We are here at the calo's offices and we're going to talk about one of my favorite topics, because it's one of the ones that creates uh some of the most angry uh social media arguments, uh we'll get to what that specifically, is when we get into the Middle of it, so let's see if you can catch on to where that, where that occurs, but we're going to be talking through breakers wires, otherwise known as conductors fuses and overloads and specifically nfpa 70 is a lot of what we're going to be talking around nfpa 70 is a national fire protection association, 70 guide, which is also known as the nec um, so nfpa national fire protection association, it's association right association, yeah sounds right is the organization that actually creates the electrical code, and the reason is because one of the primary reasons We need an electrical code is so that we don't burn down the house. Quite literally yeah. I don't know, i don't know who sings that song originally, but it's a good song really good song great lyrics. It was actually that that song was also written by nfpa.

Actually believe it or not so two different segments that we're going to be going through if you want to look it up and the reason why i do this right off the bat. Is that anything that i say if it's incorrect follow what the nec says i'm covering specifically how it relates to air conditioning, specifically mostly focusing on residential and light commercial, but it does go into some of the larger stuff when you go into really big stuff um, A lot of the a lot of the things i'm going to be talking about as far as what's on the data plates are quite a bit different, and so that's where sometimes i'll get a little bit of pushback. But ultimately, you can go and check for yourself by going to 310.15, specifically table b 16., so brackets b bracket 16.. If you, google, that you'll pull up like a thousand of them, that is the wire sizing, the conductor, sizing segment of nfpa 70 and then section 440 is specifically for air conditioning.

So, there's a lot of kind of unique things that little little nice easy exceptions that we get in air conditioning that makes uh in the end makes it a lot easier, but also creates a lot of heartache. When professional electricians don't pay attention to section 440 and they try to apply the other nec standards without looking at 440 and they think we're doing it wrong when in fact, actually we're usually not doing it wrong. This is one case where often ac guys actually aren't doing it wrong. Surprisingly, start with circuit breakers, what makes a circuit breaker a circuit breaker, what makes it different than a fuse aaron, i'm going to be turning to you a lot today, i don't want to make jd.

I don't want to make jd that's very early. What makes a circuit breaker a circuit breaker? Can you manually open the circuit? You can manually close it? Usually so so it's so it opens the circuit just like a fuse or a fusible link. Fuse is just short for fusible link means it actually opens the circuit and then stays open. A circuit breaker is generally that means resettable.

I don't know that. That's a universal rule, but when we say it, that's what we generally mean yeah. I don't know why. I don't call on jd because he did get the highest epa score of anyone.

I've ever tested, i'm still there you're still missing one of them yeah they just you just lost it, you just she. She just up and runned away, run off yep, so uh right after that. I made this illustration because - and you know of course, if you're doing this professionally, you already know this - that a trip breaker and an off breaker are not the same thing. A trip.

Breaker is going to go into the center position, sometimes they're going to have a little window. Sometimes they won't, but they have to be completely reset and then turn back on. We've talked we talked about this two weeks ago, but i want to cover it again quickly. Under what circumstances does a breaker trip? What causes a breaker to trip sure a short, a short is what again um whenever the intended path takes a undesirable course that shortly still makes something.

Okay, you said a lot of extra words there, but you kind of got to the point. You know it's good. It's good a lot of fancy talking there yeah, so it's whenever there's a path of lower resistance than the the design so and again, there's a lot of different ways of saying this, but electrons move from areas of higher potential to lower potential higher voltage to lower Voltage, in other words, there has to be a potential difference, and so, generally speaking, when we're creating a power supply or not, generally speaking, really always there's always going to be two sides to that power supply. If we're talking about you know a 240 volt appliance, it's the two legs of 240 120 on each side right, if it's 120 volt appliance, it's gon na be 120 volts to neutral.

If it's a battery, it's going to be the two sides of the battery. If it's a transformer, it's going to be on the secondary side, it's going to be your common in your hot on the other side, and so those electrons move in between those two sides and in order for them to have controlled current, they have to go through A proper amount of resistance, if that resistance is too low, it causes high current, which then trips, the breaker. So how much current is going to trip this breaker right here? How much current is it going to take 30 30 of a current? Yes, 30 of a current 30 amps, 30 amps, but here's the trick question. If we had a breaker like this one.

This is a squared eq, 02 pole and we were running a system that was drawing 30 amps. How long would it take to trip it? Might? Never drip now it should eventually, if we're drawing just a little bit over that 31 amps, it should eventually trip, but is it going to trip right away? No, it's not, and so we have to make quick distinction between things that trip breakers blow fuses, go out on overload instantaneously and things that trip breakers blow fuses go out on overload over time, because those are two very different categories of problem. Generally. A short circuit is generally going to cause this breaker to trip how fast boom right away right.

You got a breaker, that's tripping, you reset! It bam it trips again and then you just keep resetting it right. Is that what you're supposed to do? Yeah? Yeah? That's good because if that compressor is shorted internally now you're just creating more and more carbon and acid and sludge inside that compressor, it's great just keep resetting that bad boy and just hold it in place. You know try to hold it. No, so once a breaker trips don't keep resetting it and if it instantaneously trips you're looking for a short circuit, specifically most commonly a grounded condition, that's the most common, but you can have a leg.

Delay short as well all right a lot of different types of fuses. I don't expect you to memorize anything on this screen, but just kind of showing there's a lot of different types of fuses. We have your uh, you know your mini ones that we see in a lot of automotives. We have the you know.

The ato is the standard kind of blade type fuse that we use in air conditioning there's a whole bunch of different types of fuses, but there is they're all going to have a rating on current and they're generally also going to have a voltage rating. Now. What is that voltage rating on a fuse? What does that represent sam voltage rating on a fuse? Why is there a voltage rating on a lot of fuses? It's usually pretty high too amperage is what blows the fuse right. The current is what blows the fuse, but why do they have a voltage rating because there's a point at which you may not even have over current, but you have high enough potential that the clearances, the tolerances inside of that fuse, could cause an arc.

So each fuse has a little different insulation rating and all that so you wouldn't want to use a fuse that was rated for a maximum of you, know 250 volts or something uh on a 40 volt circuit or something it's not that it doesn't happen very often. But it is something to consider with a fuse, but there's another thing with fuses: another big difference in fuses. Does anyone know the difference between these two fuses? For example, i mean you can't always tell just by looking at them, but there's some there's some kind of giveaways here who you do what's the difference, uh one is a quick blow and one is a slow blow quick blow slow blow right now, i'm not saying That that's always universally! That's how they're going to look, but you have some fuses that when they get to their rating or above their rating they're going to blow really quick and you have some that are designed to not blow up quickly on purpose. So the amount of over current dictates the speed that it's going to trip right, but also the type of fuse dictates how quickly it's going to trip so on a fast blow fuse and again, like i'm sure, there's some rating out there.

That tells you exactly the amount of time based on the amount of over current price some table somewhere, we don't care. The main thing you need to know is is that you don't want to replace a slow blow with a fastball or a fast flow with a slow blow, because they do different things. The fast flow needs to you know protect electronics, for example. You don't want it to run even a short period of time at over current, but if you have something like a motor, anybody know what type of load a motor is.

What's the name for that type of load, anyone know sam inductive load right motor is a magnetic load and in an inductive load the current starts out higher. So you have that sto, the other start amps, and why does the current start out higher? Does anybody remember why why does the current start out higher in a motor? Yes, sam, the inductive load creates its own resistance, which is called what inductive reactants very close max knows the answers to all these things. I see them back there smirking inductive reactants. So it's a type of resistance that builds as that motor gets up to speed right and a kind of a related concept is back emf or counter emf.

Counter electromotive force that counter emf is what creates its own resistance, because a motor also acts as a generator. Once it starts getting up to speed because it has these opposing magnetic fields, but the point is when it starts up, it has high current and if you were designing everything so that way it tripped properly. When it was at running amps, then it would always be tripping at starting amps always be tripping straight up, tripping yo good times, all right short circuit. We already covered this short circuit, so we're going to kind of go over some quick.

You know dictionary definitions. If you will a short circuit in a device, an electrical circuit of lower resistance than that of a normal circuit, typically resulting from the unintended con contact of components and consequent accidental diversion of the current fancy words to mean something touching something ain't supposed to right. An open circuit is what something ain't touching when it's supposed to it's supposed to. How do you spell suppose, aaron s-p-o-s-e-d, okay exposed? That's how you spell that all right so overload is to place too much load on pretty easy.

It's like you know, it's like running a truck and you fill it up with too much. You know rock in the back of it. It's not there's nothing necessarily wrong. Well, i mean it is.

It is a key distinction because there's not anything necessarily wrong with the truck it's just you put too much on it. So to overload a motor, for example, means you put too much load on the motor. The motor is trying to turn against too much resistance. Physical resistance, interesting thing about motors, though, is what happens to the electrical resistance in a motor.

I'm going to dwell on this one for a second, because it's one that it really is hard for people to get their head around. What happens to a motor's electrical resistance when it's physical resistance is increased so when the amount of force that the motor is working against is greater? What happens to the electrical resistance inside the motor anybody care to take that one max? What's that decrease it decreases? Why does it decrease? Why does the electrical resistance in the motor decrease when the physical resistance against the motor increases it's not spinning as fast and when it's not spinning as fast it's not producing as much back electromotive force counter electromotive force, so it's acting less as a generator when it. When it spins slower and it acts less as a generator, it produces less of its own voltage. So therefore, it has less of that inductive reactance less of that resistance that the motor creates when it gets to full speed right so as a motor spins faster.

It creates more electrical resistance as a motor spins slower. It creates less electrical resistance and that's why it draws more current right. More electrical resistance equals less current. This goes back to ohm's law stuff, but sometimes we struggle with this because we get physical resistance confused with electrical resistance.

Those are inversely proportional in a motor and an inductive motor. Getting any of that mario you're, giving me that deer in the headlights look, but i i appreciate it: it's okay, all right! So when we say overload, we can just mean to place too much load on so why? How could you overload a compressor? We talked about this for the last couple weeks. We've talked about this. How could a compressor be overloaded? Could it be too much refrigerant sure i mean that wouldn't create an electrical overload, because that would slow it down.

Are we talking overload mechanically or electrically we're talking about because they're, actually, both the same in this case, so you overload electrically when you have too low of electrical resistance and therefore too high of current. So in this case, load and load are proportional. It's the resistance. That's inversely proportional, but if you were overcharged with refrigerant, you would be adding physical load correct.

That would reduce your electrical resistance, which would increase your current. Yes, yes, not resistance, load right, correct, so resistance, electrical resistance and physical resistance are adversely proportional, i'm not going to smile, i'm not going to smile. It's okay and overload conditions with physical overload and electrical overload is too much current. Those are proportional to each other.

So, with a compressor, that's just come out of defrost. The system has just come out of defrost. What's what happens to your suction pressure in a system? That's just come out of defrost and the evaporator coils are all really warm. Your suction pressure is really high right.

So you could potentially have suction pressure, that's so high. So when suction pressure is high, what happens to your refrigerant density and your suction line? Is it more dense or less dense? It's more dense, right, higher pressure, more density, so more refrigerant is coming into that compressor. What happens to your compressor current when that happens goes up right? We talked about that. So does anybody know what this thing in? Behind these words is called? It's not a very great picture.

Are these called you don't see these in residential by the way? This is a commercial thing: marshall, industrial! No, this is called a starter. So if you ever hear the term a starter, a starter is just a contactor and an overload mashed together in one in one unit, so it actually can shut down a particular individual component based on the current being too high overloading. So it's basically like a contactor and a circuit in an adjustable circuit, breaker put into one component and you'll, see that a lot in uh bigger units and they call it a starter which is an annoying name. It's really, it makes you think.

It's a start capacitor or something at least for me, but it's it's not all right ground fault, we're defining a lot of terms right now. So that way, this all makes sense, because, when you get into the nec like it, it becomes kind of important that you understand the differences between these things. Ground fault, the momentary, usually accidental connection of a current carrying conductor to ground or other point of differing potential. Very similar to a short, but specifically, it relates to a certain type of electrical fault, and that's especially when you have a circuit that has a gfci.

Have you ever heard of that before gfci or gfi and little buttons that you reset that always trip all the time? The bathrooms and garages? That's ground fault circuit interrupter, so that specifically, those are specifically designed to look at for imbalances on the legs. On the two legs and if there's an imbalance in current, that means that some of that current is leaking to ground to some other path and that could be unsafe. So we have insulation breakdown and all that now, specifically with ground fault in the nec national electrical code, the 2020 - i believe it's a 2020 nec - specifies that we're going to have to start having gfcis on condensers and that's going to be a very interesting uh. You want to talk about a new, a new form of nuisance.

Call it's going to come up a lot in the same way that you know ground faults, tripping garages when people hook up their uh old refrigerators to them. We're gon na start running into that. You just say: weight guys have to be on the system. They're gon na they're gon na be most likely in the disconnect or in the breaker that feeds the condenser, not the air handler.

So it's got to be things so there's some reason why? I don't remember why the 240 has to go through the gfi yeah then disconnect and then system. Well, it's going to be integrated into the into this. It's going to be a gfi breaker, it's going to be most likely, so it'll just be a lot more expensive. Okay, all right over current protection is a form of protection.

An electrical circuit that prevents excessive current, usually at a predetermined value, usually refers to a type of protection designed to deal with instantaneous spikes and current okay. So over current protector is more so designed to deal with instantaneous spikes. That would be your circuit. Breaker would be an over current protector right, so big spikes overload.

So, let's this is a big distinction over current circuit breaker fuse overload protection is a protection against a running over current that would cause overheating of the protected equipment. So you got a compressor that uh is running hot because it's got no refrigerant in it or because it's got a clogged condenser coil or because it has way too much refrigerant or because there's some other problem where it was in a hot pool down for an Excessive period of time or whatever, those are all overload, conditions and those can be either thermal overload that are protecting a device just based on its temperature. For example, if you have a system, that's running low charge, it will trip a the internal overload right, but is that compressor, overloaded, physically meaning, is the compressor drawing high current when it's low on charge? Does this system does the compressor draw high current when it's low on charge? The answer is no because it actually has lighter suction gas coming back to it. So it's actually not working as hard, but it goes out on overload not because of a current issue, but because of a temperature issue right.

So, in many cases, overloads can play this double this double purpose and specifically in a compressor, we're looking at that internal temperature of that compressor and that's what it's tripping based on. It's going to protect against electrical problems and it's going to protect against other overheating problems. Alright, so let's talk about sizing conductors, so what is a conductor? Just a wire right can be made of copper. It can be made of aluminum whatever so wire.

So these are the factors we got to consider when we're sizing an inductor first off. What is the circuit amperage? What is the current in the circuit? We have to think about the instantaneous and the continuous. Now again, i'm not going to tell you all the math of how to do this, because that's not our job. Our job is not to do complicated, math, i'm going to tell you the factors that relate to this, so that you can pay attention to outliers and we'll talk more about what that means.

But if you're, if you're power energizing a circuit that has a motor in it, you know that it's going to have a higher. Generally speaking, this isn't always true like with an ecm. This isn't true, but in a psc motor it is or three-phase motor or whatever um you're going to have higher instantaneous current and then it's going to go down to its continuous. You have to think about the ambient temperature.

Is there an abnormal ambient temperature condition that this conductor, this wire, is running through? You have to think about the insulation temperature rating, which is one of the biggest things that we don't consider and we'll look at that. You have to look at box or conduit fill. This is a very specific electric electrician thing and it's a really big thing for electricians. If you have a box or a some sort of a raceway, something that you're running multiple conductors through, you have to think about how many are in there right, because that heat that builds up in there is cumulative and what we're really looking to make sure doesn't Happen is we're looking to make sure we don't compromise any of the insulation.

We don't want the insulation to melt off insulation melts off. We got big problems, so that's what we're trying to prevent again. Remember: nfpa national fire protection, where they're trying to prevent fires. Yeah they're trying to keep it from getting shocked, but primarily they're trying to prevent fires.

That's the main thing here, so things like box fill is important and then voltage drop now voltage drop from the nec is a suggested. Maximum voltage drop really, ultimately, with voltage drop. All that matters is, are we delivering voltage? Are we delivering potential to the appliance that the appliance is designed for so as an example with a residential ac system, it's going to be very difficult for us to deliver a voltage. That's too low a lot of people.

It can happen in a brown out condition where there's like a significant drop, but under normal circumstances, it's going to be really abnormal that we drop low enough, because all of our i shouldn't say all but most of our single phase. Air conditioning systems are rated for 240 volts or 230 volts or 208 right, so that means they're designed to run at 208 under normal conditions, because they're designed to work on two phases of a y, uh commercial, three-phase power supply, so they're rated all the way down To 197 - and it's going to be pretty rare - that you're going to test voltage at the end of a wire and find that it's less than 197 on a residential application. Now, in three phase cases, commercial cases with long runs of wire, you very well. Could you know you, we work on self-storage facilities that have these multiple stories and that's where starting does become a problem and it can become a real challenge, but voltage drop is all about just providing the right voltage to the unit.

While it's running it's, not the nec doesn't really care. If you have voltage drop, if that voltage drop is within the amount that's acceptable to the appliance you're connecting it to that makes sense, a lot of people will say, like you've, got a size to voltage drop. That's not an nec thing, i mean it is kind of they give this suggestion of four percent max, but it's not actually part of the code. It's not required.

They want you to size conductors so they're not going to overheat. They don't really care if, at the end, the voltage is too low because that's not going to cause a fire. It's just going to cause your appliance not to work, which you know. They don't really care that much about here's a lot of words starting current.

I'm not going to read all the words, but starting current is when the first, when the voltage is first applied to the windings, there's no back emf, so it's always going to be high initially, for those first couple cycles running current is what it is once the Motor is up to speed and that back em after counter emf is in place causing inductive reactance, which gets that electrical resistance up and gets your current down and then lock, rotor, current or lock rotor amps is if that motor is remaining locked. What is the? What is the current it's going to draw if it stays locked? It's not physically moving five to six times your regular running. Amps is what that's that's, what that's going to be all right. So, let's talk about what happened in these cases.

Let's start, let's start being kind of practical here, so what happened here well, first off? What are we looking at anybody know yeah we're looking at motor windings here, and so what happens when, when you see this, what a new motor yeah? Well, that's for sure somebody! Let done let the smoke out. We know that. But what what happened here? It's a short uh. But what happened? What came first, did it short and then that melted, the lacquer off the wires or did the or did the lacquer melt off the wires? And then it shorted yeah, the lacquer was most likely compromised and then it shorted - and this is actually an interesting thing with motors - is when you're talking about something.

That's got all you know, there's a rotor in there. That's spinning around really fast. What would happen if a shard of metal got into that? Maybe bearings came apart or whatever and flew into that into that winding? What's going to happen to the winding, it's going to compromise the lacquer and it's going to short the winding. So in many cases mechanical problems cause electrical problems right many cases.

That's that's. What's going on, especially inside of a compressor where everything's in there right and something goes wrong and now it starts bouncing around you know, maybe it loses its suspension or maybe there's you know, metal particles that have gotten in there that can compromise that lacquer and uh And then that results in that, but it could be the other way around too i mean it's possible um, it's possible that there was just like a really high current event or something like that. But again, even then it's it's compromising the locker. First, that's what's happening.

First, what happened here? Do you think field breaker? Okay, it's fairly obvious. What do you think? What do you think happened? The connection got loose. The panel connection got loose. This is a really interesting one.

What happens when a connection gets loose? Arcing sure not necessarily it doesn't always arc it could it could be, but you could have a bad connection that isn't necessarily arcing. So what what goes on in a bad connection? What does that mean electrically? You reduce the conductor, size, you're, reducing the conductor, size yeah. So it starts to get hot right, so you're, reducing the contact area and so there's two different sides to this, because a lot of people will say well, yeah that creates more resistance and resistance, causes heat and that's a tricky business, because if you increase the resistance In a circuit, let's go back to ohm's law in the video we'll put a let's like throw a little ohm's law up here. What happens if you increase the resistance in a circuit? What happens if the voltage stays the same, which it does right? We're not something's going on in this with this circuit breaker.

It's not like. All of a sudden. The power company is changing the voltage, because this circuit breaker is not connect connected well right, so voltage stays the same. We increase the resistance.

What happens to the current? If you increase electrical resistance, what happens to current goes down. That means that, in your circuit, you have more or less heat overall, when your current goes down, you have less overall right, and this is why it gets kind of tricky when you and people it really. The end at the end of the day, it's not that big of a it doesn't really matter. We know we need to have good connection, but the resistance does lead to a problem, but even more than that.

The the lack of ampacity amperage capacity through that connection leads to heat in that area, which then leads to more carbon there's at least more heat, which then leads to more resistance. So you're going to get a couple things before this thing failed completely. Whatever was connected to it, had a pretty high voltage drop almost almost assuredly because you had resistance in the circuit, which is dropping the voltage, which is actually dropping the current. So, whatever it's connecting to it's not running well until eventually it just keeps that surface contact size just gets smaller and smaller heat gets more and more until eventually, it melts right so making good metal to metal contact whenever you're making connections is key.

Why? Why did what other reasons could this happen other than poor contact, uh, it's possible and actually there's. There is one factor here. In some cases, people will try to jam like much too large of wires underneath breakers, and then they end up cutting strands off or whatever, and so that can create a hot spot that can do it um, but more than likely more likely, it was just a Poor connection, but you could have a breaker that just didn't trip and it had really high current on it over an extended period of time. That can also happen potentially most likely just a poor connection.

In a lot of cases, it's a poor connection where it actually attaches to the bus. They may have never got it fully snapped in, and so it was just kind of sitting there bouncing on it over extended period of time or if somebody used uh removed the tabs to put quads in the panel that doesn't accept them. Yes, so when you remove the tabs to put quads in the panel that doesn't accept them, i never knew anybody who would do anything like that. Definitely not me you'll see here.

This is referring to uh sizing table. This is the wrong sizing table. We've selected copper as our conductor, type and you're going to notice. We have three separate columns.

Why do we have three separate columns? Different temperatures, different temperatures right, yeah, 60 degrees celsius is kind of our standard rating and you'll notice. It kind of lines up right. 15. 20.

30. 40. 55. 70..

That's what we're used to quoting uh yeah for some reason. A lot of you think that, but no it's not and that's for a 60 degree celsius, installation on your conductor and conductors you're going to say on them. We'll show a picture here in a second conductors are going to say on them what the celsius rating is for that connector. Why do we usually use this column? Because that's what romex says on it? Because that's what romex is right? Romex is trade name for nm non-metallic wire and there's a lot of romex in residential houses, and so, if you're using romex, you have to use this column.

If any part of that circuit is romex, you have to use this column right, but that a lot of the and the more advanced table that comes from the nec will actually list all the different types of wire for each column. So they kind of make it easier on you, but you can always just look at the conductor, just see what it says. So if you're using romex any part of the circuit is romex, this is the column you need to use, but if you're using 75 or 90, then you can use these two columns, so you could potentially put 25 amps or 20 amps on a 14 or whatever. If you have, if everything in that circuit is rated at 75 degrees celsius - and it's copper now there's another trick to this - is that everything has to be rated for that, including the termination points.

So all your wire nuts any uh, you know any lugs in your contactor lugs and your breaker. Everything has to be rated that way and they are they'll. Tell you, if you look at if you look it up, it'll tell you what the uh insulation rating is for all of those. What the temperature rating is for all those now also, the other caveat, is on any tightened connector there's also a torque rating that you got to follow in order to actually hit that hit that level.

So a lot of people just say: hey, look we're just going to use this column so that way we're safe. We don't have to worry about it, no problem. This is like sort of your. You know your safe space.

So, if that's what you're using and you want to be safe, this is fine to use that column on the left. But it's not always the case and so a lot of times people tell somebody they've got to rip the wire out and it's not the right size. It's undersized, but maybe it's not maybe it's all 75 degrees celsius or 90 degrees celsius and in commercial industrial you'll. Also see 105, so it can handle more if you start to pay attention wire sizing that manufacturers put inside units you'll catch on pretty quick, that it doesn't really jive with what you know what we have to put in as it attaches to the appliance they're using Smaller wires and that's because they're using better insulation ratings but aluminum or copper, clad aluminum much different, so it starts to i mean it's not it's not hugely different, but it is different.

So you have to pay attention if you have aluminum or copper, clad, aluminum right. Sam, i mean it ended up being the right size. I guess didn't it, so i made a real fool of myself. Didn't i i sure, did you also have to think about differences in ambient temperatures, so these tables that i just showed you are based on a 30 degree, ambient in 30 degrees celsius, ambient temperature, which is equal to 86 degrees fahrenheit.

If you have temperatures that are significantly greater than that or lower than that, you can use a uh, a d rating or an increase rating. So if your ambient temperature is significantly lower, you can actually use this multiplier to multiply the amount of current that it can. It can go through now again. These are maximum temperatures.

Here's another interesting thing: do we ever run wires through spaces that are more than 30 degrees celsius? 86 degrees? The answer is yes, so it's another reason that we might want to go ahead and just stick in that left column. You know just play it safe, but technically, if we were doing everything we were, if we were doing everything by the book, we would have to go and say: okay, what is the maximum temperature of this attic? Let's use this d rating factor. I think nm actually has there's like a exception or something then so when i say that i'm not saying that work that that i know for a fact that you're supposed to do that because they're in the nec there's all kinds of exceptions to every rule. But this is there for a reason, all right now: here's where it starts to get really controversial.

It's actually not controversial at all. It's super straightforward and there should be no controversy, but it's a misunderstanding by electricians that results in um this problem. So the saying that electricians repeat over and over and over again from the time that they leave the womb is that the circuit breaker is there to protect the conductor right. They'll always say that the circuit is breakers to protect the conductor, and so, if you have a conductor, that is a number 12 if you're going to use the first column, number 12, copper.

That means that the circuit breaker has to be what a 20. that's? What they'll say, because you don't want to run the risk of it having an over current condition and not tripping the breaker melting the wire right? Let's take a look here: minimum circuit amps 31.4 maximum circuit breaker 50.. What does that mean? Well, a lot of people will say that means that you could oversize the wire and then put a 50 amp breaker on it. If you want it, that's actually not what it means, and this is not disputed territory.

This is just a fact how it is. You can size your wire based on this number and you can put in this circuit breaker, which means that the circuit breaker is not protecting the conductor under all circumstances. It is protecting the conductor for a ground fault, condition, we'll go back to our to our conditions. Here, it's protecting the conductor from a ground fault, it's connecting potentially a ground fault, a major ground fault and a over current situation where you have an instantaneous spike.

So a big problem, shorter compressor, whatever it's not protecting the circuit from an overload problem, an overload condition people say: well, that's a problem we'll get into why it's not so it's okay. To put, let's say that we're using a um we're using the first column so 31.4 and it's copper, what size wire? Should we run to that condenser if we're using the first column? Eight, all right, eight is forty. Thirty one point: four: is minimum circuit amps right now. Minimum circuit opacity is what it should say, actually that this is like an annoying thing, because this isn't what is minimum circuit amps mean like the minimum amps circle run.

It means minimum circuit and opacity, meaning the circuit must have the wires connecting this unit must have an amperage capacity that can handle at least 31.4. Now, if we have a 75 degree conductor, then we could use number 10 wire if the entire assembly is rated at 75 degrees. Let's look at this linux over here see i like linux is this: is an old linux data tag? They say it better. Minimum circuit and the minimum amp amperage capacity of the circuit 28.6.

What size wire can we run to that? If it's got romex running to it number 10 right what size breaker? Do we put on it 50, amp breaker? Does the breaker protect the conductor? No, it does not not fully. It protects the conductor against these severe spikes in current that happen from a short circuit or ground situation, but it's not going to protect it if the compressor's just running too hard right. So what protects the circuit if the compressor's just running too hard the internal overload on the compressor is what protects that and the fact that that appliance has an integrated internal overload is what allows the manufacturer to put these rating stickers on here. So do you think the manufacturer is putting this on here and they're just kidding like they didn't do the math? They didn't already look at the nec.

Of course they did they're telling you you can put in that's the maximum fuse size. Does that mean you couldn't put in a smaller size? You could put in a smaller size yeah only because even it only because even a breaker can have an opacity but yeah. You could potentially put you know anywhere from a 35 to a 50 in there. Now inspectors aren't going to let you because they don't understand what they're looking at either so don't even start with them.

But here we could have a 50 amp breaker on a number 10 wire and it would be completely allowable by the nec again go back to the nec or look at michael's videos on this. If you think, i'm crazy, because a lot of people will argue about this like every single time all right - these aren't great images here. But if your torque for 75 degrees celsius is 22 inch pounds if they're screws and 40 inch pounds if they're lugs. So, in order to get the full 75 degrees out of this bad boy, you would want to make sure that you are actually using your handy, dandy, torx screwdriver, that you always have in your pocket and torque that bad boy down to exact torque specifications.

And if you want to be extra safe, just put a little nylon on it first, that was a joke. Don't do that? Don't do that so same thing! This is just a zoomed out view just showing the same thing, but look up here, this conductor. What does it say on it? 90 degrees? So let's say we had these conductors connected to an appliance, but you were terminating them at this contactor meaning you were connecting the high voltage conductors to the bottom of a contactor, which is often what we do. What is the celsius rating of that circuit now? 75 right? So if you wanted to make it higher, you'd have to put in make sure that everything down the line, your disconnect your breaker, everything was rated at 90., but sometimes that may be the thing to do.

Sometimes, if the option is between changing all your termination points to something that can handle it or re-running an entirely new circuit, that may be the thing to do now. A lot of people just say: hey, it's no problem just run number four wired everything and there's no problem. Okay, like sometimes you're talking about applications in multi-family or commercial or there might be multiple floors there might be. There could be all it could be.

A major deal sure if it's just a matter of running a new whip to a breaker panel. Well then, fine, who cares put as big a wire as in there as you want so long as the termination points are designed to accept that correct wire. There's. Also, this weird exception with uh.

I don't know if you remember the whole bruce wells thing with the uh undersized ground in some applications is like some weird exception on why even using romance oversize sometimes could be a code violation. It's a weird exception. In general, you can't run romex to the outdoor unit anyway, correct good point. Nathan makes do you know why you can't run romex to an outdoor unit.

Anybody know! Well, you can it's just against code, it's against code. Yes, the reason why you can't run romex to an outdoor unit, even if you pull it in car flex or some other seal tight, is because it is not rated for damp conditions. So outdoors, even within conduit anybody, any sea is considered to be a damp condition and you are not allowed to run nm, which is the correct. The correct designation for romex in a damp condition.

So, that's why you should either use the pre-made whip or use a whip and pull proper proper conductors through it. So when a lot of people focus so much on the size of the wire, it's just as important. Here's. The main point i'm wanting to make just as important as the size of the wire is the insulation rating on the wire a lot of people.

Don't we're just putting a bigger wire just put in better insulation rating six and one half knows the other they're both performing the same thing other than that bigger wire does serve to reduce voltage drop higher insulation rating. Does not higher insulation rating keeps it from melting, but the voltage drop is going to remain the same, because the internal conductor is the same either way. So if you're trying to beat voltage drop, then you've got to put in bigger wire, but very rarely are we trying to be voltage drop so does that? Does that make sense on the voltage drop versus the insulation side because they are different and a lot of people get those confused. So if you're really close to the wire being the right size, you just wrap it in electrical tape, increase that insulation and you're done.

That gives you at least one extra amp. Does that work? I'm glad, i'm glad you have a microphone on. It's very helpful. What i want to know is how did that water bottle, get balanced on the side of that purlin up there like that? That is really did that actually happen.

Are you serious? That's the real story. You bet him a hundred dollars and then he did it and you did you pay him a hundred dollars, wow i'll poison. You he's very he's very poisony, wow huh yeah he's got his mama's jeans huh. He feels like up right.

Yeah he's just that's what you could say: that's your excuse, i'm an upright! I mean i mean on the cap. Yeah, that's does it actually have anything in it? Okay, i'm gon na have a hard time focusing now so, like i mentioned in residential, it's very rare that voltage drop is a real problem other than two reasons. One. Is that there's a bad connection somewhere like a significantly bad connection, and the other is if the power company isn't giving you the proper voltage in the first place? And that's not really voltage drop? That's just the power supply problem right when you get into commercial voltage drop, becomes much more because you're running these really long conductors now.

Is it possible? You have some really big custom house with a panel on one side, and you know it is possible, but again unlikely, because with residential equipment, it's designed to go all the way down to 208 anyway, because it's designed to also work in three years, if you're doing Like a sub panel and like an outbuilding or something yep, if you're feeding a sub, you know, maybe you have a sub shop right. You know you're, making some delicious submarine sandwiches that could do it. Um you shouldn't put those in your house. It's not code! The confusion that a lot of people have is they imagine that when there's voltage drop, there's also a hot circuit, so they imagine the circuit's getting hot when there's voltage drop, but actually that's the opposite because go back to ohm's law.

If you decrease voltage what happens to current decreases right now in a inductive circuit, it's not completely linear. So a lot of people will say: well if you run lower voltage to a motor well, that motor that motor will draw a higher amperage and actually nathan, and i had to argue about this one time you arguing about this one time and you were right. Remember we were doing all those tests with the testo meter and all that i like to remember when i'm right about things: yeah. Okay, that's a sign of really low ego, but i don't remember you're an egoless boy.

Anyway, you were right. We actually tested it where we, where we created a voltage, drop going into a unit and just kept dropping the voltage lower and lower, and the amperage went lower and lower until the point where the motor stalled completely. And then it went to clock rotor. But that lock rotor was a much lower, lock rotor, because the amp, because the voltage was lower.

So when you put lower voltage to something you actually drop its current and you also drop its capacity. So this is actually an interesting thing. If you pay attention to residential single-phase units, they may be rated at. You know 1415 seer, but when you connect it to a 208 power supply, it actually debates its capacity and its efficiency.

So it doesn't work as efficiently and it also doesn't have the same capacity when you drop that voltage, because the motor actually slips more. It's not actually spinning as fast the synchronous speed actually decreases. It's not a lot, but it's enough that it does affect the capacity and the efficiency of that unit. So, the point being that we worry about voltage drop that has to do with length, because that results in voltage that's too low to the unit that could cause problems that doesn't cause overheating too long of wires doesn't make things overheat in terms of like the wire Conductor itself, too, small of wires does and installation ratings that are too low, do or wires that are run through too hot of spaces or too many wires run together.

Those are the things that cause fire issues and therefore those are the things that uh nfpa is concerned with. If you start looking at electrical data, this is from a carrier unit. They make it so ridiculously easy, like you do not have to overthink this. So, for those of you who are like the data doesn't mean that we'll take a look at this, we got a 410 unit here 48.

We go over the mca, minimum circuit, ampacity carrier and passity is 26.1 and you're like well what size where's that! Well, you don't have to guess they tell you 60 degrees, it's 10. 75 degrees also, 10., all right, so you're going to run a 10 number you're going to run a 10 wire to this maximum length at 60 degrees maximum length at 75 degrees. I don't know why that's kind of confusing there. I think they've got a little mistake there, but regardless, why are they giving you that maximum length? Are they giving you that, because of the nec, no they're giving you that maximum length because of their desire to keep voltage drop low to the appliance if wear is applied at an ambient greater than 30 degrees celsius consult table 310 16 of the nec and fpa 70., the empassy of non-metallic sheath, cable, nm trade name romex shall be that of 60 degree conditions for the nac article 3, if other than uncoded blah blah blah blah blah blah blah blah blah blah blah all the stuff that i just said right there in the Manual that says it all every single thing right all the important stuff is right here in the product data for this unit.

So it tells you number 10 wire. What's the maximum fuse or circuit breaker 40., there's no confusion here, so many people will say no. You got to put in a 30 because you put number 10 wire, it's incorrect. You can put in a 40., you could fit in a 32 if you want it, but again you can't you're not going to find a 32..

It's a very hard breaker to find it's very specialty. You know you got to know people who are going to say you're going to say something. I guarantee you you're. Looking like you're going to say something.

I promise. I promise you oh here. It actually even describes length shown is as measured one way along the wire path between the unit and the service panel for voltage drop not to exceed two percent so they're trying to ensure that you're not gon na see two percent, it's actually four percent. Overall, i think - or maybe it's three and two something like that - it might be five but they're, saying between the service panel and the appliance not to exceed that in order to keep your voltage drop, two percent or less.

I want to address specifically the situation that you had sam, because this is a question that comes up a lot. So if you want to loudly describe what it was and then we can kind of talk through it. Oh boy loudly, that was a large aluminum wire. Being fed from the outdoor main panel to a small junction box, slash breaker box, which then fed from one breaker to another sub-panel which had its own set of breakers and then fed.

They can answer an air handler right or something like that. Okay and the question then becomes like okay: how do you size breakers and conductors that feed sub panels that then the sub panel feeds and like there's, multiple things and here's? What i want? Here's basically the thing i want to clear up, because i'm not saying that as an ac technician, you're going to do these calculations, i don't want you to. You - should hire a professional electrician to do that. So i'm not saying that as an ac technician, you're going to make those calculations, but here's the principle.

First off you don't have to add up all of the breaker sizes and then size, your breaker or wire off of that. Like that, that's not how that works. I mean you think of convenience outlets as an example. You'll have multiple convenience outlets in your house that are connected to a 15 amp breaker or 20 amp breaker, we'll say 15, because a lot of houses are right.

So imagine your house, you got a 15 amp breaker, it's got number 14 wire and it's wired up to all of these outlets. What prevents you from going and hooking a toaster up to one outlet, a vacuum cleaner up to the other and a space heater to the to the third and firing them all up? What prevents you from doing that? Nothing prevents you from doing it. It's just going to trip right, so it's safe! Why? Why is it safe, it's safe because we're going to go back to what electricians learned since they were little babies, because it's actually a really good thing to know it is a good rule. The breaker protects the conductor right, so at that point it doesn't matter what you hook up.

If you exceed for any amount of time that 15 amp rating it's gon na trip, it's gon na trip before the wire, the conductor is compromised, make sense, which is why, when we have this special rule in section 440, that special rule is for dedicated circuits right. We're not taking an air conditioning, uh circuit and then tapping off of it and powering a water, softener and then tapping off and putting an rv outlet. You know next to it or whatever else right. We couldn't do that, because in that circuit, that circuit is designed.

Specifically for an appliance that has an internal overload right. That internal overload is there to protect it. The internal overload is what fills that gap in between the wire size and the breaker size, but whenever you have these sort of multiples, it goes back to that same rule. The rule of the breaker protects the conductor right.

So if you're feeding a we'll go back here, real quick - so let's say the main wire that's going to this sub panel is a number four okay, let's say it's in it: what was it? What was the wire size? In that case the aluminum wire? It was a four okay, so we're gon na go to aluminum. That's it! It was aluminum four, if it's in the 60 uh. If it's in the 60 category, then that can feed a uh that can have a 55 amp breaker maximum, protecting it, because there's multiple things on that circuit, so it doesn't matter what happens if that wire is properly terminated, properly connected, nothing loose or weird, and it's A number four wire and it's got a 55 amp breaker protecting it. If you try to put more than 55 amps on it, what's going to happen, it's going to trip right, so you can have a sub panel, because this will come up a lot of times.

You guys will see all right. I've got a sub panel, it's being fed by a 60 amp breaker and it's got a we'll say: it's you'll see it's copper. It's got number four wire, copper going, you know in between it, but then you go into the sub panel and it's got a 60 and a 30 in that. Well, that can't be right because you've got a 60 feet of 16 or 30..

So long as that conductor is right, then it's fine, because that breaker is protecting that conductor as far as we're concerned, because it's not our job, we're not the ones engineering, the original electrical system, but we're there to be the ones who say, wait, there's a problem Like so, this is knowing this helps, you say: wait, there's a problem. It doesn't make you ultimately responsible for everything that goes on in the structure. So that's the difference between being an electrician or electrical engineer, an ac guy, we're not expected to design these things from the ground up we're expected to throw the flag on the field and say this circuit needs to be rerun because it's a problem, but the point Being that in a lot of cases, inspectors and electricians think circuits need to be run when rerun when they don't. Because of these two things.