Oh right, all right all right with another all right. On top, it's a good measure, howdy folks, how's everybody doing we'll go ahead and take down the old epic music. You know you can have a little too much epic in your life you're already participating in this epic livestream. So you know a little a little too much epic might affect you negatively hasn't been tested against kovat 19, but you never know so.

I can see here. I can see your chat over here so feel free to to chat it up. If you see my eyes, look this way, I'm looking at your chat. If you see my eyes looking this way, I'm looking straight at you and I can see right into your heart and I can see what's in there, I can see what some of you are thinking and you need to work on that you need to.

I don't know, maybe join a Bible study or something I'm not sure, but alright, so we're gon na talk about some some more myths. It's myth time myth busting time, and I was glad this one came up. This one showed up on Facebook. I was planning to actually bring up the the poll that John Oakes originally posted, that showed how how much controversy there was.

So this truly is a controversy, because a lot of people got the wrong answer. So hey it's a good opportunity right. If something to talk about, but I figured I wouldn't bring it up because I don't want to - I don't want to embarrass anybody. It's a it's an easy mistake to make.

It's a mistake that I that I did make and I will share that story with you. Posthaste, I literally just ate supper. I had spaghetti. I ate cooked baby carrots in about three minutes, so I set up the stream.

I walked into the living room and I ate my supper and I don't know about you. I don't know how your day's going, but let me just share quickly a little bit about my day, I'm where I've been working on a few videos and some other things, kalos related stuff and just nothing went particularly smoothly today, not a big deal, you know, I'm Not complaining, but just nothing went particularly smoothly and don't know if you forehead days like that, and so this is what you're actually witnessing here right now is my attempt at redeeming the day by finishing strong, with a with a video that, hopefully you enjoy. So hopefully we can have a good conversation, so here we go so the questions on the table are, if you change volts, what happens that says, there's a little joke. You know what what happens.

I'm funny and then do motors work different than heat trips, so we're gon na start with heat strips and then you know, resistive loads, resistive type loads and then we're gon na go into motors that are inductive loads and there is a difference. We'll talk about it, but it's important to understand that we have some additional variables at it in and when a lot of things are taught they're taught on resistive loads, like a light bulb or a heater, or something like that. That creates a light and or heat, not magnetism. When something creates magnetism, we call it an inductive load in the resistor that was weird and the resistance that shows up in an inductive load is called inductive reactance versus just straight resistance.

When you take those two and you put them together into a big pot and you mix them up, that's what we call impedance and it's not a term that we use very often in the trade, but you can measure impedance, which is total ohms or total resistance. Okay, so that's what we're driving at, but one of the things that drives me, nuts, I'm gon na I'll, lay it right out there. One of the things that drives me crazy is when people say well just look at homes. Loams law explains it not really.

I mean you can know how to do the math of Ohm's law. You can know Ohm's law and not actually understand how to apply it in real life and what is more important? Is it more important to know Ohm's law equals I times R, or is it more important to understand what that means in real life for a technician, and I would argue for a technician somebody who's out there fixing stuff - that's probably more important to know how that Applies in real life, so here we go we'll start really basic. When the question got asked about what happens, if you decrease the voltage on a five kilowatt electric heater, what happens to the amperage? I immediately thought of this data tag as well as my mistake, something that I did out in the field that related directly to electric heater. So heat strips are fun because heat strips are just resistive heaters and they actually stay pretty flat on their resistance to and we'll talk about what that means, but they they stay pretty flat.

They don't change the resistance too terribly much as they heat up. So you don't see them, you know drawing one resistance and then drawing a different resistance, as they heat up at least not significantly, so he trips are a good example of this and you look at any dated tag on any heat strip. Somebody mentioned that I'm looking extra boss baby today, yeah I, my kids, my kids watch boss, baby and just laugh the whole time saying that. That's me for many different reasons, not just the way.

I look, but also my other characteristics which I'll take. You know I'll accept that anyway, so you look at this chart here at 240 volts, it's 9,000 watts at 230, volts it's less than that, and we can figure out what that is pretty easy. I actually didn't do the math, but if one of you want to go ahead and multiply 230 times, 35 point nine and come up with the actual wattage. You can do that for me in chat, that's just 230 times thirty, five point nine and then 208.

When you decrease the voltage even lower, the amperage further decreases so now to see what the wattage is of this heat strip at 208. You take 208 and you multiply that times, thirty-two point five and that will tell you what the wattage is there. But the point is: is that when you decrease the voltage, you decrease both the amps and the Watts, and so the reason why you get confused is because you take Watts law and you assume that the Watts stay fixed and the Watts don't stay fixed when you Decrease the voltage, the Watts change, and so you have a moving target, and so the question is what really stays constant in a resistive load? Well, on the face of it, it would seem like the resistance stays constant and, in this case, with the heat strip, the resistance is what stays pretty constant, and so, in order to really calculate what's going to happen, when you change the voltage, you have to start With Ohm's law, so you have to start by multiplying your resistance. It's e voltage equals amps times ohms.

So you have to start by like with your resistance and then do the math and we'll do that as we go to the next slide. I don't wan na get. I keep wanting to get ahead of myself so anyway, but let me tell you the story about my mistake and I've shared this on the podcast before, but I don't think I have in a video. This is a heat stripper II, restring kit, that's right behind my head here.

Let me remove my fat head so that way you can see it. This is a heat strip, restring kit and we used to carry these on our trucks. When I was a lad II, a young technician, this probably would have been 2001. Something like that, and I was out it was a very cold winter in Florida, which does happen on occasion, and I was out working on a packaged unit.

It was a ground-level package unit and I had one of these restring kits and I was trying to figure it out. I'd never actually done it before, and so I was trying to figure it out on the insulators and all that well as it got towards the end, and I was trying to make my termination, I just I kind of bent it at a weird angle and I Broke off a piece of the restraint kit and I thought well I'll just figure it out, you know all I'll remake a connection I'll just cut that piece off and all and I'll make a new connection. I thought! Well, you know cutting a piece off of this restraint. Kit, certainly isn't going to hurt anything it just may you know, may make a little less heat made sense to me.

It's got a little bit of the heat strip off it'll, make less heat, draw less amperage right. That seemed to make sense to me. Well, that's not what happened by cutting a little bit off of it. What you're doing is you're reducing the resistance by reducing the resistance you increase the current if the voltage stays fixed, so pretty simple right now: that's that that is really the ramifications of Ohm's law and we'll get more into that.

But if you reduce resistance, you increase amperage. If you increase resistance, you decrease amperage. That is absolutely always true, and that is absolutely how it works. The challenge just is, is that in many cases you can't omit out and then apply current through it and have it continue to still behave in the same way and there's several different reasons why that is okay, so well, let's go ahead and end the myth, though, We'll just get that out of the way before we go too long in this video and just say: myth busted, when decrease voltage on a resistive load.

Absolutely what happens is, is you decrease wattage and you decrease amperage decrease voltage, you decrease wattage and you decrease amperage. That's Watts law and Ohm's law, because the thing in that equation that's staying the same is the resistance and then the voltage is going to be fixed and you revolt. Your input voltage isn't going to fluctuate at least it shouldn't, and so that's where you start. You start with those two variables and then you build your way out see if you have any questions so far, all right there we go Joe says I must have cut more than just a little bit Joe.

I don't remember okay, it was years ago and now you're gon na judge my story. It's a true story. I'm not gon na be ashamed of my story and yes, it drew high amps and the thing started glowing. Okay, maybe I cut a lot off it's possible.

I'm not the brightest boy in from Groveland who was ever born, I'm sure all right. So let's take a look here at at something interesting. So we take a heat strip and we're just we're just gon na further reprove. This we take a heat strip.

I put it on a DC regulated power supply because AC or DC it makes no difference in how a resistive load functions, because it doesn't make any use of that by the time you do the true RMS. So you actually look at true root-mean-square. What that actually is for alternating current and you compare that to direct current. It's gon na function the same 24 volts AC through RMS, as it is 24 volts DC and a resistive load.

So if we drop the current all the way that, like we did here to 24 volts, this particular heat strip - and I don't even know what this one is - it's probably a 5k or whatever it's all the way down at 1.5 amps. So we've proven at this point: when you drop voltage on a heat strip, you decrease the amperage. That's all I was trying to establish they're not trying to get too complicated all right. So one thing again that people always say is it's just Ohm's law, just memorize Ohm's law, yeah! That's all you got to do memorize, Ohm's law.

I would suggest that you stop saying Ohm's law unless you know specifically what you're solving. For I mean this you've got. They got the V over I times R, that's one way of doing it. V divided by I equals R, so you solve for whatever you know, you cover one and that's the one you're solving for.

So if I'm I'm trying to cover it, of course, you can't see me covering it here with my finger. Let's see if I can reach up here and cover it now. My finger doesn't quite make it here, but if I cover for R, then I divide volts times amps and that equals resistance so on and so forth. Right and that's the basic philosophy.

If we increase voltage voltages the force, then we're gon na get more amperage. If everything else stays the same, if we increase ohms, that's the that's the resistance against the force and we don't change anything else. Then our amperage is going to be lower. If we increase so the increased resistance, amperage will be low or decreased resistance.

Amperage will be higher okay. The reason why so many people get confused with that increased decrease of resistance thing is that in our minds, I think we imagine that if there is more physical resistance, we're thinking about motors here, there's more physical resistance to the motion of a motor shaft or to Something moving that physical resistance equals electrical resistance and it does not the more physical resistance you have against a motor moving. So you have a locked compressor, more physical resistance, the less electrical resistance you have in impedance and we'll get into why that is it's a whole inductive reactive, inductive, reactance thing. So the on one hand we have to you have to know what you're solving for, if the other stay the same, but in real life, when you change one, you also generally change the others, which is why this kind of gets complicated.

When we do it really basic math using a you know, direct current power supply, so we don't have to. We don't have to factor in anything on the alternating current side. I don't think about power factor and then, when we're using resistive loads that make some math a lot easier. But even then it gets a little weird - and I have a article about this - that I shared a while ago that Ohm's law ain't simple in real life.

Even with something as simple as a light bulb, so if you measure the resistance across the light bulb, you take, I measure the ohms across the light bulb. You would think that that light bulb would actually have a lot more resistance than it does, but the reality is is that once it actually starts to heat up, I'm sorry a lot more current than it does. Once that light bulb starts to heat up, the resistance begins to increase, and that is a property of many metals. But tungsten is one of the metals that's in a filament on the light bulb, so even with something as simple as a light bulb using a direct current power supply.

Even then, you can't just work Ohm's law, because you could only do it if the light bulb was already hot and how are you gon na measure, the ohms on a light bulb, that's already lit, and the answer is the way you measure the ohms is by Working backwards by taking the voltage in the amps, and then you calculate the ohms so again, if you want to do the math on this, you can, but generally it ends up being about 10 times, meaning that it's about ten times more real resistance shows up. Once you heat up that bulb, then, when the bulb is cold, so even with what we would probably consider the most simple electrical circuit in the world, one that we've got right here with a light bulb and a DC power supply. Even then, if you look carefully at the box, it does line up exactly with the box using the DC regulated power supply. But if you try to work Ohm's law, it doesn't make sense because you think to yourself well, I've measured the Ohm's and it's the math.

Isn't working well, the math is not broken. It's just that. The only way to do the math is in real life. Eric Melanie says, oh good, I was getting worried.

You know what Eric oh man, all right. So next thing is inductive loads are really tricky. So here's one I pulled up this particular compressor and the Copeland mobile app and I looked at the winding resistances, so take a look at the start and run winding resistances on this motor and if you take a look at that run, winding resistance because run is The winding and single-phase that's connected across the line, so between l1 and l2. Your start winding is connected in between one leg and a capacitor, so that capacitor acts as a limiter.

But if you take that point four six and you work Ohm's law with that at a 240 volt power supply that would equal, something, like I think, would be 580. That would be about 580 amps that that compressor would draw if it was just based on the resistance of that winding, in fact a lot of metres. If you were to connect to this compressor with a lot of meters, it would say that it was shorted like it would just go to 0 dead short across the windings at 0.46 ohms, and this is a huge mistake. A lot of new technicians make they measure across the windings and they say, oh, that that resistance seems too low to me that the compressor shorted well no check it against copla, mobile, app and or whatever compressor, manufacture.

Data. You've got and you'll find that. It's probably just fine, because the reason why that compressor doesn't draw super-high amps like that is because, as that motor starts to run as that motor starts to speed up, get up to speed close to synchronous, speed. Sorry I got a bad cord there as it starts to get close to synchronous, speed, inductive reactance shows up an inductive reactance.

Is that magnetic resistance, since it's just a simple way of thinking? It that's opposing the force and it only happens opposing the current, and it only happens once that motor is up to speed, which is why, as that motor is speeding up, the current is high until that motor gets up to speed and the true impedance shows up Again, that's the resistance, a basic electrical resistance of the windings themselves, Plus that inductive reactance all mixed together and that's what that's what drives down your current. So what that means is is that if we were to just do Ohm's law on a compressor, we would think that the thing would draw crazy, high amps. Of course it does for that very first millisecond that very first cycle there is high current drawn inductive. Reactance is the impedance of the resistance that keeps the current down once that motor gets running more slip, equals less inductive reactance, so the more motor slips, the more physical mechanical resistance there is against the operation of that motor.

The higher the current is going to be because you have less resistance. Remember less resistance equals more current. Now, let's talk about what happens with voltage, okay, because I've done this. I wish I had the video that I could show you for this purpose, but I've got a an adjustable auto transformer.

I'm trying to remember what the name there's a there's, a technical name for that very AK. I've got a very act in the office, and so I can drive down the voltage to a to a motor and I've got a little blower 120-volt variac I plug it in and I drive the voltage down and so what happens on a motor when you decrease The voltage the answer is, it varies by the motor and the load that the motor is under, but at least in my lab and with the motor that I've got and it's a regular PSE, blower motor. It's got a capacitor on it. All that, when you drive the voltage down the current also goes down.

It just doesn't go down as fast as the voltage, meaning that you have two things going on at once. When you drive the voltage down on a motor on one hand, you're decreasing the applied voltage so that motor starts to slip as that motor starts to slip, it starts to use the voltage applied to it. The potential applied to it less efficiently. More of it is going to heat.

So what really happens inside of a motor when you apply inappropriate voltage when you apply voltage, that's too low to the motor, then that motor starts to run hotter in terms of it may not actually run hotter than it was before, but more there will be more Percentage of waste towards heat, so from a very practical standpoint, the motor will run inefficiently. If you apply to low voltage, the motor will run inefficiently. Okay, so that's that's one critical thing and eventually the motor will stall. So eventually, if you drop the voltage low enough, the motor will stall, but by the time it gets to the point that it does stall your voltage, at least in my testing, and it depends on the below the motor is under.

But your voltage is gon na. Be so low that even then your current will tend to be on the low side and again this is a curve. This isn't this isn't linear, you would have to every different motor would be slightly different and you'd have to test them independently. In order to know what the result would be, so the answer to that question is what happens when you reduce the voltage on an inductive load on a motor.

In many cases the amperage still goes down, but it's not linear like that, because as you're decreasing, the voltage you're also decreasing the inductive reactance, which in turn means changing the voltage on a motor, you're dialing, the voltage back and you're dialing the resistance back at the Time so inefficient, they don't run well they're, not doing the job they're supposed to do that's from a very practical standpoint, so the answer is: don't apply, voltage, that's lower than a motors designed for now. I was trying to find it, but certain manufacturers will also give charts to show, on a 208 230 to a 240 appliance like a condenser, how it will produce less overall capacity when you run it on 208 than you do on 240, and the amperage will actually Be slightly lower, so you'll have lower capacity and you'll also have lower current again on some of the church that I've looked at and I was I looked for 15 minutes. I couldn't find one, so I just let to let it be, but I've definitely seen that in the past. So if anybody wants to anybody wants to find that all right, let's see they've got anything else.

All right, yeah conclusion is no. What stays constant or the variables and the reality is, is that when you're doing electrical math very rarely do you only change one thing and the mistake that a lot of people make when they think that I'll lend here, because this is a common one when they Think that when you decrease your voltage, your current goes up the reason they think that is because they've seen things like on a 120 volt motor drawing double the current of a 240 volt motor. But what they're missing is. Is that that motor say it's a three quarter horse horsepower motor but have them sitting next to each other.

Once 2:41 is 120, and you know the one that 120 draws double the current, so you just assumed lower voltage equals higher amperage. Well, no, it has to be double the amperage in order to still do the work so in order to in order to produce the horsepower in order to produce the wattage of output, you have to design the motor differently in order to come up with. With that result, the same thing same thing is also true. If you do, I mean it's.

A good example of this is like I'm a motor. That's on a that's, an ECM motor. It's not a variable frequency drive versus a motor that isn't a PSC motor. When you take a PSC motor and you dial back the voltage, what happens the motor starts to slip? It starts to run efficiently so on and so forth.

You do the same thing. You dial back the input voltage to a variable frequency drive and what is the frequency drive do? Well, it can control its output, so it has a wider range of acceptability and that will you you, you back off the voltage slightly heading into a variable frequency driver into an ECM. You definitely will see an increase in current because you have something: that's that's actively. Changing the wattage actively impacting the output of the motor, and so it really depends.

You know what type of device are you working on, what the what the result will be, but assuming, for example, with a heat strip that, because it's a 5,000 watt heat strip that just changing the voltage is going to now make the amperage go up in order To keep the wattage the same, that's not how it works. There has to be something actively doing that in order to make that happen alright, so that is that we're gon na open up our our chat window here quickly. I do want to encourage you if you have not yet subscribe, subscribe, subscribe it to the HVAC school Channel. Please do so click the red subscribe button and then hit the bell hit the bell to be notified when we go live.

That would be much appreciated and then that way you'll actually know when these things go live because every time I do one of these afterwards people say I wish I would have known when you went live well. There you go hit subscribe, hit the bell and there you have it so we're gon na go ahead and bring up chat now, so I can see what y'all are Yammer and I want about what happens with the electrical during a power surge. How does that affect the motor, so that would be an increase in voltage when you have an increase in voltage. You're going to have you're gon na have a spike in in current as well, but, generally speaking, when you talk about a power surge like a lightning strike or from something with the distribution power supply, that's usually an instantaneous surge and those are very quick and the Only way to prevent those is to have so you know some sort of all of a sudden metal oxide varistor type system, some sort of surge protection system in order to help to help grab that current and shunt some of it to ground.

If that goes through the motor, if you have a surge high voltage that goes to the motor yeah absolutely can damage the motor because the current is higher and we all know that you increase, which current goes up decreased voltage current goes down. That's the reason why damages things it's current that makes things hot: it's that's the movement of the electrons and how many you're moving surge puts more around the device for the duration of the surge. Correct Renu says: are you working in the Virginia area and no, we are not. Let's see heap heap horse power equals watts, /, 746 right, there's 746 watts per horsepower.

That's all it is just a and, in the case of you know what we're doing we're generally thinking of it in terms of the the work that it produces. Are there any power surge protectors for blower motors I've already burned down on me? Suspecting a power surge, yeah zebra makes one, and that's specifically designed for ECM motors. Maybe Eric says ICM makes one, but you can get them that work on anything. Good quality want to work on anything my favorite device out, there's the ICM 493, because it also deals with low voltage conditions, high voltage conditions and surges all in one box.

It's not cheap, though most people that ask these questions don't understand what they are. Looking for. A simple answer to a very complicated question: it's almost never as simple as it seems. That's what Corey says and yeah that that is true, and in many cases we don't really need that full answer.

In many cases we don't need to do the math. That's you know again when I'm talking about technicians, we're not engineers, we're not designing new motors, nothing wrong with learning how to design a motor how to do the math. I'm really. I know some people who like to do that stuff and I do sometimes as well and it's a it's a good nerdy endeavor, but out in the field.

You do need to know what will happen, or at least that it is a bad idea to have under voltage or over voltage for various reasons, and it may not be as big of a deal if you are feeding that input voltage into something like a variable. Frequency drive, or it may be, a big problem like we see with certain models where, if you have over voltage into the variable frequency drive, it causes the actual entire board to fail. So again, it's all about knowing your equipment and knowing what the results are but like it. Like, I talked about in my initial story.

My misunderstanding of a heat strip resulted in me cutting a piece off and thinking that that would decrease the wattage or decrease the amperage and it didn't it increased it with no motor specs and an unreadable capacitor. Is there any way to find the correct sized cap, and the answer to that is here's what I would do in a case like that, I would guess at it. I would put one in and then I would use a power quality meter like the redfish or the new field piece and look at my power factor and just kind of keep adjusting until I get to one or as close to one as I can. That's the that's the simple answer, because in a lot of cases - and it also depends on your applied voltage - you know the manufacturer is basing their capacitor sizing on 230 volts.

So if you have more than that, your size may actually be off, and so starting to measure power factor is actually an interesting thing and you'll find in some cases that that sizing your capacitor based on power factor, you may actually may actually run a little better Again, it's not. It is a confusing thing, because that's not the only thing that capacitors doing is Korea's power factor correction, but if you get your power factor right on the compressor or whatever motor you're on you're gon na be you're gon na be in good shape. Chuck says: how does that find my cap size? Well, I don't know if you heard what I just said, but I said: try it so put one in you, you're not going to know beforehand. It's not like you're going to be able to know for sure what the right size is.

But if you roll up on a three-ton system and it's got a bad capacitor on the compressor and you can't read it and you can't read the compressor to find the specs to find, and you can't read the data tag then put in a 35 micro farad Capacitor and then check your power factor check your amperage check your power factor and if your power factor is, you know, 0.98 0.99. You you're pretty darn close to what it's supposed to be for that. If you don't know how to check power factor, that's fine! Most people don't, but you have to have a meter that does that, but that that's that's the way you would do it. It's not there's not like a easy way for you to it's not like.

You can just go measure the resistance on the motor and know what your power factor or what capacitor you should put on it he's got a got to try it, and I would feel totally comfortable doing that. I have a redfish meter in my bag and if I didn't have that data I mean I look at the. I would look at the motor itself. Look for the model number.

You can go back to the manufacturer and find it based on motor. But if you don't have that, then that's all that's all you can do all right. Well. Thank you so much.

Thank you all so much for watching and I'm gon na probably do another one. In the next couple days appreciate you and we'll see you on the next HVAC school Mythbusters podcast video thing.