Why Do We BOND Neutral & Ground in ELECTRICAL SERVICE PANELS?

have you ever wondered why we bond neutrals and grounds together at electrical services let's dig into it [Music] i'm dustin stells with electrician you today we're going to talk about this whole bonding issue so i could do like 15 different videos on grounding i could do like 30 videos on grounding and bonding i'm just gonna tackle this for right now there's a reason why we put our neutrals and our grounds together out at the service and it's really crucial that we do it a certain way and that we don't do it in other places as well so first let's get into what grounding and bonding are so that we can understand bonding a little bit better first when we talk about grounds or grounding that is literally just means we're intentionally taking something and connecting it to earth where in the united states we say grounding other places in the world they call it earthing they don't call it the ground conductor they call it the earth conductor so it's just intentionally taking something from an electrical system and bringing it down to earth and touching it making it continuous with earth now bonding is just taking two things and connecting them to make them one that's really it if we have like a piece of metal and we want this one piece of metal to touch that one that one and that one we want to make them all one essentially one giant piece of metal then we would run bonding jumpers between each one of them so that now they're all connected in some meaningful way that's really it that's a difference between grounding and bonding now why do we bond electrical systems to neutral and ground first of all we need a way to clear a fault if there is a fault condition so how a breaker works typically is as current comes from a transformer down we'll say the black conductor goes through the breaker at the service panel through the black conductor out into the field to a load like a say a light bulb goes through the light bulb comes back on the neutral through that panel and goes back up to where it came from it goes from the source all the way through the system back to the source that is how a circuit works and if too much current happens or something happens all of a sudden that breaker will sense because it's in the middle of a circuit in the middle of a complete loop it'll sense that there's a problem and it will cut the circuit off but we'll say we have a a metal washing machine instead of a light bulb actually let's say we have a light fixture that that same light bulb was uh on before and for some reason the black conductor that is hot that's live right now all of a sudden like breaks off and touches the metal of that fixture what's gonna happen well if we don't have the neutral and the grounds bonded together that ground the metal piece of equipment even though it has a ground wire going to it doesn't have a return path if you follow the ground uh wire you know say we've got our black wire goes through here we've got this piece of metal it comes the piece of metal is around the fixture is attached to the ground wire and the ground wire goes back into the panel and lands on the bus inside of here but how does that metal bus that strap attach to bring current back up to the source to allow that full circuit to flow for there to know that there's a problem to trip that breaker there isn't one so we have to bond the neutral and the ground together so that we can give a return path and complete the circuit to let that breaker know hey there's a problem we need to trip the breaker so ground fault technology arc fault technology any kind of breaker all of it works on the premise that we need a complete circuit for current to flow through it flow through it in large amounts or small amounts or anything but it has to flow and the only way that a circuit is going to flow current is going to flow is if we have a complete circuit from a source all the way back to a source that's the reason that we put the neutral and the ground together is that we have two different kinds of fault conditions we have what is well with really three but for this purposes we're going to talk about two we've got the short circuit which is a type of fault it's a type of problem and that is between a hot and a neutral or it could be a hot and hot but either way with a hot and another hot we have a complete circuit so if a fault happens in a circuit between two different hots we have a complete circuit that that breaker can use to trip and clear the fault if it's a hot and neutral again we have a complete circuit we can trip a fault but with the hot in the ground we have to somehow make the complete circuit and the only way to do that is connecting neutral and ground so that the neutral becomes the path that fault current travels once it hits the panel and goes back up to the power pole that's pretty much it that's as simple as we need to go with it or as more as complex as we need to go with it the problem becomes when people don't know when to bond and where to bond and what size conductors or what things to bond and for this we have to go into 250 in the national electrical code now both 2017 and 2020 are going to be the same on this there's no difference but in 250 part five or it's really roman numeral five so part v uh that's where it talks about bonding and it talks about several different types of things that we have to bond um not just residential service panels but it talks about things like enclosures and raceways it talks about communication systems so if we're bringing like low voltage stuff like cable tv and internet and all of that we have to tie bond those systems to our electrical systems um enclosures and raceways meaning anything we run conductors in like electrical piping then it talks about metal piping again we don't call piping is something you put water in conduit is something you put wire in there's a reason we say bending conduit running conduit raceways we don't say piping but metal piping like gas water things like that are also part of a building system and they're things that a person can get shocked on so we need to be able to clear fault if these things were to ever get energized it also talks about separately derived systems a separately derived system is anything that is deriving electricity or kind of like allowing electricity to move or create electricity for you know like a really bad layman's term but anything that's not utility power so say we have a big transformer and there's all of a sudden now a distinction between the first source of power and the secondary side a new system of power that's a separately derived system that's not being derived from the first part of the system it's a separate system other things like generators or solar arrays you know we got a whole bunch of solar panels you're generating power that is not utility so that separately derived system needs to have grounding and bonding and that is talked about in 250 point uh part five and lastly we have uh lightning protection systems again that's running like huge stakes ground rods in the ground and creating a lightning protection system it needs to be bonded to the regular electrical system just to make sure that they're at the same potential these two different grounding systems are at the same potential so that is something you can read a lot more about 250 part five but really 250.102 is a number that you need to burn and sear into your head because that's really what talks about what we are talking about using bonding jumpers to bond our neutral and our ground together not just bonding two pieces of metal together but more specifically bonding our grounded and our grounding conductors together [Music] and we do this with you know multiple different methods you could have a strap some panels that you buy uh will come with an actual like screw like square d stuff does where it's a green screw that comes with the enclosure and you have to pop it in and screw it in place that bonds the metal can to the ground bus to the neutral bus everything together or if you don't have any of those things then you need to take a conductor and actually make a conductor dependent bond so you create a bonding jumper and it talks about in 250.102 more specifically table 250.102 how to size that conductor what size you need and it's always sized based off of the conductors that are coming in your service entrance conductors your ungrounded conductors or your hots so you open your panel look at the size of your hot conductors and that is what you size your bonding jumper off of because it's really trying to figure out available fault current based off of the conductor size and the resistance of that circuit or the possible reactants not going to get into available fault current because that's a much deeper topic but we don't go off of breaker sizes for this stuff same thing with grounding electrode conductors you know you run a ground bar you run a conductor down to it that is all sized off of the conductor size that's feeding into your service your service entrance conductors the only time that we use a breaker to size a ground is for our equipment grounding conductors those are when you have a home run that's coming out of a panel and it goes out to like a piece of equipment like a wash machine or the plugs in a certain room those grounds those are equipment grounds not grounding electrodes not bonding jumpers those equipment grounds get sized off of breaker sizes we'll get into that later that's a whole different video on its own so again just talking about bonding um the the most important thing for you to know is that we don't want to bond at multiple different locations we don't want every single panel in a house or even just any other panels in a house to have this neutral to ground bond we only want the service panel to have it the reason for that is there's a term called objectionable current an objectionable current is basically current going somewhere that you don't intend it to go when we have a fault that happens in an electrical circuit we want to guarantee that we have built a solid path we know exactly where that current is going to go and we are in control as much as we can be of electricity uh from the fault point back to the source so it responsibly goes where we want it to we don't want a fault to happen and then current just to kind of go like all over the damn place we want it controlled so by doing this we bond in one guaranteed place we make sure that we size the conductor correctly so it can handle any kind of fault currents that happen and we guarantee that we have a path back to the source um and it's only in this one place now objectionable current how that would happen what it would look like say we have like three electrical panels we have our service panel outside we've got a sub panel in our garage maybe another sub panel in like a master bedroom closet or something like that i know just say that that's the case so if we were to bond the ground in the neutral together at every single one of these panels say we have a fault condition at the far end the last panel we have a ground and a neutral bonded together at panel two we have a ground and a neutral bonded together so this means that under any short circuit condition every piece of metal throughout the entire place is going to have current have fault current on it just like the neutral does and it's all going to go through every single piece of equipment throughout the entire house every piece of metal so for a split second everything metallic is going to get energized so we have a path that current is taking through the neutral to get back to the source which is a responsible thing to do but now all that fault current is also taking paths through power supplies through metal pieces of equipment if somebody's holding on to something like there's a potential that they could get shocked if they're touching something metal there's all kinds of different paths that this stuff could go through and you could fry people you could fry people you could fry equipment or hurt people so you don't want that to happen a grounding conductor the equipment grounding conductor the actual bare ground should never have current on it unless you know like a fault happens but you don't want to have current on it and so objectionable current is allowing basically multiple different paths for this current to flow if we have a ground fault we don't want all of that ground fault current to go to ground through the metal pieces of equipment to the source and through all of the neutrals through all of the equipment things that are plugged in power supplies phones everything like that we don't want two different paths for it to take we want to guarantee that when there is a ground fault meaning hot touches ground only ground metal pieces of equipment only that we want it to take the ground conductors and go up to the source but when there is a short circuit nothing to do with the ground wire only black and white or black and red you know your phase conductors or your phase conductor and neutral that's a short circuit you want to make sure that short circuit current goes through the neutral and goes back up into the surface you don't want to have a situation where either one of those faults happens and current takes multiple different paths and just goes like a wrecking ball through every single thing possible it's just kind of haywire and it's going wherever it's wanting that's not a responsible thing to do with some something that's like life-threatening like electricity it's such a dangerous force that we met mess with so having a guaranteed known path that it is going to take is what we do for a living basically all you need to know is at the service panel that is where you bond your neutrals and your grounds go to 250 part 5 specifically 250.102 start looking into how you size those conductors make sure if you're wiring a house that you never put your neutrals and grounds for any of the other panels together only the one at the service if you have instead of your service if you don't have a whole panel uh if you just have a disconnect the main disconnect the first disconnecting means right after the meter that's the point where you put this so again all of this stuff is covered in 250 part 5 or part v and no two that if you're not in residential environments if you're doing other things or you know even if you are if you got like solar panels or generators or stuff that you're putting in just know that anything that's a separately derived system like that also has to be grounded and bonded anytime you're doing anything in a big steel building you need to bond all of the building steel as much of the metal water piping systems the you know all of that stuff together needs to really be connected so that it is all at the same potential you're creating one massive super mega piece of metal rather than having all of these different pieces of metal that you could have one potential on this set of metal and another potential over here and then if you were to touch these two different metal systems you can possibly have a difference of potential which means current could go through you you want to make sure that all pieces of metal are at the same potential that's all i got for today thank you guys so much for all the support thanks for watching all these videos of my mouth blabbing words at you um if you're a supporter of this channel and you're 120 volt member to our 480 volt member dudes thank you so much um for helping me pay my bills and like sponsoring what i do it really really helps um for the you know cost of a cup of coffee a month you're pretty much just helping me keep doing what i'm doing so i really really appreciate it um all my four evil members as promised here's your names okay sorry i'll never do that again um but yeah if you're interested in joining if you haven't joined yet uh there's a little join button down below there's some perks extra stuff you get some top secret things posts that i don't share with anybody else my only fans account no never never that never ever uh no but um that really helps out thank you guys so much make sure you hit subscribe make sure you hit like hit the little notification bell love you crazy [ __ ] see you in the next one discount music and video

Channel: Electrician U

Views: 522,959

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Keywords: electrician, electrical, electricity, dustin stelzer, residential, electrical courses, electrician courses, electrical class, electrician class, electrician school, grounding, bonding, grounding and bonding, what is bonding, what is grounding electricity, why do we need ground wire, ground wire, electrical wiring, ground, earthing, what is earthing, what is grounding, electrical grounding, electrical safety, short circuit, what does neutral do, electrical panel, grounding system

Id: _XM6rXjv0vc

Length: 17min 4sec (1024 seconds)

Published: Mon Apr 05 2021