Why Do We Bond at the Service Panel and Not a Subpanel?

[@johnpetruna8888]

That is the best explanation of this concept/rule I have ever seen. And I'm almost a boomer!

[@russashworth1340]

your use of the term neutral jumps between code and slang in the trade. In Canada the the use of the word neutral is well defined. As far as bonding a neutral in a building not part of the "service entrance " is due to RF energy. Go back too school. HR Ashworth. 309 A ,309 D & Ontario masters. Inter provincial

[@tiggeroush]

@@russashworth1340 it is interesting, the differences between codes of different countries. The 2020 NEC does not define neutral but does define Neutral Conductor as the conductor connected to the neutral point of a system that is intended to carry current under normal conditions. It defines Neutral Point as the common point on a wye-connection in a polyphase system or midpoint on a single-phase, 3 wire system, or midpoint of a single-phase portion of a 3-phase delta system, or a midpoint of a 3-wire, direct-current system. It defines Grounded Conductor as a system or circuit conductor that is intentionally grounded.

[@stevenriggs9631]

@@russashworth1340 .. maybe Mm T5f fr f rv 6

[@raisingcaine5480]

Careful, or BOOM, BOOM, out go the lights!

[@rjfontenotiii]

I believe it is you that needs to go back "too" school.

[@turmoilfab]

I’m not even an electrician but this is now the only guy I go to to get an explanation I can try to grasp. Great job!

[@john65645]

I'm a retired IBEW inside wireman. You do a very good job of explaining this. There's so much information that a good electrician needs to know to work in the field and that's why continued training is a must. It's good to be retired.

[@lor332]

Local 38. Congrats

[@charu002]

424 here as second year apprentice. i agree

[@seanb2604]

Local 26 👍

[@ricksta831]

Local 234 ... ibew

[@neilbarrow666]

Hey Dustin. I'm an electrician in the Bahamas and this is the best explanation I've ever heard explaining this. Now I will use this video as a teaching tool when I get in an argument pertaining to bonding. Thanks.

[@rg8110]

Which part of the 🇧🇸???

[@tiggeroush]

Just out of curiosity what electric code is used in the Bahamas?

[@neilbarrow8110]

@@rg8110 Nassau

[@neilbarrow8110]

@@tiggeroush Canadian Electrical Code

[@ottoroth3066]

Neil Barrow.....does the NEC we have here in the states apply in the Bahamas.....just curious!

[@robertdabicci317]

Been wanting an explanation for the multiple sub panel bonding issue and this is the best information I have found. I knew you didn't want to bond except at the main panel but didn't understand why until now. Thank you for a great video. Bob

[@nobadmojo70]

Man, you've really elevated your teaching game, which is really saying something, your older videos are really good. This new generation of Electrician U is outstanding! It's very well organized, demonstrated, explained and marketed. Thank you again for all of your efforts and pushing through the challenges. Keep up the excellent work!

[@lawbulb]

As a layperson, I didn’t understand any of this until I saw your presentation. I can’t possibly explain it to someone else like you did, but I really get a feel for how this stuff works now. Fascinating stuff!

[@rossroberts3212]

This is the only video I have found that actually helps build the concept in your mind. Very nice! The only thing missing is the explanation of "Service Panel" being the first junction past the meter or equivalent as the place needing neutral to ground bonding, be it a service disconnect switch or main breaker panel inside of the structure. Bravo!

[@allanamen6267]

Hi Iam an electrician from Papua New Guinea and retired. Found you explanation very interesting and simple. Good on you.

[@williammoyer9063]

Kudo's from a retired Union Electrician on being able to break it down so well. Keeping the grounds and neutrals separate greatly helps when trouble shooting, GFCI issues especially.

[@johnkruton9708]

Your illustrations and explanations are the excellent educational visual along with Mike Holt’s very technical history and explanation about bonding. Eg: Factory motors, DC pulse (lightning) literally taking 120V line and putting to earth and measuring the current and seeing if a breaker will trip (it doesn’t)….your visuals complete the brain circuit!!!

[@emoryjiles6411]

This fellow brought up some key points about sub-panel wiring I never really considered. He is a gifted teacher. I’ll be tuning in for more. I’m a humbled 30+ year electrical engineer.

[@aaaaaaaaaaaaaa1674]

I don't think evey8ne knows how much of a help you are!! Your such an amazing content creator appreciate your time man !!

[@brianc9210]

Best explanation I have seen. Checked my garage panel and it was incorrect. I fixed it. Thank you.

[@spruce_goose5169]

16:18 I believe objectionable current is more in reference to neutral current (i.e. normal operating conditions) rather than ground fault. In other words, the issue is less ground fault current traveling on a neutral conductor and more normal operating current that should be solely on the neutral traveling on the ground (EGC).

[@toddtaylor7136]

This is correct. You don't want the normal neutral current flowing through the ground wires as they are not sized or intended for this purpose. The rest of the video was spot on. Nice job Electrician U

[@traditionaltools5080]

Absolutely right. You see it in three wire, three phase systems when people want to be able to get both line and phase voltages. So they use ground as a voltage reference. Bad idea.

[@brianbray5397]

@@toddtaylor7136 Yes, It also means that you have return current on anything bonded, such as the panel itself.

[@plehmann72]

With no bonding between neutral and ground, you don't have earth fault current on neutrals , you just have no path to source neutral? Also, current isn't the direct danger, it's the voltage which can lead to defibrillation when your body's resistance allows current to flow through you and affect the hearts rhythm.

[@spruce_goose5169]

@@plehmann72 having trouble understanding your question (or is it a statement?). If you had zero bonding anywhere in the system (which is not what we want), then yes, a ground fault would have to travel to source neutral (transformer) via the ground rod connections. Definitely not what we want and may not trip the breaker. That's why we bond. In one place. Bonding in multiple places simply means more system components will carry current when they should not be, potentially causing a dangerous situation.

[@michaeldunn9018]

1st year apprentice here, thanks for taking the time to make these easy to understand and simplified videos Dustin!

[@memozzy22]

I haven't been watching lately but I'm so glad you've grown your channel so much!

[@yyourmoma]

If you understand what grounding actually is and why and what its really doing then you would never need this video. What a great topic! More people need to understand grounding!

[@raymond3722]

Your topics always filled with clarity at its best,and your demonstration is on Q.

[@jkitchens71]

Holy crap...now I know where to come to understand the why's ! I bonded my sub panel at the main panel...didn't know why, I just knew I needed to. Excellent explanation! Thank you.

[@jeffgreen7897]

I enjoy your videos. I am from Colorado and I just hit 40 years in the trade. I love what I do and I love learning I am a service electrician after being on new construction projects for 20 years when I first got in the trade and I have learned so much. Troubleshooting is the best class ever.

[@s.mendez7160]

Most excellent explanation, especially since it was done in color for us visual learners. Thank you for your teachings.

[@BrandonCarrillo-p5w]

I do a lot of diy wiring, I've always followed this as a rule but never fully understood why. This is the best visual explanation anyone could ask for, Thank you so much!

[@elBusDriverKC]

Great topic. I actually already knew all of this, but wanted to make sure there wasn't any gaps I needed filled in. You do a good job of explaining! On that note, please do a video on portable gas generators in relation to grounding, neutral, back feed dangers etc...

[@dwightdhansen]

Same here. The Army cable installer course actually did a pretty good job of explaining this stuff.

[@kennyhammond7087]

I’m sure you do bus driver man.

[@tomygun1585]

Thanks for the video. Too many don't understand that there's a difference between grounding and bonding. And remember, every wire is a fusible link. Cheers.

[@HarrisonFrith-cr4ie]

Something that is often not mentioned is that if neutral and ground are bonded, a broken neutral at any point before the bond will cause all grounds downstream of the bond to develop a potential of 120V relative to earth, as they are seeking to return to the neutral via ground having lost their neutral. This was touched on in the video but it warrants further explanation as to the theory. Only doing the bond in one place minimizes the amount of conductor that would create this condition if it were broken. If the service neutral breaks it'd be very obvious. But if a feeder neutral breaks to a subpanel feeding your garage, you might not notice until you touch it later and get a shock from the grounded components that are now 120V to earth!

[@kellyschlumberger1030]

If just a neutral breaks you still have hots. The earth ground would trip the breaker. Since only the hots run thru breakers (neutrals don't) earth ground is the only thing to save your life. This feels like time travel. Maybe the professional will read this and help us all?

[@HarrisonFrith-cr4ie]

@@kellyschlumberger1030 The neutral breakage at a point where neutral and ground are bonded will cause the ground to develop 120V potential, because the power wants to return to source via the ground bond as it cannot get through the broken neutral so travels through the bond to the ground instead. separated grounds/neutrals don't have this problem, so that's why they are always separated whenever possible

[@godfaithfamilythenme]

I’m getting back in the trade after 17 years, these videos have helped me a lot. Thank you very much

[@chrisshort8821]

Fantastic video , I’ve learned so much since subscribing to your channel. Very much appreciated for your time and effort you put into theses videos. I’ve only been in the electrical field for the past 6 years and other then being told that the bonding jumper has to be removed in the sub panel through practice, I never had a clear understanding of the reason. This video provided a perfect explanation , thanks again!

[@swayed3015]

Thank you for explaining this..I ran across this yesterday while installing a sub panel. The neutral and ground were set up to be bonded but we had to change it! As an Apprentice I appreciate these videos!! 👌🏼

[@scottgarner2701]

Great video - I really like how you explain things - one very important detail I would like to add. Imagine a 50-amp GFCI circuit breaker installed in the main panel where the ground-neutral bond can (should) be found. Now imagine a sub panel supplied by that 50 amp beaker, except that there also has a ground-neutral bond in the sub panel. The 50 amp GFCI breaker will always think there is a ground fault and trip. So no GFCI or similar safety devices will work if there is a downstream ground-neutral bond. Thanks for listening and good luck!

[@NoName-OG1]

After having watched this, I have two comments. First connection of a neutral to ground anywhere outside of the main electrical service, is also considered a “ground fault“, not just hot conductors. It is technically any current carrying conductor with a connection in advertently to ground. If you have not already done an episode on how a GFCI works, it measures current going out, and then returning, and if there is a significant difference, it will trip. Indicating that there is current traveling on another path. The other comment, is somewhat mind blowing if you wrap your head around it. The neutral at a transformer it’s always going to be a current current conductor. Meaning that it’s always going to be varying at potential. When grounding it, you are not necessarily bringing the neutral conductor to the potential of earth, you are bringing the potential of the earth in the general area, to its potential of the neutral. Bringing them both closer together. The neutral, a.k.a. the grounded conductor, and your electrons of an area are brought to the same potential. This is yet another reason not to bond ground and neutral in subpanels in exterior buildings. Like a detached garage. And this is why metal piping systems are also brought to the same potential in each structure. Having a parallel current throughground, would have a voltage offset from that of the electrodes of the building. And while that may be minor, that still represents a hazard.

[@donphillips5957]

Question. An exterior panel with a main breaker in a separate box above it. Is it OK to have the ground to earth connected to both? Neutral is bonded only in the main panel.

[@NoName-OG1]

@@donphillips5957 your main disconnecting means and/or meter enclosure is the only place to which the MBJ main bonding jumper is to connect neutral to ground…. This is also where your electrodes (connection to earth would connect in the United States) - to the neutral. These are what grounds the grounded conductor (aka neutral). Grounds from any other feeder or branch would follow the circuit paths along the same circuit paths as the current carrying conductors. So - other than the case of separate structures electrodes should connect to the main enclosure. And to the sun panel only in cases of separate structures. Like if you had a detached garage or pool house or shed that had a panel - the grounding electrodes should go to the panel serving that building. But not neutral to ground connection in that separate building. (At least since about 96)

[@Yo-Yo888AA]

@@NoName-OG1 I have a detached garage with its own panel (100A main breaker, 1- 30A 220, and 4 15A 110 breakers) I have a 3 wire, direct burial cable supplying 240v from my main 200A service panel. The garage panel is grounded to earth through its own ground rod. Should my ground and neutral be bonded in this panel?

[@NoName-OG1]

@@Yo-Yo888AA up until about 1996 it could be. And after 2008, it was definitely illegal… After that all new installations would have grounding conductor with the feeder from the the garage from the main panel to the panel at the garage AND ALSO have a ground rod at the garage. But no neutral bond at at any subpanel. Even if it’s a separate structure after 2008. (Post ‘96 you would also have a grounding conductor for ranges and dryers be separate) The philosophy of grounding and bonding changed in that year 1996, and the years following continued to catch all the places in the code that missed being updated by 2008. To separate “fault current” and “unbalanced load current” into separate and distinct paths. So as not to have “Objectionable current” Each separate structure is required to have an “grounding electrode system” for that structure. Rods, concrete encased electrodes, and pipe systems bond to the electrode system. Those are bonded to the panel serving the structure. “Grounding conductors” are connected to that electrode system - to include those between structures. As branch equipment grounding conductors and feeder grounding conductors. Branch and feeder - Neutral conductors (AKA GROUNDED CIRCUIT CONDUCTORS) carry unbalanced load current, and as such have different electrical potential depending on where they are in the system. And should not have parallel paths on equipment cases or exposed metal boxes or anything else. This would be “objectionable current” And if bonded in multiple places would make the ground-ing conductors a parallel path for the current. Or conversely the neutral a parallel for fault current. “Objectionable” So the decision was made to make them completely separate apart from a single point at the main/meter panels. So that only fault current is on the grounding conductors, and only unbalanced load current is only on the neutral. So if your garage was built prior to 2008 it’s ok for the thinking of the time. And you may even lack a grounding conductor between structures and you would have the bond neutral to ground to have any ground fault path at all. And most inspectors would have you correct it if there were new construction in the garage for a new panel. If it was after 2008, it’s a code violation to bond neutral to ground in a separate structure. And a violation to not have a grounding conductor with the feeder to a separate structure. Hope this makes sense of the how and why…. If not look for “Mike Holt grounding - separate structure - fault current” and you’ll likely find an image depicting this with an explanation of reasoning. Or search “objectionable current separate structure NEC” or 250.32 in your code book.

[@Yo-Yo888AA]

@@NoName-OG1 so when you say grounding conductor feeder from main panel to garage your basically meaning a 4 wire set up? 2 hots a neutral AND a ground? Plus also need the ground rod which i have? Btw it was built before 96 and have had no issues and plan no other construction. But if there is a better/safer way ...

[@texaslookout5382]

Finally someone who knows how to get the point across. Many Thanks

[@45-308]

I like you videos and want to point something out regarding this topic. Perhaps you mentioned it but I didn't catch it. You seamed to focus on fault conditions when speaking about objectionable current. If you bond in a sub panel you with have objectionable current on the EGC in normal conditions because it will be in parallel with the neutral (grounded conductor) back to the main panel.

[@spruce_goose5169]

Exactly. I'm pretty sure what you speak of is generally what 'objectionable current' refers to: current on the EGC under normal operating conditions.

[@stevenlowery7153]

You are correct about the parallel currents running on both the neutral and ground wires. This will also cause ground fault breakers to falsely trigger because it detects a current difference between the hot and neutral wires.

[@jief85l42]

Because the transformer is connected to ground, the current has a path (through earth) to loop to the source. In some country, there is absolutely NO connection between ground at neutral. And breakers still trip. But of course that only works if the soil has very low resistance, which maybe not the case everywhere in the US ?

[@adityaprasad465]

Awesome. Just to complete the explanation for anyone who didn't get it: if we bond ground to neutral at a subpanel and carry current through that parallel path, then there may not be enough current through the breaker path to trip the breaker. Current is split amongst the parallel paths.

[@kevinb5717]

I am so glad I found your channel. I'm sure your channel will hit 500k this year. You have an awesome way of educating us and thanks for taking the time to do it.

[@pibblesnbits]

This comment aged well.

[@cscrivani]

THANK YOU. This finally explains to me, the non-electrician but technical guy, what the neutral really does, and why the ground is bonded at the panel to neutral. Also explains why 'boot leg' grounds are bad and dangerous. I live in an old house and do look for them if I pop off an outlet for any reason.

[@ElectricRob]

Nice explanation and your sketches really help to visualize the current flow thru the distribution system. One thing I'd add is that your examples mainly deal with fault conditions (short circuit and ground fault), but even during normal operation on for example a 120V load, if ground and neutral are connected at two ends, you just made the neutral a parallel set of conductors (neutral and ground in parallel), so current flows on both wires, and as you noted, we normally do not want current flowing on the ground wire (except in ground fault situations).

[@fredsasse9973]

Yes! Current does not only take the path of least resistance, it takes ALL paths. Granted, the current flowing through the path of least resistance will be higher than the inverse proportion of the level of resistance of the alternate path(s).

[@bnasty267]

The concept that is difficult for most to grasp is that electricity will always take ALL paths back to the source, in proportion to the impedance. The easiest way to show this is that some current exists on your bond to the water line (go ahead and check with a clamp ammeter) even though there is a functional neutral wire back to the secondary on the transformer for your house. That wire carries most of the current, because its impedance is the lowest, but the ground (literal dirt) also carries some. This is expected here (the water line), but isn't for other grounding paths like from a subpanel.

[@Nuttypro-f]

Whoever doesn’t get that needs to go back to pushin paper

[@hyenakilla31]

BRO! I understand now!!! I have been struggling with this for about 3 years on why not to bond subs. I watched a good video about six months ago. it was good but did not, "complete the circuit in my brain". 15:30 is where the understanding came to me bro. Thank you.

[@clermontglock]

Question: Home has 400 amp service with a 200 amp main service panel (bonded) and a 200 amp sub panel service (NOT bonded). An electrician recently installed two Eaton CHSPT2ULTRA surge protectors, one in main service panel and one in sub panel service. Wiring for main service is per the surge protector installation instructions, Red/Black to 50 amp breaker, White to neutral bar and Green to ground bar. The wiring for sub panel is Red/Black to 50 amp breaker, and BOTH the White and Ground to ground bar. Also per surge protector installation instructions regarding LED's, it says "Protected when both lit". Both LED's are lit in main panel but have noticed that sometimes the sub panel has both LED's lit and sometimes only one LED is lit. Question: Is the surge protector in the sub panel wired differently with White to the ground bar because it is a sub panel and NOT bonded (neutral and ground are separated)? Or is it wired incorrectly?

[@noelpichay9229]

I 've been a long time electrician and this is the one I got more informed about bonding and its nature to equipments etc. that what might happen, thanks!

[@joe72205]

Other than the fault concern, the bond at the subpanel will mean any load downstream will return half its current over the EGC to the main panel even during non-fault situations (IOW, all the time). And since conductors carrying current develop a voltage drop, all the EGCs from that subpanel will be a few volts above earth potential - or fully energized if the main GES bonding is damaged.

[@zm6301]

If the bonding is damaged then current on the ground should be very low as the only path back to the source is between grounding rods at the panel(s) and the utility pole. The only way the ground would be energized is if the neutral is cut somewhere between the panels and you disconnect the ground while power is still on, anything upstream would get energized, anything downstream would not be. Bad news if you happen to be holding the ground wire on the now "hot" side and/or if you're standing in a puddle near a grounding rod. I'm sure people have gotten injured or killed this way and thus it gets written into the code, usually how it works.

[@pontspontbriand7723]

Wow. Hvac tech here. I went down the rabbit hole on this channel from a completely different project I’m doing, and I’m amazed at how quickly I verified some of my questions about electricity and bonding. Super great video. And free ta boot. Wish I had access to you tube when I was early in trade. Great, great, videos. Liked and subscribed.

[@ScrewThisGlueThat]

Dustin... keeping with the sub-panel subject, can you please answer this question... "Can you add an additional ground rod at the sub-panel?" I ask because in a previous build I had a detached garage about 150 feet away from the main panel and the inspector had me add an additional ground rod to the sub-panel in the detached garage. Thanks and I hope you can answer and explain.

[@electricalsociety5593]

Yes it is required. its better to install a ufer ground but if the garage foundation is already poured then you need to install a ground rod. 250.32 (a)

[@rcmrcm3370]

Assume you only bonded the case, and not the neutral to that sub-panel, it's protection so grounding would still cause ground fault trip on GCI, but you don't bond neutral on sub-panel. Bonding neutral in two points creates circulating current, not good.

[@taylorlightfoot]

Separate ground rods are required for separate structures. Since your garage was detached, it's sub panel (fed from the house) needs it's own ground rod too. This is because ground rods have nothing to do with providing a place for fault energy to flow to; fault energy wants to return to the source, which is the transformer, not to the ground. Ground rods exist solely for lightning strike protection and if your garage was struck by lightning and didn't have it's own ground rod, the energy from the lightning would travel down the ground wire that goes back to the main house and you'd melt every other wire in the conduit between the house and garage.

[@motorheadplatt8748]

@@taylorlightfoot Electrical service grounding has nothing to do with lightning protection, it's for personal safety. Lightning rods and wiring are intended to keep lightning out of your building by providing a path to earth.

[@sparkytas]

​@@taylorlightfootIn Australia, which is similar but different, the sub-mains to any physically separate outbuilding only contains phase and neutral conductors, no earth conductor. The subs panel is required to have its own earth stake, which helps ground fault currents in any of the sub-circuits, not just lightning. If a sub-mains are to a conjoined outbuilding like a garage physically in contact with the house, then the sub-mains also have a ground wire and no separate earth stake is required. From my indirect knowledge of the US system, it's basically the same. The US split phase system has advantages in slightly lower risk of death by electrocution because of the lower voltage (before anyone says it's current that kills, voltage has an effect too) in hot to neutral circuits, but a higher incidence of death by fires because lower voltage in 120v circuits needs more current which tends to burn out bad terminations....

[@Just_An_Idea_For_Consideration]

QUESTIONS: If instead of the pole transformer from the electric company grid as the source, we had a completely OFF GRID solar outbuilding as the originating source of power (say 500 feet from the main panel). 1) Do we treat the outbuilding as if it were the grid? 2) Do we create a neutral ground bond in the outbuilding - as the source of power is generated there? 3) Do we create a neutral ground bond at the Main Service Panel? 4) if there is a NG bond at the power producing outbuilding - and a NG bond at the Main Service Panel - if a short circuit occurs - a) WILL IT TRIP THE BREAKER in the Main Service Panel? b) will it trip the breaker in the outbuilding that feeds the main service panel? c) should each building have their own ground rods? Please advise. Your channel is invaluable, and provides great knowledge. Thank you

[@ClericChris]

I'm interested in the theory when a generator is used. Has there been a video on that. I've found your videos most helpful.

[@paaao]

You bond the ground and nuetral at the source, and anywhere power is transformed. So in the case of a generator, it is the source of the power. You want any equipment fed from it, to have a path back to it, not back to the house service ground, aka the utility's ground. Ideally, a generator used to feed a house in the event of say, a power outage, should have a means of disconnecting and isolating from the utility. ATS switch, or manual means to avoid backfeeding the utility in the event of a fault, or open. The utility grounds out all the lines prior to working on them, and sometimes in certain blackout situations. Homes running generators that are hooked up improperly, back feeding, or even sharing/referencing the utility neutral/ground, usually burn up pretty fast in these situations. The utility feeds your meter with 240V hot/hot, and brings a ground/neutral wire by center tapping the transformer. This center tap is their bonded neutral/ground. It is directly in the center of the 240V windings, which is why each leg to neutral/ground provides 120V.

[@vtgoldprospector]

@@paaao Typically in whole home generators there will be a transfer switch that takes the place of the main panel. This transfer switch should be rated as "service rated" meaning that it has a main breaker (not an ordinary breaker). The main bonding jumper that connects the neutral and ground is located here which was previously located in the main panel. Since there can be only one bonding jumper, the existing main panel should be updated as a sub-panel so that all grounds and neutrals are separated, the main bonding jumper removed and the neutrals landed onto an isolated bus bar. The wire that was between the meter and the main panel should be replaced to now connect the transfer switch to the panel and will have an extra conductor for the ground, which it previously did not have coming from the meter. This is the difference between an SEC (service entry cable L1-L2-N) and an SER (service entry riser L1-L2-N-G).

[@kinterest1562]

​@@paaao watch Mike Holt videos. Grounding and Bonding at the generator is dangerous!

[@Gary-ts6dh]

1:57 - Good save! I had a "discussion" with the instructor in apprenticeship class back in the day over this very topic. The grounded conductor carries juice all the time; the grounding conductor only carries juice in the event of a fault.

[@jesusm8081]

Nice explanation. Also to add even if there is no fault. Bonding at a subpanel creates a path for your neutral to travel back to the main pane / transformer through ground. Keep up the good work.

[@notreallyme7465]

I had a panel that the power would go way high then low whenever it wanted to. What I found was a loose neutral buss bar. Everything was loose. So, it would find different routes to neutral. The lights would get really bright and the picture on the TV would get bigger and smaller. Proves why you don't want things going through wrong places. Very well explained as always. Thanks

[@LTVoyager]

Maybe I missed it as I had a couple of interruptions while viewing, but I didn’t hear probably the most significant issue and that is the return current path during normal operation. I heard you mention a short to ground fault and a short to neutral fault, but not normal operation. If the dryer is operating normally with no internal faults, but you have the neutral and grounding conductors bonded at the sub panel farthest from the service entrance, the return current on the neutral will divide at the sub panel and now the “normal” return current will travel the rest of the way on both the neutral AND the grounding conductor all the way back to the service entrance. The current proportion will be based on the resistance of the neutral and the grounding paths, but likely will place substantial current on the grounding conductor. That is probably the biggest reason not to bond subpanels. Yes, the two fault conditions matter, but having current on the equipment grounding conductor during normal operation is the most insidious issue of all.

[@bryanduchane2371]

Absolutely correct and not many licenced electrician know that. What I've never got a good answer from anyone is why they require oversized neutral conductors??

[@LTVoyager]

@@bryanduchane2371 I thought this had been changed some time ago. This reference says in 2008. Since I’m retired, I no longer have access to current NEC documents. “This is fully recognized in the latest (2008) edition of National Electrical Code. Specifically, Article 310.15(B)(4) addresses the question "Should Neutral Conductors Be Oversized?". Noted is that "for NEC editions up to and including the 2005 Code, the neutral conductor ampacity was usually 125% of the maximum continuous current allowed by the overcurrent device." This is immediately followed by: "Revised for the 2008 Code, both 210.19(A)(1) and 215.2(A)(1) include a new exception that permits a branch circuit or a feeder neutral conductor to be sized differently. The sizing is now permitted to be 100% of the non-continuous load plus the continuous load, thus permitting a reduction in a neutral conductor size (calculated from previous editions) by as much as 25%."

[@bryanduchane2371]

@@LTVoyager From what I remember from my 25yrs in the Electrical Distribution business, I think an oversized neutral had something to do with harmonics and the use of digital equipment in a facility. This popped into my head as I was reading your reply. Only been out of the business since 2015 and the old saying if you don't use it you lose it couldn't be more true. I could easily get back in the industry, but would have a steep learning curve to learn all the new technology that has been released since 2016..... Loved the industry. Met some of my best friends through it.... It's a very rewarding career.

[@LTVoyager]

@@bryanduchane2371 I’m a retired EE and I don’t remember any discussion of the need for a larger neutral or related harmonics issues and I was going to school in the last 70s and early 80s. I always figured it was just an error carried forward from people who didn’t understand the phase relationships in AC and thought you had to add the currents from the two hot conductors as though it was DC. I never knew the history there.

[@motorheadplatt8748]

@@LTVoyager The harmonics are caused by many PC's in the same building and on the same transformer using high frequency switching DC power supplies. This problem didn't occur until around 1990.

[@waynepowell567]

Excellent. My Dad was an Electrician back in the day and he would approve, Thanks for sharing. Be safe, Man.

[@MyClutteredGarage]

This is still confusing to me, but the example with multiple panels really helped a lot! I'd probably have to do or see an actual exercise/install from start to finish. Maybe you can do a benchtop demo?

[@vivesanta3026]

Love how you read that comment with out making comments on his spelling. Love the cut to the business attitude!

[@winstonwright3613]

WHOA!!! When Dustin's Beard be GROWING AN INCH IN HALF A SECOND .... I know some serious s***is about to go down!!

[@motorheadplatt8748]

It's like Pinochio's nose.

[@dwmcever]

So, my question is does the Sub-Panel Metal enclosure need to be grounded to a ground-rod. If the Ground bar is electrically attached to the Sub-Panel Box and is grounded by wire to the Main Box does that count as ground? In same bldg or in remote bldg? Think your readers might be interested in this.

[@yandr4life1]

Full disclosure: I'm not an electrician, but what he has explained is you always want to go back to the source of the power, your service panel, where it is grounded with a rod. Any feeds off that panel, regardless of location, always goes back to the original source. But I could be wrong..

[@dwmcever]

@@yandr4life1 I was looking to an Electrician for the answer. One current on the Code. My code books are out of date. As am I. ;-)

[@0pinion0lympics]

10-210 Grounding connections for solidly grounded ac systems supplied by the supply authority (see Appendix B) The grounded conductor of a solidly grounded ac system supplied by the supply authority shall a) be connected to a grounding conductor at one point only at the consumer’s service; b) have a minimum size as specified i) for a bonding conductor; and ii) for a neutral conductor when the grounded conductor also serves as a neutral; c) be connected to the equipment bonding terminal by a system bonding jumper; and d) have no other connection to the non-current-carrying conductive parts of electrical equipment on the supply side or the load side of the grounding connection.

[@KevinCoop1]

@@dwmcever Would a retired electrical design engineer 35 years on the job work for you? If so, if the sub panel is within the same building, then wired exactly as Dustin showed on objectionable current diagram. If a feeder is run from one building to another building, still separated, but a Grounding Electrode Conductor (GEC) and Electrode(could be ground rod) is required. Please be aware that the “To Earth” connections (ground rod) has absolutely nothing to do with this video. Electrodes(ground rods, metal pipes in grade, re-bar in concrete, etc) are connected to electrical systems to dissipate surges and lightning strikes. Nothing to do with ground faults. BTW, feeding other buildings from one building grounding, flip flopped back and forth several times in the 70’s thru 80’s. Hope this helps.

[@BillC-64]

The ground for a sub panel is equipment ground. The ground rod is for the earth grounding system - for a path for lighting or static electricty. They are two different things.

[@tray8411]

Heres a Q for all the electricians on here.. When wiring a cabin and its fed by a generator, Do I bond the panel? Great stuff sir

[@frankcarone3657]

If you bond the grounding conductor at multiple points, you also create a current differential across those points, so your grounding is no longer at one potential and there is current flow across the bonded (grounded) metal parts. This mean you could get a shock by, let's say, touching the metal on your laundry machine even though everything is working fine and there is no short.

[@sliceronsteam]

Yep, there are so many bad videos telling people the wrong info on connecting a hot tub. Hot tubs are required by code to have a GFCI shutoff near the tub itself so are a small subpanel in every case. If you bond neutral and ground on that hot tub panel then you have a parallel loop back to the main panel and electricity is a self-leveling force of nature. If your hot tub is drawing 120v and 2 amps, then you absolutely have roughly 1 amp on the ground leg and 1 amp on the neutral leg of that parallel loop at all times. The hot tub can draw 240v 10+ amps for its largest pumps and heaters and you are safe from that because it bypasses neutral, but all of the control boards, lights, speakers, and smaller pumps might run on the 120v. The GFCI won't trip because it can only protect downstream and the parallel loop is upstream from it. Everyone using the hot tub is relatively safe, but the house is now a danger for any other electrical work.

[@okaro6595]

No, you would not get a shock unless the wires broke but it could cause stray currents that cause problems with AV and IT equipment. For you to get shocked there would have to be loss of tens of volts in the wires. Such a system would just not work. For some reason people need to make things too dramatic, as if you die if some rule is broken.

[@johnlieber4687]

In your example you have multiple subpanels all flowing through each other. In the case of a single subpanel, say in a garage, in my mind it seems like having the neutral and ground bonded in the subpanel means that during everyday operation, neutral current can flow back on either the neutral or ground wire or both! This does not seem like a good idea, and I would be very curious to know why anyone EVER thought bonding these in a subpanel was a good idea. Maybe I am misunderstanding something. Thank you and love your channel, very clear and to the point!

[@user-rtjkibvwa]

I think this is a true reason for not bonding in sub panels and not how the author of the video explained (he didn't)

[@ChadCourtneyTAZ427]

In short all sub-panels have their neutral bonded to ground via the main panel. But adding extra bondings at the sub-panels creates dual pathing between main and subpanels for a return path which will result in current on the ground, which is bad.

[@CybekCusal]

No. Bonding occurs at the service termination not the main panel. Don't give advice if you don't know what you are talking about.

[@wim0104]

in recent years, we now see more panels/pans that combine the meter and the service termination in one box, the first panel(s) fed from that would be the main panel(s). the neutral+grounding bond has to be where the service is being terminated/landed. So that might NOT be in the panel you're thinking of. Just remember to never turn a grounding conductor into a neutral with a rogue bond: an energized grounding system is extremely likely to shock people, because the grounding system is bonded to everything: plumbing, metal enclosures (washer, drier, heating,...), metal cages of fixtures, chandeliers etc... ppl will be touching it.

[@rthinds]

@@CybekCusal He knew what he was talking about. Bonding occurs at literally every main panel, which is "service termination". Duh. You said exactly what he said. Please re-read it again before commenting again. Mmmkay?

[@plaintiveplainvanilla9729]

Even just as a layman with a very basic understanding of home wiring, this explanation really laid it out for me. Thank you for the clarity.

[@RusredGuTH]

You and other electricians that do vids like this are blessed with wisdom and the love for others is appreciated. Thanks for being awesome 😎. I’m well on my way to being an apprentice that knows his sh** before I even get an interview

[@garynumen13]

Can't tell you how many times people have told me they were electrocuted!! I try to explain, but... well. Thank you for making the distinction.

[@michael.a.covington]

16:04 That is the key point: If the bond occurred downstream of the service entrance, a ground fault would elevate the neutral (raise it above ground voltage) from the bond all the way back the service entrance, causing incorrect and possibly damaging voltages all along the way.

[@d46512]

That would be bad. Meanwhile, if a neutral wire becomes loose on any circuit, the ground potential throughout the house would be raised. A very dangerous type of fault.

[@mikeburke1993]

Dude, your videos are good. Please keep making content. Very simple to understand. Lots of folks don't explain well. Hence, why there are instructors, not lay people explaining.

[@jimmckinley8110]

If a neutral is bonded to ground anywhere in the house, current could travel on the green bond wire or any metal bonded to ground in the house, back to the neutral in the service panel during normal operation. This can cause shocks when 2 metal parts are touched.

[@jasongayman3994]

Exactly! We want our metal panels and equipment chassis to be at earth ground (0V). Wiring has resistance just like the loads they drive. And while we would like for there to be zero voltage loss, some has to be tolerated until we can find an affordable way to wire buildings with superconductors. In a 120V world, the neutral can develop a slight potential difference from earth ground the further it is away from the main panel. That's fine and acceptable. However, if a sub located on the other side of the building bonds the ground and neutral, now the neutral will also be at a non-earth potential. And while the voltage may not be that much above/below earth ground, depending on the situation it could be enough to introduce hydrolysis (accelerated corrosion essentially of all exposed metal parts that may find a slight path to ground) and other undesirables.

[@mechantics]

This is great information. In preparation for my NACHI (home inspector) exam, I had to know that this is the rule, but I wasn't completely understanding WHY. Electrical is so often misunderstood, and while an uninformed explanation might be able to satisfy a specific scenario, the risk of that improper logic being detrimental in another application is great. Thank you

[@yren3386]

Pointing out one thing: In most SFH, there's no ground conductor coming from the service. Ground is provided on premise by the ground rod. And that's why you need bonding: because ground bar alone doesn't provide enough fault current. If there was a ground conductor provided by the service (for example many commercial buildings have a shared ground across the building) bonding is not needed, because that ground conductor provided by the service provider is a good enough low impedance path back to source. You can still ground the service-provided ground again on-premise, there's never too many grounds on ground wire. BUT don't bond it with neutral again, there can be only one bond.

[@Wheel_Horse]

I noticed that also. In the first graphic he's showing FOUR wires from the pole... typically there are only THREE. The two HOTS and the NEUTRAL. As you say, the GROUND ROD is at the service entrance.

[@Sphinxone]

Thank you for the content. After watching this video, I confirmed that I was correct and the electrician did it incorrectly when installing my new breaker panels. He didn't ground them back to the service panel and he wired up my CAFI breaker's wrong too. He had one neutral from one circuit going to breaker "A" and breaker "B" circuit neutral was going to breaker "A" and kept causing the breaker to trip. It took me a few minutes to figure out what he did wrong, but now that I know, it is a easy fix.

[@taylorlightfoot]

Good info, not the clearest for people just learning though. Your first diagram showed a ground going up with the service wires, we don't get a ground wire from service. ground rod is only there for lightning, you can just say that, showing the neutral midpoint of the washing machine motor is confusing, makes sense for service transformer. You could touch on the fact that ground wires are sized smaller than neutrals and if we have a parallel path, we could overload the ground wire with current meant for the neutral wire, etc.

[@spruce_goose5169]

The first diagram is showing the Grounding Electrode Conductor (GEC) - the wire to the ground rod - not a ground feed from service.

[@spruce_goose5169]

@tim g "the Earth (Ground) rod makes sure the Neutral wire is at Earth potential (0 Volts). If the Neutral wire is not at Earth potential it is possible, likely even, for it to rise to Mains potential. " This statement doesn't make total sense. Mains potential referenced how? If ungrounded, a system would have indeterminate potential (voltage) to ground. There would be no path for mains current to flow through someone or something to ground, thus 'mains potential' would not really exist. Taylor is correct that the earthing helps to dissipate static charge, though all the reasons to earth a system (or not) is certainly complicated.

[@spruce_goose5169]

@tim g "By connecting the Earth rod to the Neutral wire you ensure that ithe Neutral is at Earth Potential (0 Volts)" Yes I agree with that, but you still are talking about 'mains potential' without discussing any reference. As you say, if you unground the system from earth, there is no ground reference any longer, thus what is the 'mains potential' that you reference a potential between? As I'm sure you understand, voltage is a measure of potential between 2 defined points. If the earth is not part of the circuit in any way, then there is no 'Mains potential' to discuss in terms of reference to earth. It is, as stated earlier, indeterminate. Am I just misunderstanding your point? Where would you propose placing multimeter leads to measure this 'mains potential' of a floating system (what 2 points in the system) and what would you expect to read on said meter?

[@spruce_goose5169]

@tim g re your second response... I was responding to the OP (Taylor) pointing out that the green line he saw was likely the GEC. (you know, the copper line that bonds the main panel to the grounding rod outside.) I don't know what you are going on about with this 'the neutral is both ground and neutral until separated' business. Sure, that is sort of conceptually true, but no-one should ever draw those as separate lines with different colors for educational purposes. But I don't think he did, as I think it's the GEC he was drawing. Not that complicated, don't make it so.

[@spruce_goose5169]

@tim g You can call it whatever you want (yes TN-C-S is correct terminology, though here in the U.S. that terminology is not commonly used in residential) but you're missing my point. My point is that he almost certainly did not draw a separate green line to depict a TN-C-S system. Far more likely IMO that he drew the GEC. No where can I find a diagram of TN-C-S drawn that way. It would be confusing as all heck since drawing separate lines is indicative of separate wires. It is clear that ground fault current uses the ground/neutral bond to travel to the transformer via the neutral (low impedance path) to clear a fault.

[@Bill98533]

That was explained so well.; Thank you! Our office had an electrician wire in a sub panel and he bonded the sub. Thankfully we had only a power bar plugged in on the sub and burned it up with 240 volts. He knew exactly what he did when that happened. I've been looking for the explanation ever since.

[@okaro6595]

Bonding the neutral and ground does not cause 240 V on normal sockets.

[@phillipsusi1791]

@@okaro6595 Yea, that's more like getting the neutral swapped with the other leg instead.

[@Wrenchen-with-Darren]

Great video... now, PLEASE, PLEASE, PLEASE, do a vid on grounding rods. I've been told more than a 1000 times, to put grounding rods at every building. Here on the farm we would NEVER do that ( I know, farms are different ) because of potential "stray voltage". And, what does NEC say about multiple grounding rods? Thanks SO much.

[@jim_locks]

Same. I've read that you should have a grounding rod at a sub panel. I'd love a video explaining that.

[@Wrenchen-with-Darren]

@@jim_locks read? Last I knew. N.E.C. 250.52 (A) (5) talks about grounding electrodes. I believe, there can only be one per service.... per N.E.C. but, I've had inspectors require more????

[@Blahblahblah8016]

Yea , are grounding rods primarily for lightning? Or what else are they for? How many do you need, where and why? I think a video focusing on grounding rods would be nice!

[@45-308]

Most electrical systems require a grounding electrod. The NEC generally requires all grounding electrodes be connected together, "bonded". A building may have more than one grounding electrode available, the water main and the rebar in the footing. If you may need to add a grounding electrode if there is not one available such as in a pole barn. The most common way to do this is with a driven rod. "Ground rod" The NEC says if you have 25 omhs or less resistance on this connection to the earth one electrode is sufficient. If you have more than 25 ohms resistance a second electrode is required. So the common practice is to add a second rod instead of trying to prove you have less than 25 ohms of resistance. The connection to the earth gives you electrical systems a reference to earth and helps stabilize the difference in potential between your electrical system and earth. It also creates a path to earth for any electricity the was induced on to your system that doesn't belong there.

[@Wrenchen-with-Darren]

@@45-308 that helps, thanks. It gives the electricity multiple paths back to the main panel, if there is a ground fault... wait, we don't want that???? I give up.

[@shemicdee780]

Yes I'm reading some of the comments. You are an excellent teacher. Ty

[@electricianron_New_Jersey]

A: Because we don't want a parallel path specifically for fault current (to clear a fault, faster, much faster).

[@psywiped]

Because you don't want to create a ground loop that can have current induced by a magnetic field.

[@electricianron_New_Jersey]

@@psywiped A ground loop?

[@graciemiller9596]

Thank you very much Dustin for explaining that subject so clearly. It was such a simple explanation for me to understand. Thank you.

[@SSHAKEandBAKE]

Why does your illustration show a separate ground coming from the transformer and feeding the Main service panel? You should have only your 2 phases and your grounded conductor.

[@jamescameron2969]

There is a ground coming from the transformer as well. It’s the bare wire.

[@ricardofonseca1537]

Could be a cold water and ground rods wire

[@bryannorris]

Truth!!

[@SparkingRelativity]

Could be a flying saucer

[@joealexander868]

Look again at the illustration. He is drawing over his lines to show the path, not adding a ground.

[@lloydrmc]

Dustin, You are a gifted teacher. I understand this now.

[@SK-yw5ih]

The reason you dont want bonding in the sub panels is that you dont want REGULAR current from the white wires travelling on the grounding (green) conductors, because those are supposed to be at zero volts except they are to carry current under fault conditions, as that is what keeps you safe in the event of a fault. THAT is what they mean by objectionable current. If the green or bare bonding (grounding) wires are carrying current under normal conditions because they are bonded to the white bus in the subpanels, it could lead to someone getting a shock. I don't think you explained it very well. Also, the white (neutral) going back to the transformer is grounded at the pole transformer. Also, the ground rod should take most of the fault current, if it was done right, it does't have to go all the way back to the pole transformer. Bottom line is don't take electrical advice from youtube videos or comments, hire a licensed electrician.

[@djaztec97]

Your drawings help me visualize what's really happening in the circuit. Better than someone trying to talk without drawings, and I have to picture what's going on to understand.

[@hvfd5956]

11/2023 - FYI there are two new Oncor substations being built right now in Hutto. I was amazed at how big the foundation had to be for the tall poles entering and leaving a drop station like these. One I saw must have been 18-wheeler truck sized. They built the frame one day, the next day it was dropped into the hole, and the day after that they must have bought out all the concrete in central Texas. The foundation now sites waiting on the pole to be put together. A friend of mine used to live in a long ranch style house in Bee Cave. I seem to remember he had a 700 AMP service off of his own transformer. That house had at least 4 sub-panels. It was a massive house. We were trying to work on a radio building down by the barn and the closest plug was up by the swimming pool. We quickly found out that whoever had installed the pool did not do the grounds right as we got a bit of a tingle when we hooked up this building. Fortunately, we figured it out and 20 years later, that building is still in use. Thank You for what you do. I always enjoy watching your videos.

[@optimisticallycynical.814]

Been doing electrical for years , Best explanation I have ever seen

[@michaelbourassa2379]

Thank you it's really unbelievable to me that you have to explain that. Even though you made it so simple to understand people are still having a problem with it. That's what I don't understand. But I see so many messed up panels that aren't done right.

[@chrisbramatali5878]

As a Control and Electrical Engineering Finalist Student, i am working on my final year project based on your two videos (Why Neutrals and Grounds are Separated in a Sub Panel and Why Neutrals and Grounds are Connected in a Main Panel. Design, Simulation and Prototype of a GFM, a meter to interrupt flow of power to a delicate house/industrial system on condition that it has met/satisfied the Effective Ground Fault Current Path). So as to eliminate the negative consequences of poor installations and only qualified electricians doing the clean job. Hopefully, i can be able to make more inquiries/questions and guidance from you! Looking forward to your reply. Thank You!

[@cetyl2626]

I've had a great many fond memories with my son helping me with electrical work. He helped me with the wiring in the shop (a separate building), but we've really only bonded at the main panel.

[@HollandIdeas]

Thank you! great explanation for someone like me who wants to do some work on my home but didn't really understand the bonding at the service but not on the sub-pannel. I have a mobile home that has a sub-pannel in the house that was built in by the manufacturer and a service panel outside the house on a pole. I plan to move the service to the other side of the house and take the service underground to the house. I plan to do the work myself and this was very helpful.

[@benhasler6056]

I'm glad I watched this video, I never understood when my boss told me to bond or not to bond a panel. I just went with it.

[@postiemania]

Electrician from Australia here, objectionable current love the terminology.

[@whitleyca]

Really helpful as a layman with a very basic understanding of circuits. Thanks for taking the time! I am curious if anyone out here on YT may have some insight? I have a rural piece of property w/ a small cabin connected to the grid. There is a service panel on the pole (coming off the transformer) and a subpanel on the cabin. The subpanel has a separate ground bar where everything from the cabin is grounded: outlets, lights, refrigerator, etc. From this video, it all makes sense that grounds at this subpanel are NOT bonded. BUT... there is also a single pole, 30amp RV outlet hanging off the subpanel. For that outlet, both the ground and neutral are connected to the neutral same bar. Again from the video, I would have expected the RV ground to connect to the ground bar. Was the RV done incorrectly?

[@hectorarias5034]

Best explanation thanks a lot. My pool guy did not bond all my pool equipment to my sub panel I will have to do it. This is great video.

[@MrGsxr10001]

Thank you so much for making this video. I have complete confidence to wire the sub panel out to my man cave now. I was stuck on the bonding screw. I'm good to go now.

[@michaelmakowski8223]

That was the best explanation of objectionable current I've come across. Thank you.

[@TCAPChrisHandsome]

This explanation was perfect. I wasn't sure why the main could have neutrals and grounds connected, but any panel after had to be separated

[@enriquerodriguez2451]

Thanks it’s perfectly clear I needed that wisdom to keep safe

[@chasmontecarlo7271]

Great explanation , I’am in the process of putting a outlet in my garage and was concerned about the ground and neutrals it’s the first point of disconnect is my panel.Thank you for knowledge I know I can do it.👍

[@eboneezeradams1821]

Glad I saw this video. I do have a scenario where there will be multiple panels. Each will hop full 200 amp service. I have a main pole with meter and from that box I have an RV hookup 60 feet away with a 100 amp panel. 70 feet In the opposite direction, I have a 200 amp exterior panel, and 120 feet from there is a conex container that will have a 200 amp interior panel and another container 100 feet from the last with a 200 amp interior panel in it.

[@PhillyFixed]

Great explanation! When I was trying to wrap my head around this a few years ago, I came to the conclusion that the easiest way to conceptualize it is by equating it to tying the ground and neutral together at a receptacle. Would totally defeat the purpose of the ground conductor. (Of course you're not dealing with a breaker at a receptacle, but... You know)

[@Thrunabulax10]

good explanation. i never thought of it before, but to insure the circuit breaker can trip when something goes wrong, you do not want additional "ground paths" out at the sub panel

[@nguyenvinhtuyen0103]

Your teaching style is wonderful. I am myself an electrical engineer but still learn a lot because they never taught me in school about this.

[@ElectricianU]

thank you my friend!

[@upsjohn1960]

Wow! Electrician University- Your a Great Instructor 👍

[@parlenkow]

This Chanel is Gold in value!!!!best info in KZbin thanks

[@Ibuildit2817]

Just came across this while checking out videos and this is by far one of the best videos I've ever seen! Excellent work.