This episode of the HVAC school podcast is made possible because of generous support from our sponsors, rector seal test, o carrier and Mitsubishi, and one thing that I want to mention quickly about Mitsubishi is that we've dealt Mitsubishi? I guess it's been since about 2009. We started our business in 2005 and I actually drove up to Asheville North Carolina to take a class in order to become a Mitsubishi diamond dealer. And if, since that time, we've sold just thousands of Mitsubishi ductless systems. And we really like how sturdy they are, how they hold up and one thing that's kind of nice and having both rector seal and test.

Oh and Mitsubishi ductless as sponsors of the podcast, is that the three of those brands really converge a lot for us day to day when we're testing and cleaning and installing ductless systems, because we use the rector seal dissolve kit in order to get the evaporator coils. On ductless systems really clean, when we need to do a really thorough cleaning of the unit in place, we can do that with the rector seal dissolve kit for testing Mitsubishi ductless systems. We use the test O 605 eyes, as well as the test of smart probes. When we have to connect to the actual refrigerant lines, we don't want to use a regular gauge manifold and potentially lose even a few ounces of charge.

So we use the test of smart probes to connect and we use the test of six or five eyes to actually verify delivered capacity on the unit and all in all Mitsubishi rector seal and test o have been great partners. If you want to know more about how we do a ductless cleaning, a ductless maintenance, we actually just put up a video just a few days ago, actually last week on our youtube channel. If you go to the hvac school youtube channel, you can find that video. There of us using the rector seal, dissolve kit in order to clean a mitsubishi, ductless and then at the end we use tests.

Oh six, oh five, eyes to verify the system's operation, and i think some people who hear me talk about these products may think. Well. Gosh, you know Ryan just talks about whatever products happen to sponsor his podcast, but as it turns out, these are all things that we used before. There was a sponsorship, so it's kind of cool that we were able to go out to the marketplace.

Build relationships with these manufacturers and then have them become a sponsor of the podcast, and it just shows their commitment to training to the industry that they're willing to actually put their money where their mouth is and support. This free training that you can use, and so that is rector seal test, Oh carrier and Mitsubishi, and now the man who stays humble because he has two teenage sons who always let him know how much smarter they are than him Bryan or yes, oh my um. My oldest son, just turned 16 he's a great kid. He really is he's a hard-working kid.

He works on his own car and all those kind of all those kind of good old timey things that you that you look for in a young man. But but he is, you know, he's still a teenager and he is my son and so as my son, he doesn't. He doesn't think that anything that I do is interesting, except just the other day he he's sitting with me in the car and he says: hey Dad, you know how a scroll compressor works and I'm just kind of looking at him like like seriously. Is this a joke and he wasn't joking apparently been talking to my dad, my dad's, a general contractor and an electrician by trade, and my dad was telling him about scroll compressors.

I guess and now they're how they work on whatever, and so my son proceeds to tell me about oscillating, scrolls and decreasing size, compression chambers and - and I thought it was pretty humorous because of course he he just thinks that I had never heard of that before And that he was educating me on something which you know who knows? Maybe he does know something. I don't know, oh by the way, this is the HVAC school podcast and I am Brian, and this is the podcast that helps you remember some things that you might have forgotten along the way as you're doing your daily daily job and the HVAC, our trade, or It might remind you of a few things that you forgot to know in the first place, and today's podcast is specifically about three-phase single phase and split phase power and some of the differences just kind of setting the baseline of understanding the difference between them. Because there is a lot of misunderstanding out there about, especially about three-phase and really three-phase power is such a simple concept. It really is very simple: it's not not difficult to work on, but some technicians miss a few things along the way, so we're just gon na.

Do a quick brush up episode here, leading up to Christmas 2017 in the new year, so by the way Merry Christmas, that is, that is coming right up, I'm recording today it is Friday the 22nd and lots of Christmas preparation for me and my family. As you know, I have nine kids with number 10 on the way. Actually I don't know if I announced on the podcast at number 10. It's on the way, but number 10 is on the way, which was uh, which was not intended, but we're gon na be thankful to have another baby and then that'll be it after that.

I won't go into the gruesome details of how that ends anyway. Enough about me in my personal life, but needless to say, Christmas is very busy around my house, but I figured hey. I can take a few minutes. Just do a little solo episode on 3-phase power all right.

So, let's start with the basics, and this is the. Why so, why do we have single-phase power, and why do we have three phase power? What's what's the reasons? Well, here's the first thing that that you might want to know, and that is that that first stuff at the power plant, the power plant, the power company, generates three-phase power, that's what they that's, what they generate, and so often, if you look around like a major Highway or something or just not not even a major highway would be at the street, and you look up at the power pole. You'll usually notice three main current-carrying conductors, and then you will have a neutral neutral, slash ground down below it. In most cases again, you know there's different configurations of power poles, but the point is that you have three of these lines and those three lines: each individual one carries a phase of power and that phase of power each phase of power runs at 60 Hertz, which Is 60 cycles per second, which means it starts at zero.

Goes to peak then goes all the way to valley. So when we say we say a positive and they give and positive and negative can even be a confusing thing. But if you ever seen a sine wave, you look at a sine wave, it looks like you know, a hump, a pump that goes up and then a hump that goes down. So it starts like a hill and then it goes down a valley, and then it goes up a hill and a ghost in a valley, that's a sine wave and on a sine wave.

When you look from left to right, if you're reading it like a book that's time so that as the sine wave goes from left to right, that represents time, and so one cycle is one full cycle from zero. All the way to peak positive down past zero. Again down to peak negative and then back up to zero, that's one full cycle! So if you imagine that almost like a circle, it's 360 full degrees, it starts in the center, goes all the way up to the top loops back around and then back to the center again, so it cross. It starts to the center crosses the center, and that Center is zero, zero volts, a potential, and then it ends up back at the center again and that's one full cycle, one full circle, and it really is a circle.

It's just it's just going from positive to negative and, as you know, power is generated in a rotating magnetic field, so think of things in circles and that that helps you to kind of think of how electricity is generated and also how it's used within within Motors And within other other magnetic devices all right, so all of this is nothing new. I feel like I've, given this particular talk a couple times, but it's just important to understand that. So when you think about a single phase of power within three-phase one of those wires, it still abides by. You know there was the same rules: it's 60 Hertz, it's just a Mountain Valley, Mountain Valley, typical typical 60 cycle, 60 Hertz per second circuit, so that that conductor, that that wire, that's running across the main road that you as you're driving by one of those three.

It's it's still cycling at 60 per second and it doesn't matter the voltage. So it can be. You know. Even you know, generally speaking, I think - and I'm not sure of this - I don't I don't know for a fact, but I think it's 7,200 volts is what they use for typical transmission power, Ford's step-down in a residential light, commercial type area.

Obviously, with for the big power lines that run great distances, they can be higher than that, but but your typical, you know ones that run along inside the street. I think are 7,200 volts, typically not that that matters. But but the thing to know is that even even though there's 7,200 volts, potentially the 60 cycles, the 60 Hertz still remains the same. It's still cycling, it's going Mountain Valley, Mountain Valley, 60 times per second, and so that's for each individual wire.

But when you have three of them, then the question becomes: okay, not only what is the cycle rate, but what is the degrees of difference between these different legs? And this is where you tend to lose people, people kind of understand the mountain valley. You know cycle rate of one conductor or one circuit, but then, when you add in these additional circuits and they're not all the same, then it can start to throw you off a little bit. So, let's first before we even get into that also will first just say this: those three conductors that are running alongside of the street, those three phases of power. Those three separate phases are all 120 degrees out of phase okay, we'll just we'll sit we'll set that there and then let's go to a typical house transformer, so a typical regular old at the street house.

Transformer could be up on the pole. It could be down on the ground on a pad. It doesn't matter that transformer takes that high voltage and again, I believe it's generally 7,200 volts and it's and it brings it down to 120 volts. Now it brings it down to 120 volts split-phase and some people will even call it three-wire single-phase.

I think it's a term people will use for it, but we just call it single-phase. We call it single-phase 240, most often, and why is it split face? Well, it's split face because they're taking one leg, so one leg of this again, I'm gon na keep saying 1770 200 volts, I'm not uh, I'm not aligned. I don't, I don't know exactly, but I think that's what it is. 7,200, volts that comes in one leg of that connects to that transformer and then the other side of the primary of that transformer connects back to back to neutral, and so you have these.

You have 7,200 volts of potential, that's running at 60 Hertz, but then what they do is when they wind this transformer. They wind them into separate opposite directions. So you have one set of windings that that winds, one direction, that's one leg of 120 and then you have one that wins the other direction. That's another leg of 120, but because they're wound in opposite directions.

The the sine wave ends up being directly out of phase so 180 degrees out of phase, which means that if you were to look at a typical 240 volts service coming into a house, what we call you know: split phase power or single phase 240 or whatever. You have these two legs that are directly opposite from each other in sine wave, so when the one is at the peak of its hill, the other is down at the bottom of its valley, they're exactly opposite, and then the center is neutral. So if you can kind of imagine this, the secondary of this transformer has three points on it. It has a winding on the left.

It has a winding on the right and then right in the center is where that neutral tap is in the center of that transformer and their wound opposite directions. So that way, the induced frequency is opposite for the two of them, and that's that's what we call it split phase. That's where the term split phase comes from because you're taking one phase of power and you're splitting it two different directions to create these opposing phases of power. So now in a typical house, you will have 120 volts from one leg to neutral and you'll have 120 volts from the other leg to neutral, but they're opposite of each other.

So that means between both of them. You will have 240 volts and they're constantly changing. So it's not like one spot. Even one is a negative.

I get a lot of technicians who asked me this: it's not they're constantly, switching from positive, negative, positive, negative, but they're always opposite of each other. Now until they hit that center point. So there's one point: in the center of both a 120 volt circuits are just a single you know, so one half of the split phase or in the 240 volt, where you have both halves of the split phase right when they both intersect in the middle with Neutral, where it goes completely off so whenever they, whenever those sine waves intersect, is completely completely off, and so it's not it's not a perfect setup, because, no matter whether you're using 120 or no matter whether you're using utilizing 240, you still have power. That not only is fluctuating because it's alternating current, but it's also going completely to zero potential when when they intersect in the in the middle there.

So - and that happens you know so it happens at the beginning of each cycle, the middle of each cycle and the end of each cycle, because you think into that whole circle. Again, you know if you, if you're thinking of like a you, know, if you're drawing a circle with a pencil, and you start in the middle of the circle and you go up and around and then you hit the middle of the circle again, that's completely off And then you go down and back up again and you hit the middle of the circle and now that's completely off again, you think of like the horizontal plane, like you have a line. That's splitting that circle and that's again, I'm overstating this, but that's neutral. That's neutral or what we'll call you know we connect neutral to equipment ground.

We connect it to an earthing, an earth ground as well, and that that becomes that kind of off point. And so we just have this less than optimal power, where it's just going off a lot. I mean now it's going very fast. So it's it's! You know just these instantaneous moments where it does go off, but it still is going off and that's because we're only using one leg of three-phase power and we're splitting it in order to create 240 okay, so you got that in your head.

So now, let's talk about three-phase power. Let's pick up what I left you with there three-phase power is a hundred and twenty degrees. The phases are 120 degrees out of phase so that on the face of it, it's like what does that mean? 120 degrees. Well, just think of it very simply because a lot of people struggle with remembering this, even I struggle sometimes of this, is like how many, how many degrees, what does that have to do just think of a circle? A circle has sixty degrees right.

So when you, you know, when you go when you spin around in a complete circle, that's spinning around three six 360 degrees. If you just turn around halfway so you're facing one direction, you turn around the other direction, that's 180 degrees, so 180 degrees is opposite. 360 degrees is all the way around when you have three phases of power. There are a hundred and twenty degrees out of phase easy to see how that is just take 360 and divided by three 360 divided by three equals 120.

So it's just you're taking you're, taking the full circle and you're taking a third of it, and that third is 120 degrees, and it doesn't, if you know, for most of our for most of what we do. It's not important that you fully understand all of the math of this, but it's just a good way to it's a good way to kind of get your head around it. If you're thinking of a circle, think of each one making up a third. So imagine you have a pie and you've got the pie and it's cut into thirds and each one of those thirds represents one of the phases.

And so what happens in that case is that, instead of having a point in that cycle, where you have two that are completely off that have hit the zero point in three phase to power, you only have one that's at complete off at any given point, which Means that it's a much more, it's just a much more logical use of energy. So the way I often describe it is think of spinning a pinwheel okay. If you let's say you have to spin a pinwheel and you can only use your hands two hands and you can only basically slap it on the sides. That's all you're allowed to do well, just try to get a pinwheel spinning by just smacking it on the sides without being able to put any like English on it, and it actually could it's spinning.

It's not gon na work. It's not gon na work efficiently. At all, and if you think of split-phase power, that's sort of what it's like, it's like on off on off on off on off with your with your hands back and forth, opposing forces and that's not a good way to turn things. It's not a good way to run motors and in our business, that's you know.

The highest current carrying devices are generally motors right, compressors and blower motors, and that sort of thing so so we want to be able to run motors efficiently split face power, 240 volt power that we get in a typical house. Just isn't great at that and that's what we have to add in capacitors both you know either to get it started with a start, capacitor or a run capacitor. That's always sitting there helping or both something do you know a start capacitor to get it started and then a run capacitor to continue running it and that's what we call an auxilary winding, a secondary winding, a start winding is what we'll often call it, and so, If you think of, if you think of what we do with single split phase power, split single phase power, is it's like taking two hands on a pinwheel and then having a little third hand, they just kind of help spin, it just a little tiny third hand. Well, if you make a three-phase power, spinning a pinwheel, it's like having two hands and an angle opposed to each other at the bottom and then one on top and there and they're just perfectly timed to spin that wheel and so as they hit it.

They're perfectly they're perfectly spinning that wheel and it's a - I always use this metaphor and I get made fun of for it because I mean like yeah talking about pinwheels here, and this is a professional podcast about air conditioning refrigeration. But but it's a good picture. If you imagine three hands that are set up perfectly to spin a pinwheel, that's kind of the advantage of three-phase power, and so you in three-phase power you always have two phases fully engaged where, as I say, fully engage the two phases that are currently active in The circuit at all times, even when that third phase is completely off when it's hitting that center point and so three-phase power. When you have three-phase power, you don't need capacitors, so you can.

I mean the capacitors too, are still used, sometimes in three-phase systems, but it's not in the traditional way that we use them to start and run motors you can, you can take a you know, a motor, a typical. You know, kind of middle sized. You know 5-ton 10-ton, compressor and just connect three-phase power straight to it, and it can just run just on that three-phase power. Now you have part start starters and all this kinda stuff and that's it that's a different thing.

But but generally speaking, you don't need anything special to run a three-phase motor. You can just connect the power to it as long as the our distribution system can handle V and rush amps and all that kind of stuff. But but you can really just connect three-phase power to a three-phase motor and it will just run and it will and it will run the same direction every time unless you've switched two phases. And so this is the one thing like if you're taking an eighth exam or you know a test, this is a question that a lot will ask.

You know how do you change the direction on a three-phase motor? Well, the answer is you just switch any two phases and that changes the direction of a three-phase motor, which is actually very important. One of the most important things to consider on a three-phase system is making sure that you keep the phases in the proper sequence. So in the US generally speaking, phase one is black phase. Two is red phase, three is blue, but sometimes it'll use, brown and yellow and other other.

You know you could potentially see anything, but generally it's black red and blue, and you have to make sure that that phase sequence is in the right sequence, all the way down the line. If it gets swapped, then you could have compressors that run backwards, blowers and run backwards, cadets for fans that run backwards, any three-phase motors where the phasing is reversed. They can they can run backwards and - and that can be a problem in some cases. So so that comes into that comes into play there, but you don't have to have this little tiny third hand that we create with a capacitor like we like.

We do with this typical split phase single phase 240 system, so so three-phase power is actually very simple. It's it's really designed for motors. It does a great job with motors, but we have this. We have this issue still most buildings.

They may have a lot of big motors. Let's say it's a factory or something okay. So it's got a lot of big motors that do really well with high-voltage three-phase power. Well, they weren't great, but you still need some method of running a computer or at these typical appliances that run off of 120 volts, and so we have to, in some cases, use only single phases.

Now remember that single phase, if you take it from the power company and you drop it down from 7,200 volts down to 120 volts - that single phase in relationship to neutral is generally going to be exactly the same as it would be in a single phase application. You have a neutral, that's tapped in the center, and then you have the phase and that's what we call a Wye configuration so in a Wye configuration instead of you having in a split phase. You've got two windings. Imagine again in your head here you get two windings.

One goes off to the right. One goes off to the left and the center is neutral. You have 120 on both sides. There are 240 to each other 120 to the center.

Okay, that's what you have in your typical house that split phase single-phase power, but a three-phase application three-phase. Why imagine a center point? That center point is what we're gon na start, and that is your neutral. And then you have a winding that goes up and you have two that go and angles in the bottom and it kind of makes a star like a like a yeah three, a three-legged star and that's what we call a y configure transformer and that's the most Common, it's the most common type of transformer that we see in commercial, most commercial applications, but we do also see something called Delta which I'll talk about here in a second but but generally speaking, we're gon na see this this Y configuration and what that means is, Is that each leg of power is going to have 120 volts tuned to neutral, and so when you wire something with one leg, you know l1, l2 or l3 of power. It goes through the whatever outlet or you know, computer or the space heater or fan or whatever it is light, and it comes out the other side and goes to neutral, and it's gon na have a hundred twenty volts applied.

Alright, but here comes the here. Comes the thing that confuses a lot of people, because, instead of it being two hundred and forty volts between two legs of power, because that's what we're used to we're used to split face power where there, when one is at peak the other, is at valley. They're. Completely opposed to one another, 180 degrees opposed to one another and actually - and this is something that it just bears saying - I said this in a previous podcast, but but it but that isn't the peak either.

So when we're reading 120 volts to ground, it's not actually just 120 volts, it's 120 volts RMS, which means root-mean-square. When you have a meter that says true RMS meter, what that means is it's able to actually measure and come up with what the equivalent potential difference would be if it was DC. So when we are taking alternating current, it's constantly going up to a peak down through the center, that's off and then down to a valley, and so when reading 120 volts it's actually higher than that. That's the peak, but we're not measuring peak we're.

Measuring what the effective comparison is between alternating current direct current, so your meter does the math RMS means root, mean square, it's a mathematic equation and it comes up with what is the effective potential of this particular circuit. So, let's I digress, but the point is: is that we'll read in a three-phase building you read the same as you will in a single-phase building you'll read under 120 volt plugs and 120 volt appliances. You will read a hundred 20 volts somewhere around 120 volts. I just did it today in my building, my 3-phase building and I measured 122 volts, so you'd think that between phases you would read 244 volts right 122 volts on a 22 volts.

Their opposite so would read 244 on single-phase. What we call split phase. You would be correct, but on a three-phase system you would not be correct in most cases and then because in most cases we use a Wye configure transformer, which means that you have phases that are a hundred and twenty degrees at a phase. Instead of being a hundred and eighty degrees out of phase, and so because they're not a hundred and eighty degrees out of phase these two phases of power, they're not peaking a value at the same time, which means at any given point when you measure there's not As much potential difference between them, which is where we come up with this this term three-phase 208, therefore that for three-phase 208 and most appliances, when they're, three-phase they're 208, so most systems most pieces of equipment when they're three-phase they can function on three-phase 208 or in Some cases both you know you there's there's different types of things: I'm not gon na go into all that, but but there you see that commonly write, three-phase 208 and three-phase 208 is a.

Why configured three-phase system of the most common voltage that we see in the US? But just because it's three-phase 208 doesn't mean that the individual legs are less than 120 there's still 120. They just don't add up to 240 because instead of the legs of power being 180 degrees out of phase top and bottom of the circle, they're only 120 degrees out of phase. So if you think of the circle being cut into thirds, so the distance isn't as great between them. Therefore, the potential isn't as great between the two different legs and that's where we get that term.

So you will also hear about three-phase 240, okay, and sometimes that's just a mistake, because sometimes people think I will it's in 240. So these three phase is 240, but but it there is an actual three-phase 240 and that's when the transformer is configured in a delta orientation and so they'll intentionally configure it in a delta and a delta is a triangle. So, instead of it being a Wye with a point in the middle and then the three little arms going and 120 degrees different from each other opposed to each other, that's the why some people will call it a star. You have the Delta and the Delta.

Is a triangle and in the Delta? Really what you need to know is that I'm not going to go because it gets a little more complicated now, but but here's the main thing you need to know on a Delta configured system. You're gon na have 240 volts between phases. You're gon na have 120 volts to ground on each leg. So that's nice! You get the best of both worlds.

You get 240 volts between phases and you get a hundred twenty volts to ground, but that hundred twenty volts to ground is on only two of the legs, and this is what we could. They call a high leg Delta. This is the most common one that you'll see of a Delta system. It's called a high leg Delta, so two of the legs will have 120 volts to ground, but for heaven's sake, be careful because there is one of those three phases is what's known as the high leg or the wild leg.

This is the the term high. I know high leg Delta. One of these legs is high to ground because, if you imagine so imagine, you're looking at a triangle - and the three points of the triangle represents the three legs of power, so l1, l2 and l3, okay and at the bottom center of that triangle. So if you mention the the flat part at the bottom of the triangle in the center of that, that's where the neutral is tapped, so between the B leg, which the B leg is the one at the top of the Delta, if you're looking at it, the Way, it's typically drawn between the B leg and neutral.

You will read 208 volts, so the B leg in neutral ritu, oh eight, and when I say you will read 208 and I can vary a little bit but you're gon na read around there 280 volts and again you're talking about a leg of power to neutral 208 now imagine if you wired up something wrong so that instead of going between the a and C leg and neutral, but instead you did it between the B leg and neutral, you would burn it up. Basically, when it comes down to, and so many a technician have burned up, vacuum pumps using Widowmaker cords by connecting to the high leg and a high light Delta system. And so whenever you are working on a three-phase system and you notice that between phases, you have 240 volts or thereabout. That's probably what you're dealing with you're, probably working on a high leg Delta system.

So just keep that in mind. But if you want to know a B and C, you know just imagine imagine again you're looking at the triangle and so the left. You just read things like a book. You know generally, that's how you do it, and so the the far left is your a phase at the bottom bottom left of the triangle and then the top of the triangle.

If your B phase and then the bottom right is the C phase, and so it's that B phase that you got to watch out for, but again you never just never trust how things are marked, always use. Your meter always check yourself and when you check in between the leg of power and ground - and you see higher voltage and you should in that 208 range - you know that you're looking at the at the high leg, so we've covered single-phase power and with single-phase power. We know that generally, you have to you know, especially for you know typical motors and we're not talking about ECM motors and shaded. Pole motors are an exception, but for most motors you have to have some form of start assistance, something to help the thing start and usually that's a capacitor or some sort of there's start capacitor and a run capacitor or just a run, capacitor to help get a Motor started in typical split phase power.

That's the you know: 120 240 volt power that we see coming into our our nura homes. That are a hundred eighty degrees out of phase. And then you have a Y system, that's what we call 208 three-phase and that Y system is and it doesn't have to. So let me just back up here real quick just because something is, why doesn't mean it has to be 208.

They, you know, have the 480 volt 208 systems, and these are almost always industrial or very large commercial type sites where they'll have, in some cases, they'll even have mix so you'll have some panels that have 480 in them and then you'll have others that have the Typical 208, but but these are generally Y systems, they do make 40 volt Delta, but but generally most cases when you're doing with 4 it's a Y system and in a 40 volt why you have 480 volts between lake's of power and then 277 from leg to Neutral and so sometimes they'll use - you know any like again in big industrial facility, still use the 277 for lighting and then they'll use the 480 to drive their their equipment, and so the 277 is still only using one leg of power. So technically it would technically be single-phase 277 lighting and just using one lake of power. But again, whenever you use a single leg of a three-phase system, you want to make sure that you balance out the current of the lake so that you don't have one leg that is much higher current than another. It helps balance out the loads and bounce out.

What's being carried on neutral, if that's a whole other consideration that generally you know, electricians are gon na make, but but that's you know, you generally want to have a building, that's mostly three-phase loads or mostly single-phase loads. So that way, you can get everything well balanced out. When you have a lot of mixed use within a power distribution system, it makes balancing of the loads a little bit more challenging, especially when the loads are variable. You know when they change a lot from in different times a day or you know, different processes are in place.

So obviously there are exceptions to this there's exceptions to this globally. I know there's a lot of you who listen who are not in the US. I'm not going to go over all the different global exceptions and, and obviously there can be circumstances where different industrial processes use even higher voltages. Or you know you can work with step-up transformers that you know just step-up voltage is much higher than that, but but when we're talking about single phase versus three-phase those are really the things that you need to know.

You've got single phase, which is, we know, split phase which we deal with in residential environments, where you have a hundred twenty volts per leg. It splits two different legs of 120 that are directly opposed. You have 208 three-phase, which is a Wye system when we say 208, that's 208 volts between legs, but it's still 120 volts between each leg and ground. We have a delta high leg Delta, which you'll see a lot which is 240 volts between phases.

But then you get a watch out and two of them two of those legs. Both the a and C phases are 120 volts to neutral, but are on the on. The B phase are 200 208 volts to neutral, and then you have 480 volt Y systems are more common and you have Delta systems in some cases in 480 that have no neutral whatsoever. They're, just a you know, there's no neutral at all, which creates a whole other set of challenges and confusion.

But those are the typical, the typical ones that you're gon na see and obviously the the environment that you're in is going to help dictate a I mean. Can there be three-phase run to a house? Is it possible sure? Are there some places where, where that happens, yes, there are, is it common? No, it's not so you're, not gon na generally expect to see three-phase on a house. If you're dealing with the commercial structure, a you know, there's commonly commercial structures that are only single-phase. Usually you know storefront type places that they don't have a lot of equipment.

You will find them that are single-phase, but in many cases you will find - and this is kind of what I'm getting at here - you will find commercial play spaces that have three-phase power available. So there's a three-phase panel, three different bus bars three different legs of power, but they still use single-phase equipment, and so this is the kind of the thing that I want to leave you with, because the rest of the stuff is fairly it's. It's not such you're gon na apply all the time other than the whole like and he's. Switching any two legs will reverse the rotation of motor, so phase rotation.

That's something that a technician needs to know in our field, but when it comes to putting in single-phase equipment on three-phase power, that's something you do need to know, because that is not ideal. Just know this, then, when you take a typical single-phase unit, so you take a residential type unit and you put it on a building that has three-phase 208 that units only gon na get 208 volts of power to it. I mean, obviously it's it's often a lot. A little bit higher than that not a lot a little bit higher than that, so like 212 213, but it's still not the full, the full rated residential voltage.

Now these units are rated for 208 240 in most cases, so they can run on 208, but recognize that you are reducing the capacity and the efficiency of the unit by running it on a decreased voltage. So it's not going to produce that full capacity. Most manufacturers will give you a a table or they'll, give you an adjustment for 208 so that you can see how it's going to affect the capacity, but just know that you put a five ton unit in a building that has 208 volt power. 208 three-phase you're.

Only using those two legs, instead of actually putting in three-phase equipment it is gon na, take a hit and the efficiency and in the capacity versus its three-phase counterpart. So, whenever possible, if you're retrofitting equipment and a new three-phase breaker new, three-phase WIPP can be brought into that piece of equipment that is advantageous you're, going to provide better efficiency for the customer and better reliability. I mean you know: what's the thing that fails most often on single-phase equipment. Now I know you all just said x13 motor modules, no, not 13 motor modules.

Those did fail in the past, but but the capacitors fasteners are what fail most often right. It's the most common fail item on a single-phase piece of equipment, and so, when you put in three-phase you eliminate the capacitor, and so you really have a much better operating system when you put in three-phase. If you have that option - and so obviously you you it's going to take some upgrades, you have to have a new breaker and a new whip at the minimum. But it's it's better also from the standpoint of balancing the loads, because if you have single-phase equipment, that's on a three-phase panel now you're gon na have to try to balance that all out.

Whereas, if you're using three-phase equipment on that panel, then it's going to naturally be balanced between those three phases. Now my one of my sales to have asked me this. Just the other day said you know. Well, this one building had a single-phase air handler and a three-phase condenser is that okay? Well, when you're talking about five tons or less that's very common, I mean that you really don't see three-phase fan, coils or furnaces that are five tons and under that's not common.

But you can find three fights condensers. The reason for that is is that the load on a furnace or fan coil is significantly lower than it is in the condensing unit. Because of the compressor and the compressor is the is the component that most benefits in an air conditioning system from three-phase power, because when you're talking about resistive loads, like lighting or like in heat strips things like that, those don't benefit at all those don't. Those are only gon na use two legs of power anyway, there's no purpose for three-phase power, three phase power really is there and it's beneficial for running motors? That's that's what it does well, and so you having three-phase power when you're running resistive loads, doesn't even make any sense, and so, when you're talking about an air handler, you don't have a lot of load there.

At that point, it doesn't make as much sense to run a three-phase power to it, because three-phase motors also they're just less ubiquitous, so less common. And so when you have something that's less common, they tend to be a little more expensive. Even though the truth is that you know winding a three-phase motor isn't really any more difficult, I'm sure than doing a single-phase there's just not as they're, not as common. So so that's why you will often see in the five tons and under you'll, find that there are condensing units that are three-phase but air handlers that are not, but whenever possible, here's the point: here's the message here whenever possible, if you have three-phase use three-phase, don't Just in and I cuz I've seen people do this, where it's three-phase power, they didn't notice it they order a single-phase unit and they're like a she will just put in the three bullets, use two legs of the power.

Well, that I wouldn't do that! It's not it's not a good practice and also keep in mind, because I had someone asked me this: can you just connect two legs of power and leave in a three-phase breaker? No, I wouldn't do that. That's not a it's, not a good practice to leave a leg just sitting there, especially in a common trip device. It's gon na be less likely to trip when it should. So.

If you're gon na replace something three phase with single-phase first well, I don't recommend that. But if you're gon na do it, then you need to put in the proper breaker. So if it's a three-phase system, it needs to have the proper breaker and if it's single-phase, it needs to have a proper breaker, and for that and again, I'm not telling you to do electrical work. If you are not licensed to do that, work in your area in some areas, you're able to do certain electrical things with the HVAC contractors license, but that is up to your municipality, your country.

You got to follow your own codes and regulations and my company we are both licensed electricians and licensed Air Conditioning Contractors. So I you know we're doing this stuff and that's why I talk about it as if I'm gon na do it and I'm not saying that you'll necessarily have to do it. But you have to have enough knowledge to know what's what what the options are, because, if you don't know, you're, not necessarily gon na bring in an electrician into the equation, even if you need to sometimes and so understanding how this all works is gon na be Helpful so message here is three phase: power for operating motors is better, so it's just better, and so, if you have that option, use that and recognize what the limitations are of each are, and also for a gosh sake. If you notice 240 volts between legs on a three-phase system, three-phase structure then make sure to test for that wild leg.

If you're ever going to use something that goes in between a leg and neutral to make sure it's not that evil high leg B phase, that's gon na blow up your vacuum pump or your shopback or whatever you're running so hopefully you found that helpful. Hopefully, you're gon na have a very Merry Christmas and, while you're at it, while you're, while you're here on the interwebs or listening to podcasts on your phone, if you wouldn't mind going to blue-collar roots comm and looking at some of the other podcasts that there are There I would greatly appreciate it if you would do that, there's a lot of really good content. I'm especially excited right now, I'm excited about all the podcasts, but especially excited right now about service business, mastery, the service business, mastery podcast. So if you are an owner of a business, a manager of a business or you want to be an owner of a business or a manager of a business, I would suggest that you could listen to the service business master podcast with tersh Church is doing something Pretty crazy he's he's actually selling a business and simultaneously starting a new one, all at once and he's documenting that whole process.

Very honestly, so there's really really good. It's like you, get to take a look at the birth of a business right now and it's pretty cool it's. It sounds when I say it. It sounds like.

Maybe this is contrived, maybe they're making it up, but no really he's just recording a lot of these early stage conversations with his with his new business partner and his wife and he's just going working through a lot of the stuff. So I think it's pretty cool. So that's the service business mastery podcast with tersh. Thank you, as always to all of our great sponsors.

If you haven't had a chance to look at Mitsubishi ductless systems, I'm gon na suggest that you go check out their website at Mitsubishi, comfort, calm, that's Mitsubishi, comfort, comm and see what they've got going on. We've been installing a lot of their ceiling cassette units they make these nice small ceiling cassettes. Now we've been installing these in Florida rooms which are kind of like LAN eyes or like outside. You know enclosed porches and a couple retirement communities, and we've really enjoyed installing these in comparison to some of the difficulties that you can have using wall mounted units when you have a lot of windows and pumps and those sorts of things.

So this gives some a really nice option and it's very it a very attractive, looking ceiling cassette. So if you haven't seen those yet, I would suggest that you go check out Mitsubishi. Another reminder I'm going to be at the a HR conference, the HR conference, if you, if you track on the car, if you're gon na be there on Tuesday, so Tuesday is the second day of the conference, I'm going to be at the rector seal booth at 2 p.m. so you can go meet me at the rector steel booth at 2 p.m.

and see me demonstrate the prophit flaring tool and the prophets wedging tool. There's gon na be a giveaway you can enter to to win. You can grill me with your questions and try to prove that you know more than me, which isn't much work to do and most of all, just hang out. So it'll be a fun time if you're gon na be at HR, go ahead and look me up if you want to meet up with me, and you don't see me there at the rector steel booth, you can always email me, brian at hvac, our school comm And as always, if you can visit hvac our school comm and see all of our daily tech tips and all those things, it's great content that you can share with your friends and the biz.

I don't know if you heard, but Santa Claus has actually gone through depression. I mean depression is a serious thing, but he has found a lot of help. He's been he's been reading a lot lately he's been reading. Elf Help books merry Christmas to all of you.

We will see you next week on the HVAC school podcast.