Multi-Wire Branch Circuits

[Music] now to 10.4 deals with multi weary brain circuits and the rule is on 210 that 4a is all circuits of a multi wire branch circuit must originate from the same piano board I don't know if we have a graphic here multi-wire yes we do so this is a graphic of the definition of a multi wire branch circuit for a single phase and here's what it says multiplied branch circuit is a branch circuit with two or more circuit two or more phase conductors having a voltage between them so right here here's line one line two there's two activity will lie on one line to line three having a voltage between them this is 120 from line one to neutral and 120 from line two to neutral a voltage between them with equal voltage between each phase conductor well between each phase conductor is 240 wouldn't be equal hold as well if I had a third phase then it would be a two B B to C A to C and all those would be this voltage so if it was three base that would be like a Y system so that's a multiply brain circuit Oh so you can use two hots and one neutral now what does that mean that means you just saved a wire instead of running a HANA neutral and a hot and neutral you just save the wire now a little problem with anything right well before you move on if you want to go back to a I think it's a really important point the reason why this rule is relevant and I think specially people that are new if you walk on a job site and you have two panels that are side by side and you've got one space in one paper you know one space in the other panel and you're like oh I could share neutral and I have two spaces and this is and if you're not a service person you may not have seen this a lot my brain is like we talk but I can assure you ryan has seen this many times I know I have it's crazy you go to the panel and and you're like there's only one breaker I have two circuits sharing a neutral where's the other breaker and you're tracing wires and through a conduit and a junction box and up into another panel on and one circuit came out of this panel and a one circuit came out of this panel because both handles are full there was one circuit left in each panel and somebody's very creative and they got the wire from point A to point B again thinking mechanically Wow and it worked Oh so this rule is very relevant ruin and for the new people just to understand this is not a mechanical thing here this is actually a rule in there's reasons why we want to have these coming out of the same panel and Bryant you and I saw this in a house in Florida it had two panels next to each other and they ran circles coming out of one panel and all the neutrals were going back to the other panel yeah my favorite term during class that I stress is do not get 100% a good way to get yourself into trouble and cause extra hazard I saw this in a nursing home and a patient was saying there's something wrong and a breaker tripped it took them three hours to find where the breaker is and wasn't a different floor and there's neutral shading and it's it's a disaster it can cause a lot of nightmare all right well circuit is originating from the same panel we got a lot about rules of multi-wire brain circuit that's two hearts and a neutral tree house and a neutral let me just give you some of the rules they all have to come off of a of a common breaker or a breaker with handle ties and then you have to a group that phase conductors and neutral conductors unless it's obvious and we need to be able to know these three wires or four wires and then go you can watch it go to a breaker not like who knows what's going on yes man I just have to say that ties back to exactly what we were talking about with that neutral being able to bite you if they're not able to be grouped together and you can't isolate them together meaning lockout tagout together where you disconnect all phase conductors at the same time that is the important part about having that group together okay let's talk about multi by branch circuit how does it work out well you have line one going to a TV and you have line two going to a hairdryer and you have they have shared neutral it's called a multi wire branch circuit you have to have them and I like what you just said Jennifer that by having them together on the same breaker and handle ties and you can lock them out and tag them out together now here's what it looks like TB is say 600 watts hair dryer is 1200 watts we can do all the math and so that's the line one to the neutral is 120 line one two to the neutrals 120 in line one the line two is 240 what do i Bryant circuit everything is fine but if for some reason the electrician the panel and the garage takes the wire off and sees a little spark we've done that second time you see it like no first time like Oh interesting well when you had that little spark and you open it up you change it from a multi wire branch circuit as demonstrated here to a series circuit now before we get into the math and before we explain how this all works out you have what Kirk you have up now you have Murphy's Law of a multi-way brain circuit and that Murphy's level multi where brain circuit states then you will always dam it's the most expensive piece of equipment connected to the multi Y brain circuit by the square of the value of the product so TV again yeah there's that square that's math I hate to chop you guys in the math but we're gonna do the math real quick here and you I need a calculation shape at $3,000 TV and you have a thirty dollar piece of equipment and a multi-way branch circuit if there's gonna be a failure it's gonna what the most expensive piece of equipment will sacrifice itself the $3,000 TV will sacrifice itself to protect the $30 cook coffee pot maker or whatever the case might be aside here and it's by the square so three thousand squares compared to 30 square you can tell which one's gonna get destroyed so the TV is not gonna get like a little feud no it's going to destroy the TV now if it had been a $40 something $30 well then of course you just press the reset button it wouldn't have a problem it's right there so that's Murphy's Law with multi right brain circuit let's take a look at the mantel here's what the mat says okay if you know that the TB is 24 ohms because we can do some math we're not to do it and the hairdryer is 12 volts good that was a function of the 600 Watts 120 volt rated we can figure out the resistance if you know the resistances now you have a I'd like to put over here and this graphic here this would be a 24 ohm resistor here and that would be a 12 ohm resistor well if you had 24 ohms here and 12 ohms here you have you have the voltage Kirchhoff's law law that voltage of a series circuits equal to voltage source so you take 240 volts between the two conductors well that means that the TV voltage and the hairdryers voltage will equal to 40 but it's done by the law of proportion so if I showed here 24 ohms and I showed over here 12 ohms that means it's going to be 1 is gonna be 2 parts versus the other or 3 parts you can mathematically it's going to be a hundred and sixty volts on this particular TV versus 80 volts right there the TV will go real fast the people would start moving real quick there for a fraction of a second okay maybe not maybe we just smoke the TV not gonna make the TV go faster okay so that's the problem multi where air what's the advantage I saved the wire you know it's the other advantage of a multi wire brainsick you know who invented the multi by brain circuit I can't who invented it but who probably patent it there's some Edison good back in New York City they ran this 120 volt circuit watch the movie the current Awards they didn't really talk about that and Edison ran 120 volts DC on 25 volt DC and he's doing all this other stuff and then tests like those works for at his sanity cuz I'm an AC Edison I'll get out of here so Tesla goes to the Westinghouse and gets screwed by Westinghouse but that's a whole other story it's idea so they thence that Westinghouse is coming up with alternating current and start from thrown to that and Edison can only go like like feet away from the generating power plant and what they did was they realized you know what if we get another voltage and we go multi-wire a branch circuit if he had 10 amps on line one how many amps is on the neutral align one 10 amps well the other generally been what 10 amps on one I'm loses what 10 but if you get a multi branch circuit and you have one common neutral 10 amps on one 10 amps on the other and gives you how many amps on a neutral zero zero guess what happened to your voltage drop 50% reduction now you can go 50 percent further it's the only like two blocks instead of one block away from the power plants but a listen an improvement is an improvement we're not going to argue so you have reduced voltage drop you have a reduced number of conductors probably a smaller Raceway lower cost everywhere around the bar happen to open that neutral you'll wipe out Murphy's Law square you know whole thing Eric yeah this is a real good reason why you're only allowed to put one neutral under a screw talk about that okay we're gonna talk about that so understanding this concept is the basis for us to the model on so what the heck we've been talking about all to wear a branch circuit it is it is a circuit so come back to Mike Radke multi branch circuits okay shall resonate from the original panel and I'm explaining what a multi branch circuit is and I'm saying the problem the multi Y branch circuit is you can do that here's the code permits it why are we gonna say something I give a practical view of this so what you're saying is with the neutral of the danger I probably don't want to wire an office ability with computers circuits this way or maybe a laboratory very good point right well I think about this in today's world this is different than it was in the seventies when we had incandescent lightbulbs and we had heaters and everything was a linear load right today everything is electronic right it's over you start opening new chose lifting neutrals things are a lot more expensive well I'm just gonna say from a contractor standpoint as much as I appreciate what Ryan's saying you're gonna be running multi-wire brain circuits just happening there's no way you're going into a million plus square foot building in a low bid scenario and you're gonna say I'm gonna pull an extra conductor for every single circuit in this entire building and win a bid against somebody that's not so great idea maybe if you have the option don't do it but that's not going to be the reality let's work with Eric service situation or your service maybe not a big job you know smaller jobs work it is it is a it is a cost factor as a cost factor but there's another really important point if you're dealing and with office furniture with office furnishings and partitions building cubicles yeah everyone that I've seen is wired the bus work inside the office partitions they're all multi wire and saying you have to you have to understand multi-wire brand circuits if you're gonna put in furniture partitions think about it if you follow the code if you do the product according to the code right we're not gonna have a problem so we're done that's what the record multi aware of brain circuits don't have a problem until electricians show up to work on them that's true one guy was working on it real quick when I got out of here even I said well here we're done we're not done okay I want to tell my story guy was working at a Best Buy he opened in the neutral and a Best Buy and it was a multi-way branch circuit him he wiped out $10,000 worth of product the manager of the store was his buddy okay so what they did was they went ahead and they they returned all the products slowly to the different ones and they said it was lightning damage or something like that so he didn't get charged for it so the key here is don't be taking neutrals off of a neutral bus make you put your ant meter on there at least before you do something like that all right let's move on all right all right so now that we know what a multi Y branch circuit is the code requires that you have the ability to simultaneously open up the circuit that means that you can put two single pool breakers with a halo tie or you can use a common trip circuit breaker but this is an example Jennifer you're saying that while you can put a lockout tagout on there the whole key here is that this is a disconnecting means for the multi where branch circuit okay can't not use single pole breakers but you can use individual single pole breakers um what do we got here this one is East multi branch circuit myself it means it's a Miss can I face conduct to the point where the branch sir Corinne eight so can we have that graphic and then we're talking about Singapore maybe Mike here you can show a breaker to single poles in a common trip breakers somewhere in there because we can't tell what this is here so just show the two breakers what we our choices are besides just to text in there you guys okay with that Ryan okay might want to change that NMB to at 12 3 this is 12 3 right here yeah and that's 12 seconds yellow right yeah so that should be 12 3 yeah thank you all right here's a multi wire branch circuit Oh multi Y branch circuit is permitted to supply one utilization equipment so you can take two hearts in a neutral and take a neutral to one piece of equipment I'm not sure whether that's an exception oh the rule was we didn't have the rule here and see price should add the text of the C of the rule the Texas C of the rule says that a multi branch circuit is only permitted is is permitted not prices right on line two only only permitted to design line the neutral line to line loads but there's an exception that you can supply line to line loads what it's gonna be to one piece equipment like a range your dryer or an oven you know multi Y branch circuits grouping we kind of talked about the identification of grouping of neutral conductors and circuits now this is about the grouping and multi wired branch circuits so here's two multi-wire branch circuits my second is it to multiband the phase and neutral conductor multi where branch circuit must be identified or grouped together by cable ties in similar means by 204 B so that was the circuit so you have to group your multi by brain sir right I think something that might make this a little clearer for somebody that's new to this a multi wire branch circuit is just a circuit it's no different than a non multi where branch circuit which is why it's important to group the neutral with the multi wire branch circuit just like you would group a neutral with any other branch circuit so if you look at this example here if I ask the question how many circuits are in this panel the answer is what two two circuits even though two circuits designs a multi wire and one's just a regular branch circuit the perfect moving on there's another hazard of multi web branch circuit let me praise that there's another hat hazard of running a common neutral with multiple circuits see a multi web branch circuit you have to have them either on the same two-pole breaker or a three pole breaker or they have to be single pole breaker camel ties so they're end up inherently being grouped right we don't have a choice there well if you put them on single pole breakers then you can it like you said come on panel one-pound or come off with this bus over here and then come off of the bus down here and so they're not they're not gonna be you can't simultaneously open them so therefore the result is instead of 10 amps what do we have here we have 20 amps on one line and we have 15 amps on the other line the neutral if it were a multi wire branch circuit would be what five eyes but since they're not the current currents not canceling we covered this in electrical fundamentals and how that cancels well now it's gonna be additive I remember distinctly for the first time when I was electrician working looking at a panel and all the wires were white and I noticed one wire was not white like the other white wires but it was like darker when I got to the terminal and then eventually went the white but it kind of like had like a brownish looked at how my guys know I'm talking about yeah you know right okay and I'm looking I'm like walk on my own little world I never thought about once you put an amp meter on that little puppy and find out how many answers drawing because there's a reason that it's brown is because it's heating up if I had like a little scanner and I got thermal imaging I could look at that I can see that one wire is overloaded that means what hey how many times have you guys in here because we all worked as we're all worked as electricians we're trying to balance a panel because the homeowner I remember in the 70s they had like a hundred amp panel or a 60 amp panel and you want to change the whole service there's no need that you put a net meter on line on line two and you find out line ones drawing 60 amps on line two is drawing 20 amps you're like you know what let me just kind of move the circuits around here and make it lace a 30 and 30 and say the person our whole service trains at least for right now help well guess what I never knew we didn't that had Hamilton comet handle tires on circuits we did not anything about grouping of the neutral conductors I just took a wire off of one phase took it off of here and I just moved him all around it to like okay perfect didn't think about other words you were fixing one problem and creating another one yeah I was I was preventing there was no problem but I was creating a problem right because I'm like I got you know hi Jennifer what happened what did I do [Laughter] [Music] [Laughter] so here's the problem with the multi variant circuits is that somebody or that doesn't understand a multi Y brain circuits and hazards and that's why we have the grouping and that's what we have simultaneously disconnecting means I try to prevent it Brian it's okay and like Brian is saying listen we're putting in multi wire branch circuits but if you want to pay for me to put bigger pipes more wires and pay for more copper like if you was a good idea if you work Eric unlimited budget well then it's popular idea talking about you what is your feeling do you guys allow multi web branch circuits especially yes yes we do our engineering standards used to dis allowable to our branch circuits but that was based on I Triple E emerald book which is the sentence called sensitive electronic components so with multi wire branch circuits if you have laboratory extensive laboratory equipment say on phase a but you have something on phase B switching on and off you can cause voltage differences and so we used to have a blanket statement saying no multi-wire since then that statements been changed and it said we don't use multi wire in laboratories of sensitive equipment but for pretty much everything else we allow it the practical thing is let's let's be practical here we don't have to be like perfect [Music]

[Music] now to 10.4 deals with multi weary brain circuits and the rule is on 210 that 4a is all circuits of a multi wire branch circuit must originate from the same piano board I don&#39;t know if we have a graphic here multi-wire yes we do so this is a graphic of the definition of a multi wire branch circuit for a single phase and here&#39;s what it says multiplied branch circuit is a branch circuit with two or more circuit two or more phase conductors having a voltage between them so right here here&#39;s line one line two there&#39;s two activity will lie on one line to line three having a voltage between them this is 120 from line one to neutral and 120 from line two to neutral a voltage between them with equal voltage between each phase conductor well between each phase conductor is 240 wouldn&#39;t be equal hold as well if I had a third phase then it would be a two B B to C A to C and all those would be this voltage so if it was three base that would be like a Y system so that&#39;s a multiply brain circuit Oh so you can use two hots and one neutral now what does that mean that means you just saved a wire instead of running a HANA neutral and a hot and neutral you just save the wire now a little problem with anything right well before you move on if you want to go back to a I think it&#39;s a really important point the reason why this rule is relevant and I think specially people that are new if you walk on a job site and you have two panels that are side by side and you&#39;ve got one space in one paper you know one space in the other panel and you&#39;re like oh I could share neutral and I have two spaces and this is and if you&#39;re not a service person you may not have seen this a lot my brain is like we talk but I can assure you ryan has seen this many times I know I have it&#39;s crazy you go to the panel and and you&#39;re like there&#39;s only one breaker I have two circuits sharing a neutral where&#39;s the other breaker and you&#39;re tracing wires and through a conduit and a junction box and up into another panel on and one circuit came out of this panel and a one circuit came out of this panel because both handles are full there was one circuit left in each panel and somebody&#39;s very creative and they got the wire from point A to point B again thinking mechanically Wow and it worked Oh so this rule is very relevant ruin and for the new people just to understand this is not a mechanical thing here this is actually a rule in there&#39;s reasons why we want to have these coming out of the same panel and Bryant you and I saw this in a house in Florida it had two panels next to each other and they ran circles coming out of one panel and all the neutrals were going back to the other panel yeah my favorite term during class that I stress is do not get 100% a good way to get yourself into trouble and cause extra hazard I saw this in a nursing home and a patient was saying there&#39;s something wrong and a breaker tripped it took them three hours to find where the breaker is and wasn&#39;t a different floor and there&#39;s neutral shading and it&#39;s it&#39;s a disaster it can cause a lot of nightmare all right well circuit is originating from the same panel we got a lot about rules of multi-wire brain circuit that&#39;s two hearts and a neutral tree house and a neutral let me just give you some of the rules they all have to come off of a of a common breaker or a breaker with handle ties and then you have to a group that phase conductors and neutral conductors unless it&#39;s obvious and we need to be able to know these three wires or four wires and then go you can watch it go to a breaker not like who knows what&#39;s going on yes man I just have to say that ties back to exactly what we were talking about with that neutral being able to bite you if they&#39;re not able to be grouped together and you can&#39;t isolate them together meaning lockout tagout together where you disconnect all phase conductors at the same time that is the important part about having that group together okay let&#39;s talk about multi by branch circuit how does it work out well you have line one going to a TV and you have line two going to a hairdryer and you have they have shared neutral it&#39;s called a multi wire branch circuit you have to have them and I like what you just said Jennifer that by having them together on the same breaker and handle ties and you can lock them out and tag them out together now here&#39;s what it looks like TB is say 600 watts hair dryer is 1200 watts we can do all the math and so that&#39;s the line one to the neutral is 120 line one two to the neutrals 120 in line one the line two is 240 what do i Bryant circuit everything is fine but if for some reason the electrician the panel and the garage takes the wire off and sees a little spark we&#39;ve done that second time you see it like no first time like Oh interesting well when you had that little spark and you open it up you change it from a multi wire branch circuit as demonstrated here to a series circuit now before we get into the math and before we explain how this all works out you have what Kirk you have up now you have Murphy&#39;s Law of a multi-way brain circuit and that Murphy&#39;s level multi where brain circuit states then you will always dam it&#39;s the most expensive piece of equipment connected to the multi Y brain circuit by the square of the value of the product so TV again yeah there&#39;s that square that&#39;s math I hate to chop you guys in the math but we&#39;re gonna do the math real quick here and you I need a calculation shape at $3,000 TV and you have a thirty dollar piece of equipment and a multi-way branch circuit if there&#39;s gonna be a failure it&#39;s gonna what the most expensive piece of equipment will sacrifice itself the $3,000 TV will sacrifice itself to protect the $30 cook coffee pot maker or whatever the case might be aside here and it&#39;s by the square so three thousand squares compared to 30 square you can tell which one&#39;s gonna get destroyed so the TV is not gonna get like a little feud no it&#39;s going to destroy the TV now if it had been a $40 something $30 well then of course you just press the reset button it wouldn&#39;t have a problem it&#39;s right there so that&#39;s Murphy&#39;s Law with multi right brain circuit let&#39;s take a look at the mantel here&#39;s what the mat says okay if you know that the TB is 24 ohms because we can do some math we&#39;re not to do it and the hairdryer is 12 volts good that was a function of the 600 Watts 120 volt rated we can figure out the resistance if you know the resistances now you have a I&#39;d like to put over here and this graphic here this would be a 24 ohm resistor here and that would be a 12 ohm resistor well if you had 24 ohms here and 12 ohms here you have you have the voltage Kirchhoff&#39;s law law that voltage of a series circuits equal to voltage source so you take 240 volts between the two conductors well that means that the TV voltage and the hairdryers voltage will equal to 40 but it&#39;s done by the law of proportion so if I showed here 24 ohms and I showed over here 12 ohms that means it&#39;s going to be 1 is gonna be 2 parts versus the other or 3 parts you can mathematically it&#39;s going to be a hundred and sixty volts on this particular TV versus 80 volts right there the TV will go real fast the people would start moving real quick there for a fraction of a second okay maybe not maybe we just smoke the TV not gonna make the TV go faster okay so that&#39;s the problem multi where air what&#39;s the advantage I saved the wire you know it&#39;s the other advantage of a multi wire brainsick you know who invented the multi by brain circuit I can&#39;t who invented it but who probably patent it there&#39;s some Edison good back in New York City they ran this 120 volt circuit watch the movie the current Awards they didn&#39;t really talk about that and Edison ran 120 volts DC on 25 volt DC and he&#39;s doing all this other stuff and then tests like those works for at his sanity cuz I&#39;m an AC Edison I&#39;ll get out of here so Tesla goes to the Westinghouse and gets screwed by Westinghouse but that&#39;s a whole other story it&#39;s idea so they thence that Westinghouse is coming up with alternating current and start from thrown to that and Edison can only go like like feet away from the generating power plant and what they did was they realized you know what if we get another voltage and we go multi-wire a branch circuit if he had 10 amps on line one how many amps is on the neutral align one 10 amps well the other generally been what 10 amps on one I&#39;m loses what 10 but if you get a multi branch circuit and you have one common neutral 10 amps on one 10 amps on the other and gives you how many amps on a neutral zero zero guess what happened to your voltage drop 50% reduction now you can go 50 percent further it&#39;s the only like two blocks instead of one block away from the power plants but a listen an improvement is an improvement we&#39;re not going to argue so you have reduced voltage drop you have a reduced number of conductors probably a smaller Raceway lower cost everywhere around the bar happen to open that neutral you&#39;ll wipe out Murphy&#39;s Law square you know whole thing Eric yeah this is a real good reason why you&#39;re only allowed to put one neutral under a screw talk about that okay we&#39;re gonna talk about that so understanding this concept is the basis for us to the model on so what the heck we&#39;ve been talking about all to wear a branch circuit it is it is a circuit so come back to Mike Radke multi branch circuits okay shall resonate from the original panel and I&#39;m explaining what a multi branch circuit is and I&#39;m saying the problem the multi Y branch circuit is you can do that here&#39;s the code permits it why are we gonna say something I give a practical view of this so what you&#39;re saying is with the neutral of the danger I probably don&#39;t want to wire an office ability with computers circuits this way or maybe a laboratory very good point right well I think about this in today&#39;s world this is different than it was in the seventies when we had incandescent lightbulbs and we had heaters and everything was a linear load right today everything is electronic right it&#39;s over you start opening new chose lifting neutrals things are a lot more expensive well I&#39;m just gonna say from a contractor standpoint as much as I appreciate what Ryan&#39;s saying you&#39;re gonna be running multi-wire brain circuits just happening there&#39;s no way you&#39;re going into a million plus square foot building in a low bid scenario and you&#39;re gonna say I&#39;m gonna pull an extra conductor for every single circuit in this entire building and win a bid against somebody that&#39;s not so great idea maybe if you have the option don&#39;t do it but that&#39;s not going to be the reality let&#39;s work with Eric service situation or your service maybe not a big job you know smaller jobs work it is it is a it is a cost factor as a cost factor but there&#39;s another really important point if you&#39;re dealing and with office furniture with office furnishings and partitions building cubicles yeah everyone that I&#39;ve seen is wired the bus work inside the office partitions they&#39;re all multi wire and saying you have to you have to understand multi-wire brand circuits if you&#39;re gonna put in furniture partitions think about it if you follow the code if you do the product according to the code right we&#39;re not gonna have a problem so we&#39;re done that&#39;s what the record multi aware of brain circuits don&#39;t have a problem until electricians show up to work on them that&#39;s true one guy was working on it real quick when I got out of here even I said well here we&#39;re done we&#39;re not done okay I want to tell my story guy was working at a Best Buy he opened in the neutral and a Best Buy and it was a multi-way branch circuit him he wiped out $10,000 worth of product the manager of the store was his buddy okay so what they did was they went ahead and they they returned all the products slowly to the different ones and they said it was lightning damage or something like that so he didn&#39;t get charged for it so the key here is don&#39;t be taking neutrals off of a neutral bus make you put your ant meter on there at least before you do something like that all right let&#39;s move on all right all right so now that we know what a multi Y branch circuit is the code requires that you have the ability to simultaneously open up the circuit that means that you can put two single pool breakers with a halo tie or you can use a common trip circuit breaker but this is an example Jennifer you&#39;re saying that while you can put a lockout tagout on there the whole key here is that this is a disconnecting means for the multi where branch circuit okay can&#39;t not use single pole breakers but you can use individual single pole breakers um what do we got here this one is East multi branch circuit myself it means it&#39;s a Miss can I face conduct to the point where the branch sir Corinne eight so can we have that graphic and then we&#39;re talking about Singapore maybe Mike here you can show a breaker to single poles in a common trip breakers somewhere in there because we can&#39;t tell what this is here so just show the two breakers what we our choices are besides just to text in there you guys okay with that Ryan okay might want to change that NMB to at 12 3 this is 12 3 right here yeah and that&#39;s 12 seconds yellow right yeah so that should be 12 3 yeah thank you all right here&#39;s a multi wire branch circuit Oh multi Y branch circuit is permitted to supply one utilization equipment so you can take two hearts in a neutral and take a neutral to one piece of equipment I&#39;m not sure whether that&#39;s an exception oh the rule was we didn&#39;t have the rule here and see price should add the text of the C of the rule the Texas C of the rule says that a multi branch circuit is only permitted is is permitted not prices right on line two only only permitted to design line the neutral line to line loads but there&#39;s an exception that you can supply line to line loads what it&#39;s gonna be to one piece equipment like a range your dryer or an oven you know multi Y branch circuits grouping we kind of talked about the identification of grouping of neutral conductors and circuits now this is about the grouping and multi wired branch circuits so here&#39;s two multi-wire branch circuits my second is it to multiband the phase and neutral conductor multi where branch circuit must be identified or grouped together by cable ties in similar means by 204 B so that was the circuit so you have to group your multi by brain sir right I think something that might make this a little clearer for somebody that&#39;s new to this a multi wire branch circuit is just a circuit it&#39;s no different than a non multi where branch circuit which is why it&#39;s important to group the neutral with the multi wire branch circuit just like you would group a neutral with any other branch circuit so if you look at this example here if I ask the question how many circuits are in this panel the answer is what two two circuits even though two circuits designs a multi wire and one&#39;s just a regular branch circuit the perfect moving on there&#39;s another hazard of multi web branch circuit let me praise that there&#39;s another hat hazard of running a common neutral with multiple circuits see a multi web branch circuit you have to have them either on the same two-pole breaker or a three pole breaker or they have to be single pole breaker camel ties so they&#39;re end up inherently being grouped right we don&#39;t have a choice there well if you put them on single pole breakers then you can it like you said come on panel one-pound or come off with this bus over here and then come off of the bus down here and so they&#39;re not they&#39;re not gonna be you can&#39;t simultaneously open them so therefore the result is instead of 10 amps what do we have here we have 20 amps on one line and we have 15 amps on the other line the neutral if it were a multi wire branch circuit would be what five eyes but since they&#39;re not the current currents not canceling we covered this in electrical fundamentals and how that cancels well now it&#39;s gonna be additive I remember distinctly for the first time when I was electrician working looking at a panel and all the wires were white and I noticed one wire was not white like the other white wires but it was like darker when I got to the terminal and then eventually went the white but it kind of like had like a brownish looked at how my guys know I&#39;m talking about yeah you know right okay and I&#39;m looking I&#39;m like walk on my own little world I never thought about once you put an amp meter on that little puppy and find out how many answers drawing because there&#39;s a reason that it&#39;s brown is because it&#39;s heating up if I had like a little scanner and I got thermal imaging I could look at that I can see that one wire is overloaded that means what hey how many times have you guys in here because we all worked as we&#39;re all worked as electricians we&#39;re trying to balance a panel because the homeowner I remember in the 70s they had like a hundred amp panel or a 60 amp panel and you want to change the whole service there&#39;s no need that you put a net meter on line on line two and you find out line ones drawing 60 amps on line two is drawing 20 amps you&#39;re like you know what let me just kind of move the circuits around here and make it lace a 30 and 30 and say the person our whole service trains at least for right now help well guess what I never knew we didn&#39;t that had Hamilton comet handle tires on circuits we did not anything about grouping of the neutral conductors I just took a wire off of one phase took it off of here and I just moved him all around it to like okay perfect didn&#39;t think about other words you were fixing one problem and creating another one yeah I was I was preventing there was no problem but I was creating a problem right because I&#39;m like I got you know hi Jennifer what happened what did I do [Laughter] [Music] [Laughter] so here&#39;s the problem with the multi variant circuits is that somebody or that doesn&#39;t understand a multi Y brain circuits and hazards and that&#39;s why we have the grouping and that&#39;s what we have simultaneously disconnecting means I try to prevent it Brian it&#39;s okay and like Brian is saying listen we&#39;re putting in multi wire branch circuits but if you want to pay for me to put bigger pipes more wires and pay for more copper like if you was a good idea if you work Eric unlimited budget well then it&#39;s popular idea talking about you what is your feeling do you guys allow multi web branch circuits especially yes yes we do our engineering standards used to dis allowable to our branch circuits but that was based on I Triple E emerald book which is the sentence called sensitive electronic components so with multi wire branch circuits if you have laboratory extensive laboratory equipment say on phase a but you have something on phase B switching on and off you can cause voltage differences and so we used to have a blanket statement saying no multi-wire since then that statements been changed and it said we don&#39;t use multi wire in laboratories of sensitive equipment but for pretty much everything else we allow it the practical thing is let&#39;s let&#39;s be practical here we don&#39;t have to be like perfect [Music]

Transcript for:Multi-Wire Branch Circuits

Transcript for:
Multi-Wire Branch Circuits