the 120 volt level another interesting thing to note is say we didn't have a black and red instead we just had two blacks coming out of our panel well this is where we would have a doubling up of current on the neutral from what we would have on each one of the legs so if we had uh you know 10 amps flowing here and we had 10 amps flowing here well the circuits are on the same phase so we have a pushing that's happening here we have a pushing that's happening here and we have a pulling from both sides going the same direction so we're actually going to have 10 amps going out 20 amps coming back because we have 10 coming out from our source going through our loads and double of that coming back so we would end up having uh 20 amps flowing on that neutral that's why it's really really important to not stack a whole bunch of loads on one phase especially if you have like a multi-wire branch circuit or something like that where you have two ungrounded hot conductors going out into a load that are sharing a single neutral you need to make sure one is on red phase and one is on black phase so that there's not any uh excess current but if you have both of them on black phase you're going to double up the current in that neutral and you could eventually just melt all of the insulation off of that neutral if you don't think about it especially when you have non-linear loads and things like that to consider now one more thing that we can do that's probably pretty important to do to justify the case that i just made is to look at the math so if you look at ohm's law and we look at the relationship that resistances have to current flow basically a resistance is something that opposes the flow of current so the more resistance that we build up in a circuit the less current can flow all the way to the point where too much resistance acts as an insulator and no current will flow if we have zero resistance so much current will flow that we end up in a dangerous situation so in the case where we had one bulb and we were saying that we had 120 volt circuit well how much current did we say was going to flow we said it was going to be 2 amps right so if we look at the math uh for this we're using resistance so we're using e equals i times r that's ohm's law it's saying voltage equals current times the resistance we know we have 120 volts we don't know what our current is we're saying it's two but this is to check the math we've got 60 ohms of resistance so 60i we would divide out 60 to cancel that out move the 60 to the other side because we're trying to balance an equation anytime you do something on one side of the equation you have to do it to the other so 160 divided or 120 divided by 60 that equals 2 amps so on this 120 volt circuit with one light bulb we have two amps of current flowing through it there's only one resistance there so in the case that i just made saying that all that current is going through the 240 volt circuit now you're thinking well shoot we're running 240 volts through these bulbs like aren't they gonna just blow up no because we have the added resistance we're doubling the amount of resistance even though we're doubling the amount of voltage the current is going to lower so anytime there's there's a relationship that these figures have that basically says that there's an inverse proportional relationships and there's directly proportional relationships so look what happens if we run 240 volts through these because now we no longer have a neutral right we said no neutral is hooked up and it's flowing back to the panel that the current is actually flowing through both of the loads through both of the light bulbs before it makes its completed circuit so we would take 240 sorry 240 times i or i'm sorry equals i we don't know what our current is and then our resistance is double because we have twice as many so we have 120 ohms well take 120 out to leave i by itself divide 120 on both sides and we still get two amps so that's saying that there is either way in a 240 volt circuit with two loads that are the exact same or a 120 volt circuit that has one load we're gonna get the same amount of current flowing and if that wouldn't be the case if we had 120 volt circuit and we added two 60 amp or a 60 ohm loads two resistances in that circuit this would not be the same but since we're doubling our voltage and we're getting 240 volts now and now we can have two more resistance or an extra resistance basically and we'll get the same amount of current flowing through that circuit then mathematically we can do one more thing just to double check this and make sure that this is all sound we can do the power formula so we have ohm's law which is the resistance uh current and voltage relationship and then we've got kind of a reduced version of joules law which is power and voltage and amperage it doesn't take into account resistance but we can still do the same thing so the equation for that is power equals current times voltage so if we have our power in this 120 volt circuit we've got a 100 watt light bulb then we would have 100 watts equals our current we don't know what our current is and these are just random numbers so we're not going to get the same values but the values between these circuits are going to be the same so i just want you to know that ahead of time times our voltage 120 when you take 120 cancel it out divide by 120 you end up getting 0.83 repeating so we'll just say uh 0.8 amps now what if we put two 100 watt light bulbs into this 240 volt circuit so we're increasing the amount of wattage because we have two bulbs each of them is burning at 100 watts so now there's 200 watts but we've also put it in a 240 volt circuit so same thing we would have 200 watts for our power equals our current which we don't really know guessing it's going to be that times 204 volts this time so we divide out 240 240 and we still get 0.83 amps 83 repeating so either way it's going to say if you have two loads and they're equal loads we have 100 watt 100 watts same resistances if we increase the voltage and run that full 240 volts through those two loads whereas we were just running 120 through one of those loads the uh the the fundamentals of that circuit the actual uh what is going on in that circuit is the exact same thing because those loads are now both running in a 240 volt circuit so you would think the more resistance in a circuit the less current is going to flow but if you increase the pressure to 240 volts you double that voltage the same thing is going to happen so those loads are not going to explode or nothing bad is going to happen to those light bulbs we're just now increasing our voltage but also increasing our resistance so the current will stay the same throughout that circuit now can i fit another color in here to make this even more confusing what happens if we were to say that these are not two amps and two amps what if this is like a super huge you know like 300 watt lamp or something we'll just say that there's 10 amps that are flowing through that load and we'll say that there's two amps flowing through this load this is a lot smaller uh bulb so because we have both of these things again we have the current on this neutral that is in a pushing cycle where we have it on a pulling cycle on the other phase then you're still going to have current that's able to go partially this way and partially this way but the the the proportion of the current in those situations is going to be different so we have more current that's able to travel through this circuit than there is through this circuit so it's actually a subtractive event that happens so if you have 10 amps minus 2 amps you have 8 amps of current so there would be current flowing through here and you would take your multimeter you'd clamp across that and it would read eight amps so in that situation with an imbalance load yes current does always carry the imbalance because there's nothing preventing it there's no like perfectly even wave that's cancelling out this was something as a helper that i was always trying to understand i was just like wait if current's not flowing where is it flowing and it has to flow it has to go if you have a completed circuit there's a load that is turned on there is current moving and carrying that energy through the system somehow and it's not just like like stopping here but somehow still conducting to make the light turn on but there's no current actually flowing you know like a lot of people get confused on that whole thing so let me know what you guys think thank you so much for watching and i will see in the next one [Music] this can't music and video [Music] you

Channel: Electrician U

Views: 210,162

Keywords: electrician, electrical, electricity, dustin stelzer, electrician vlog, construction, residential, electrical courses, electrician courses, electrical class, electrician class, ohm's law, current electricity, daily current affairs, current affairs today, ohm's law practical, current affairs, ohms law, what is current, electrical engineering, amp, ampere, journeyman, potential difference, electrician show, circuit analysis, electronics engineering, electrician job, trade school

Id: 4u83B3lAqmY

Length: 23min 3sec (1383 seconds)

Published: Mon Feb 07 2022