 Hey, bolt drop calculations can sometimes be frustrating and confusing, but they don't have to be. Let's get to it Hey everyone Chad here from the Electric Academy Continuing on with my series on code calculations. This week We're going to be doing how to calculate a bolt drop So basically how to figure out how far you can run certain conductors Next week I'm going to be touching on how to size the conductor using the same tables And if you want if you just want to click up ahead there you can go to last weeks and I talked about wire opacity So this week what we're going to be doing is talking about bolt drop using the Canadian electrical code So we'll be jumping around into section 8 and then appendix D for those who are following along with the NEC the national electrical code I'm going to be using the CEC So a lot of the principles would be the same but the rules themselves would be completely different because obviously we use different codes What I would love is if somebody could in the comments below put which sections the NEC covers The bolt drop calculation and that would be a big help to me because I'm always loving to learn and I also know that a lot of you Are in the States and not in Canada. So this code stuff does not necessarily apply to you But again, like I said, a lot of the principles are the same. So let's just get right to it here. Shall we? So first off, we're going to look at 8102 and so it says see appendices B and D We're going to jump into D in the second here, but it says here 102 says the voltage drop in an installation shall be based on the connected load of the feeder or branch circuit if known Otherwise, it should be based on 80% of the rating of the overload or overcurrent device protecting the branch Circuit or feeder and not exceed now. Let's talk about that before I jump into the A and B here So several ones basically telling us when we're dealing with volt drop calculations We're going to be dealing with the current because current and resistance creates volt drop So what this say is if we know what the load is say, I've got like a hot tub or something that draws 60 amps Then I'm going to go ahead and use 60 amps because I know what that load is I know that that hot tub is drawing 60 amps But if I only know the size of the overcurrent device and in this case, let's call it a breaker or a fuse Let's say if I had a device being fed off a hundred amp fuse Well, then I'm going to use only 80% of that and I'll go into a video on that 80% rule later on but right now just take my word for it Well, it's in the code take the codes word for it that you take that at 80% So a hundred amp circuit breaker or a hundred amp fuse you would size this at 80% of that or 80 amps Next we've got items A and B here and it says that they should not exceed You keep your volt drop can't exceed 3% in a feeder or branch circuit or 5% from the supply side of the consumer service or equivalent to the point of utilization Got a little drawing drawing up here for you now when they talk about the 3% What they're talking about is from the breaker all the way over to the point of utilization So that's where the plug would be or your load basically. I've just got a picture of a plug there But you know what I mean? I could have a load of disco ball. I don't care what you have But the load is at the point of utilization. That's 3% which when I'm teaching my classes I say about 95% of the time. We're using the 3% rule What the 5% rule is is we're not to exceed from the supply side So where we supply makes their or hydro or whatever the utility makes their connection here to the point of utilization That can't be exceed 5% from that point to that point once in a while that'll come up But again for the most part we're using the 3% rule which would get us right into here From this point, which is our breaker all the way over to our point of utilization Which would be the plug and again motor whatever you want it to be all right moving on What I want to do is I want to take you through the steps in how to figure out these volt drop calculations now I said 8102 which is great because that tells us that we're going to be using Either the size of the load or 80% of the overcurrent or overload device protecting it But then it tells us to go to appendices D and I'll go through those steps with you So these are the steps that I always take and I'll put these steps actually down in the description below So you have access to them But step one is determined if the load is known or if it's fed from a breaker of fuse So I'm going to go through two examples showing both So we'll go with a known load first and then we'll go with a breaker or overcurrent device after Step two is determine the one-way distance at 1% and 120 volts now That's table D3, which I'll show you what it looks like in a second here Table D3 gives us a distance for different sizes of loads and different sizes of conductors But it's only at 1% and only for 120 volts So we just saw from that code rule 8102 that we were not to exceed 3% For a branch circuit, which is what we're going to be doing or 5% from the feeders of the supplies authority But we're going to go with the 3% So we can't exceed that and 120 volts. Well, not everything's 120 So what we do is we divide that voltage by 120 Step three, we're going to multiply to allow for the 3% or 5% volt drop Step four, we're going to determine the factor for voltage. Now again, we're going to take the voltage divided by 120 So if it's 120 volt load, well then it's 120 divided by 120 is 1 240 would be going 240 divided by 120 is 2 if you say on and on if you'd use 277 Divide it by 120 which gives you 2.31 and so on and so on and hopefully you're getting the point Step five is we have to determine the capacity of the wire being used and there's another table that helps us out with that So what'll be happening here is we'll see that we're putting a certain amount of current on a wire But that wire is also rated for a certain amount of current So we're going to determine are we using the wire to its full capacity because if we're not then we could probably push that wire a little bit further and Then from there once we determine the capacity we go to step six So we determine the distance correction factor which again is in the that table D3 and I'll show you as we go So I just want to take us through a couple examples here So example one how far can you run a number for our 90 copper conductor to feed a load that draws? 50 amps at 240 volts So if we're going through our steps again, is this a known load or is it off a breaker or fuse? We know it's a known load. So step one is 50 amps So what we're going to do here is 50 amps. This is table D3 So if you go to the appendix D and you find table D3, this is looks very similar We're going to run our fingers down over to 50 and then we're using number four So we've got the conductor sizes up here So we're running 50 over to number four and we see that we're connecting at 12.5 that's 12.5 Meters so we're determining that we can run 50 amps on a number four for 12.5 meters without having a negligible volt drop of more than 1% This is remember this is only at 1% and 120 volts so we can we can add some stuff later as we go So step one is 50 amps. We determined step two is 12.5 meters Our step three is because that table is based on 1% and not 3% we can multiply that by 3 So we're going to go 12.5 times 3 is 37.5 meters Step four is when we start taking to account that voltage So we've got 37.5 meters and what we're going to do is multiply that by the voltage factor So 240 divided by 120 is 2 so 37.5 times 2 equals 75 meters Now we're going to dive into that distance correction factor Distance correction factor what we're going to do is we're going to determine what size our cable is good for So we're using I'm using table two right now off out of the CEC So this example you said number four So we've got number four right here and R90 so we see that R90 number four is good up to 95 amps Okay, so it's good for 95 amps, but we're only putting 50 amps on it So if I go 50 divided by 95, I end up with 53 percent We're only using 53 percent of the capacity of that wire Which allows us to be able to push a little further than we normally would be able to How do we determine that well if you turn the page in table D3? You'll see that there's a note note number three and that that gives us this distance correction factor So what we have here is the rated conductor installation temperature So we've got 90 degrees and we had 53 percent Back here, but what we're going to do is there's no 53 percent column So the note tells us to go to the next size up So what we're going to do is go to the 60 degrees So at 90 degrees for the temperature rating of the insulation Then we move along to the 60 degree column and we get a distance correction factor of 1.04 We can push that wire another four percent is basically what that's telling us so what we've got here is We can take that 75 meters and multiply it by 1.04 to get 78 meters And there you go You can run a number for our 90 copper conductor to feed a load that draws 50 amps at 240 For 78 meters for you Americans out there You're just gonna have to multiply that by 3.281 to get the feet So you're looking at a few couple hundred feet there Okay, that's example one example two How far can you run a number six are 90 copper conductor to feed a load that is fed from a 60 amp breaker at 277 volts so again what we're doing here is the load isn't drawing 60 amps is being fed from a 60 amp breaker at 277 volts so step one We don't know the load, but we do know the breaker So we take that at 80 percent because why the code tells us so 8-102 tells us that we use 80% of the size of the circuit breaker or the overcurrent device same idea so we get 48 amps We go down here again. We're using this table to 48 amps There's no 48 amps But we go to 50 next size up and then we run across until we get to number six which in this case is 7.8 meters So we do that 7.8 meters Step three again We're using 3% because remember that table that we were looking at this one rate Let me go back here this one right here is based on 1% so we can multiply that by 3 So we get 23.4 meters Then from 23.4 meters We divide multiply it by the voltage factor in this case We have 277 divided by 120 and that gives us 2.3 So 23.4 times 2.3 equals 54 meters But we're not done yet. We need to check on that distance correction factor So we've got a cable that is rated four. Let's just take a look Here again, we're in table two because we're using copper and we're got more than one So number six is good for 75 amps at the 90 degree column So we're putting 48 amps on a 75 amp rated cable, which means we're using 64 percent of that cable Again, we go turn the page to note number three and we've got this 85 to 90 and we've got 64 percent so we're going to the 70 percent column because there is no 64 percent column So we run that across and we have distance correction factor of one So it's such so negligible that it makes no difference. It's so close to what it's rated is that it's not gonna We can't push it a little bit further So we're just gonna go 54 times 1 which is 54 meters And there you go. That's the two examples I wanted to go through this week Again, if you want to see how wire and pasties figured out you can check up above there There should be a little notification that you can go to last week's video on wire and pasty Next week what I'm gonna do is show you how to use these tables to determine the size of conductor So if you get somebody who comes along and says hey, I've got this hot tub it draws 80 amps I want to put it, you know a hundred feet in backyard You need to determine what size cable that's gonna be you can use these same tables to do that So tables D3 and 8102 are very very important to us out in the field Make sure you click on subscribe and click that bell notification and you can see over there as well I've got last week's video all queued up for you ready to click on it and then I got a recommended video So just a video that I think is useful not necessarily mine. Go ahead and check that out