 In this video, we're going to look at a balanced 3-wire circuit. Now, what a 3-wire circuit allows us to do is it allows us to have two different voltages available to us off of one service. Sound familiar? That's how your house runs. You have 120 volts, which basically takes care of your lights and your plugs and your TV and all the fun stuff, and then you have your 240-volt load, which is basically all your heating loads and other things as well. But in a typical house, it's your heating, so you've got your baseboard heaters, you've got your dryer, you've got your range, your oven. So those would be covered under the 240-volt. Now what we'll do here is just to get the points across, I'm going to assign some values to these batteries, and then I'm going to assign some values to these resistors here, and we're going to have a little chat about how this 3-wire circuit works. So let's just pick a nice and easy one. Let's go with 120 volts. So let me just change my pen color here to a nice red, and let's say that that's a 120-volt battery there, and that's a 120-volt battery there. Now I'm using batteries in this instance, but it could be very well AC, and in your house it honestly will be AC, but we'll just go with that for now. And then let's pick some resistive values for the resistors. So I've got, let's go with 10 ohms here, 20 ohms on this one. Let's say 30 ohms for the 240-volt load. I've got 10 ohms on this resistor and 20 ohms on this resistor, which basically balances my load. Now in a 3-wire circuit, like I mentioned, I have two different voltages available. So if I follow through here, starting with my negative, I'm going along the negative line, and I come up through 300 ohms and I go back to my positive, I end up with 240 volts at my 30 ohm resistor. Now what's going to happen on these other loads, these little loads here, the 10 ohms and the 20 ohms, is basically my current's coming through here, and while I have access to this neutral, I don't really need it. Because what's happening here is if I've got two equal loads in series with each other, well, remembering what we learned from Kirchhoff's law is that the voltage is going to split evenly across it. So from this point to this point, yeah, I do have 240, but because this is a balanced load, this is only going to see 120 volts and this is only going to see 120 volts. So this neutral, not required at this instance. Same thing over here, this is 20 ohms, this is 20 ohms. These are both in series with each other. So what's going to end up happening is, again, 240 from there to there, but split in half because these are in series with each other, 120, 120. So what's going to happen to the current along this neutral? Let's find out. Now, let me just change my pen color to a nice blue and I'm going to say, okay, using Kirchhoff's law, I know that if I go 120 volts divided by 10 ohms, I'm going to get 12 amps, 120 volts divided by 20 ohms, I'm going to get 6 amps. So let's write that in there. This is going to be 12 amps and this is going to be 6 amps. Down here, it's the same values, 12 amps and 6 amps and then over here, and this is where sometimes I see some students forgetting things, is that from this point to this point, you only have this one resistor across 240 volts. So we're going to go 240 divided by 30 and we're going to end up with 8 amps. So let's just write that in there with a nice blue. Alright, so we have all our currents figured out. Now what we need to do is figure out what our line currents are going to be, line 1 and down here, line 2. And the way we can do that is looking at these nodes and talking about Kirchhoff's current law, we've talked before about how whatever the current entering the node is, it has to be the current exiting the node. So if we look at this, now we see that current is heading this way. I've got 8 amps flowing here. Let's just use this as an example. 8 amps flowing here to this node. It picks up 6 amps here, so I end up with 14 amps and then it picks up another 12 amps here and I end up with 26 amps. So let's get that written in there, 26 amps. Then let's take a look down at the bottom here. Same idea, as current is coming along here, we have some value of current coming from there and it's dropping off 12, it's dropping off 6 and it's dropping off 8. Coincidentally, that works out to be exactly the same thing, 26 amps. So I have 26 amps on line 1, 26 amps on line 2. Now what that means for our neutral is because they're completely balanced, there is no need for any neutral current to be flowing here. Because what's happening here is if we look along here, this 12 amps gets to this node, it doesn't have to pick up or drop off any current because it ends up being the same here. So 12 amps still maintains 12 amps and goes across here. Same thing here with 6 amps. Comes up to the node, it doesn't have to pick up or drop off any current. So it just stays happy being 6 amps. So you have zero current flowing in the neutral, zero amps. That's kind of a dream when we're trying to get our loads all figured out for our residences or commercial or any industrial drive. You try to balance your loads so that you have a minimal amount of current flowing on the neutral. Because the neutral's job, it provides a reference point and a safety point for the ground. But it is also there to carry the unbalanced current. Now in this video, we focus strictly on a balanced circuit. So that's going to be zero amps flowing through here. But in other videos, we'll talk about an unbalanced current where if these values, these 10 ohms and 20 ohms and 10 ohms and 20 ohms are all different, let's say it's like 10, 5, 35, 15, that's going to throw things all out of whack. And so that changes things. But right now, for as far as we're concerned in this video, everything's balanced, everybody's happy and the neutral has nothing traveling on it.