The best channel RU-vid channel for Electricians. Keep up the amazing work Dustin. I always look forward to your videos even if I already understand the topic you're discussing.
@@rickyperkins232 Not an electrician but I believe its due to metal stud construction with metal conduit running the wires. In residential environments its wooden studs.
Nice job using the smart board. I like how it has a slight gray background allowing you to display the white conductors. This was an issue on the white boards in earlier videos. Great way to solve it. Keep up the good work!!!
Thank you for all the great videos. I think I have a good example for you. I bought a 1940's drill press that did not have a grounded plug. When plugged in, it operated with no issue. I got it home and plugged it into a grounded metal outlet and again it worked with no issue. The problem came when I went to unplug it and touched the grounded outlet box and the metal housing of the press at the same time. Thats when I got zapped. Upon inspection, the insulation on the hot inside the motor was worn making contact with the motor case. This energized the whole press. I replaced the motor and grouded the case so everything is fine now. Thanks again for all your educational videos. I am not an electrician but I appreciate the way you explain your craft in an informative and entertaining way.
Guys remember here in the USA, there are multiple utilities that have corner grounding that will LIGHT YOU UP!!! Always check voltage to anything metal!! Oil field is the most common! Be safe guys!
Rob a very good point in my area we have a lot of comer ground systems. In the Irrigation and farming end of the industry. It is usually on older power systems for us because power companies don’t install corner ground systems because of safety reasons.
I really appreciate your way of explaining things simply in a way that someone not in the industry can understand. I'm a manager at a warehouse and small production facility. The guy that we had who took care of the maintenance stuff and had dealt with electricians and getting equipment hooked up moved, so these videos have been really helpful in helping me understand the basics of how things work. Knowing what the different plugs are for, how the system works, and what to keep in mind will be very helpful when I have to deal with stuff and hire an electrician to do work.
When I was a kid back in the 80s, we lived in a house that had been wired in the 1920s, and there was a problem where if you touched the refrigerator and the freezer at the same time you'd get shocked. The whole house got rewired in the late 90s so that's not a problem now, but it was a problem then.
chances are very likely, the house was wired with knob n' tube and no grounds were used, just a hot and neutral. So the fridge or freezer had a fault and the other was grounded somehow., so not a good situation.
I had a friend that their fridge and stove were that way. If you flipped the fridge plug it went away. They would flip it back on purpose sometimes to mess with their sister. She'd open the fridge and bump her rear into the oven then jump.
No ground or ground was used for hot. Seen plenty of ovens ran with 10/2 with the ground acting as a neutral. So basically what happens is "no ground" you touching it creates a short which makes it want to take a ground, but since is none, you're it. What would worry me if that never traveled back to the breaker, then it'd never break.
The “strap” as you called it that’s on the plug receptacle is metal and connects to the green ground screw on the bottom side so when that strap has 2 screws through it holding it to the metal box there are 2 screws and the strap touching the metal of the box which already ground the metal box via the green screw that’s connected to the bare ground wire. Why should you have to also add a grounding wire to the metal box if it’s already grounded that way? I’ve tested with a meter to confirm the plug receptacle “strap” is conductive through the metal box enclosure and to the bare ground wire to see for sure. I understand why it’s done but I also see the “strap” fastened to the metal box thus creating a grounded connection without an additional connection to the box.
I used to think the same thing, but experience has improved my understanding. There is a very small chance that paint, dirt, or just loose screws could prevent the strap from contacting the box.
This was a very informative video. I am a IBEW electrician for 47 years, I hope the young electrician’s watch this and understand the purpose and most important thing the safety aspect of a equipment grounding conductor. You explained this very good. Keep up the good work.
As a young electrician, we definitely love Dustin's videos. I'm still an apprentice and many times I'll see something in the field and reference his videos to learn more about it in depth. A lot of us young guys don't want to only know how to do the work but why as well.
@@esl4058 ….thats great that you want to know why……. Keep up the positive attitude brother! Study, study, study…..keep learning, look up mike holt……he has so much info…
I usually tell the difference between Tip to remember difference from GROUNDED AND GROUNDING CONDUCTORS as the G in the GroundinG as the G for Green for a green ground-screw. And GROUNDED as the Neutral.
Appreciate you sharing this basic info. As a homeowner with some facilities maintenance experience, you provide great insight into the basics of electrical work. I greatly appreciate your work on these videos as they are helping me to become more confident in working with electrical components.
Thank for sharing. We have found within our 40 year plant the metal tanks and pumps were not grounded properly. So we are now running miles and miles of ground cables and rods
Dude. You kept a straight face during that intro. Your abilities and impulse control skills are top notch. Ground, grounded, grounding, bond, bonded, bonding. They are things. NEMA 4X we always install a ground bar and no we don't mount that bar with 10/32 screws, and we're not supposed to drive screws through the wall of the box, since the box has to maintain it's integrity, so what do you do in that situation? Anyone?
I'm not a professional, but this question and the great explanation given cleared up a lot of ideas in my head that were a bit fuzzy. It now makes complete sense to me. Thanks!
My first question when I saw the title was "how would you bond a plastic box since it's non conductive?" I haven't watched the video yet, but I'm predicting that that's pretty much going to be the gist of it.
Great job on the channel. Been here from the start. My go to source for real world info on the subject. Great teacher for the new generations (well everyone) especially. Def makes learning the principals fun.
A few weeks ago one of my receptacles had the hot contact the ground, but there was no grounding wire going back to the main panel. I found out when I touched the back of my pc. It wasn't a strong shock luckily. It's fixed thanks to your videos.
Install some GFCI receptacles. No reason for not doing this. They will save your life. But think carefully about where you place them in the circuit as one GFCI receptacle will provide protection for down stream receptacles.
Good video, as you explained the basic concepts, including the code. Maybe telling your audience, that every part of the code was a result of an injury or death, as in (WRITTEN IN BLOOD), might curtail some of the remarks, from the so called DIY, that seem to have an answer for everything.
Great video! Super informative and the drawings helped with that point too! Also, thanks for the tool that I won from your holiday give away Dustin! Looking forward to seeing what you come out with next
Electrolysis is a good reason to bond metal enclosures to conduits. I have seen wires in front of me burn up the insulation because of this, it was # 12 wire solid. But it was pretty shocking to watch it happen with my own eyes in front of me, after replacing some conductors for a boiler in a apartment building .
Our plastic boxes in Canada have a metal band between recepticals mounting holes around back of the box that we have to bond. Keeps all screws and devices frames bonded, if our switches down press tight against it we have to actually bond them as they usually have metal in the construction.
This was a great, simple explanation. Assuming one is not using armored cable and the box is not exposed interior, Is there anything inherently better about metal boxes over the extra thick plastic boxes? I slightly prefer metal boxes but I don't really know why.
It's not uncommon to run across people in one type of trade or another that are pretty much strictly doing what they've always been told to do and never really understanding a cause-and-effect from point A B to C,D so if they encounter something at Point X or Z to be able to think back and apply it. In other words they're parts Changers more so than mechanics.
Plastic box isn’t an insulator.”, as you mentioned. It’s simply non-conductive. The question goes beyond connecting a ground to a plastic box; the question applies to not connecting a ground to devices like a smoke detector.
And that’s why a double insulated device (e.g., corded electric drill) indicated by a square box within a square box on the device’s nameplate does not have a grounding conductor (i.e., two conductor cord and plug).
Also- the NM cable that supplied our water heater went under a NM cable staple and turned 90+ degrees (along the flat side of the cable) and eventually it shaved through the insulation. Fortunately, it was exposed where the water heater was located and we could see it, but it really was a fault in the middle of the NM cable- and it was stapled to a stud. It CAN happen, unfortunately. We were VERY lucky to discover this before the house burnt down. We only knew about this because the water heater stopped working. No CB trip. But the wood stud was darkened. In this house, later I also found other NM cables that were seriously stretched between the staples and had rubbed through the first layer of insulation- this we found when we renovated and removed the ceiling.... FML!
Yours is one of my go-to channels for Electrical-related topics .. You do a FANTASTIC job explaining theory and then illustrating in a practical manner. That being, and for example: The board you used .. Wow. WHAT exactly is that and how would I get one? Thanks in advance & be safe.
The receptacle provides a bond through the tab under the mounting screw. The electrical code is a compilation of margin on top of margin, and it’s getting worse with all of the required dedicated circuits.
Seeing you are very competent and knowledgable do you ever talk to the people who write the manuals and ask why they do not do a better job with 'this grounding' subject and make it clearer and easier to understand?
I always say that I’m paid to melt metal with electricity,so you don’t want me messing around with any electrical wiring. In the rare case that I have to though vids like this help increase my chances of success without any of those pesky things like fire or death. Thanks for this one. Very clear and easy to understand.
Great video and use of smart board 👌 I would love to see a video on AC frequency and learn more about what that is, is it standardized, how is it measured, do different appliances convert to different frequencies, can you convert to different frequencies, is the frequency set by the power plant or does it change at different steps like in high voltage wires, etc? Keep up the good work 👍
If you use a hydroelectric plant as an example, in the US the turbine is spinning at 60hz which is what creates the 60hz on the power lines to your house. If that turbine is designed to supply up to 1000amps of current then they need to stay below that. But if another turbine that is suppling that grid fails then more load is applied to the 1000 amp capable turbine. If we end up with a load of 1050 amps the turbine actually starts to slow down which is really bad because it starts producing 59 hz electrical frequency. At this point they will turn of the power to a couple thousand homes to reduce the load on the working turbines so they can maintain the 60 hz. There is actually automatic disconnects in some power grids that get triggered by a low frequency on the grid, like 58hz, and it will just disconnect power from those homes to save the rest of the grid.
@@ecospider5 Great explanation. The opposite also happens every day just before lunchtime when all these new solar plants start injecting lots of power into the grid. That makes the frequency go over spec to 61hz and beyond, and the thermal and hydro plants have to try to throttle back really fast. Most of them are not designed to do that. That's why we have been building natural gas peaker plants and need more electrical storage capacity.
Hey, I love your videos. I'm an electrician myself from South Africa. I've noticed that U.S electricians hardly ever use insulation resistance (Meggers). I haven't seen them used when they commission an installation or when doing fault finding. I usually only see you guys use them when testing motors. When there is a potential ground fault on a piece of equipment I notice you only use the continuity function on your multimeters which is fine for a direct short but not really when there's partial insulation breakdown. Could would love a vid on why this is or if it's just not a requirement in the states.
I’m a U.S. electrician and do a lot of new installations in data centers. I use them all of the time. We have to meg all of our feeder circuits and document the results on paper. Where do you get the idea that we don’t use them?
@@RB-xv4si I guess all the videos I saw of U.S electricians I just hardly ever saw them using it. Again, it's not that I never see them using it, but just not in residential fault finding. Like I said, whenever I see them test if a phase is down to earth, they use the bell tester on their multimeters instead of an insulation resistance tester. I was referring mainly to the use of a megger in a residential setting.
@@lechzekjacobs2752 oh ok. Well I can’t confirm or deny that, as far as residential construction. I did residential service for a while and the only time I used a megger was when we were testing underground branch circuits to neighborhood pole lights. The only reason I can come up with is that those direct buried underground circuits are subject to constant degradation from the elements and there is some value to using a more involved megging test that can show gradual degradation of the insulation over time. For your typical indoor residential circuits that aren’t subject to these conditions, a circuit failing is usually the result of a dead short and there isn’t much value in using anything other than a continuity test in these situations.
@@RB-xv4si understandable. Thanx for the insight. In South Africa, to commission an installation (residential, commercial or industrial,) every circuit within that installation requires doing an insulation resistance test (among other tests) which needs to be recorded on the test sheets. Minimum of 1 megaohm is considered a pass. Anyway, I love seeing how different countries do electrical work. Broadens this young electrician's mind. Thanks again.
The washing machine and dryer example you use is sadly is a very apt one. It was one of the reason why in the NEC 2020 GFCIs were required for those circuits because small children have died playing around these types of equipment when there was a ground fault.
Thank you Dustin for your easy way to explain all technical information on your videos. I'm watching you from Argentina. I hope to become an electrician in Canada soon.
Shout out to you from Canada. I have been watching lots of your vidoe. you are an amazing teacher. you have clarified alot of confused terms to us. I find Canadian electric Code mch less the same as USA.
A well grounded tutorial... in electronics for devices its refered to chassis ground. As apposed to earth ground. I understand your explanation. Thank you.
No it is not. The chassis ground is something completely different. Chassis grounds typically form part of the normal operation of an electrical system. It is just a convenient way to connect electrical devices to each other. Current then flows in that chassis ground under normal operation. A classic example of this are cars where rather than have positive and negative wires running to all electrical appliances in the car, they don't run a separate negative wire to each appliance. They just connect the negative connection of the appliances to the body work or chassis of the car and then connect the body/chassis to the negative terminal of the car's battery. The chassis earth/ground is providing an easy mechanism to connect the negative wires of all the appliances together. In earthing/grounding for electrical installations, the ground wire is not part of normal operation, it only carries current in a fault situation. And the goal is that it doesn't carry the current for a sustained length of time. The goal is to have a low impedance path to cause as much current as possible to flow to cause the circuit breaker to trip and disconnect power to the installation or part thereof, thus rendering it safe. There are a lot of terms relating to grounds and earth's and they mean different things in different situations. And it does become confusing.
Next video, can you delve into why groundING conductors are often smaller than the groundED neutrals that the go with? Thanks for the hard work you put into your channel!
the grounded conductor has to carry the entire circuit current indefinitely. the grounding conductor only has to carry the current long enough to operate the overcurrent protection in the event of a fault. therefore heat buildup isn't a factor.
Hi, Dustin. I am an electrician apprentince. I love your program and they are pretty informative. one question I would like ask is that are ground rods or ground plates able to complete the ground fault circuit? I guess not but not sure why, can you explain it? thank you.
Great explaination but for us computer geeks could you explain what, why and how to use orange sockets, those with two ground path. I use one path for ground casing of the socket and the other directly two its own rod in the ground to avoid noise for telecommunications equipments hook to computers.
Can you make a video on what you can do with a residential wireman’s license. As far as can we advertise ourselves on our vehicles 🚗 how can we find jobs for ourselves etc etc thanks love the info and videos been here for about 3 years now
When I worked in a commercial kitchen, we had a walk in cooler in a short hallway that also housed an electrical oven used for roasting directly across from the cooler's door. Additionally, this area was on a ramp thus the need to hold the carts we moved into the cooler. One day I pushed a metal rack against the oven and opened the door, the cart connected to the oven's outside frame and I completed the circuit opening the walk in door. As it turns out, the maintenance crew changed the plug to fit the appliance and didn't connect the ground. Eventually, the wire wore through the shielding, and energized the frame of the oven and the cart it was on. Not a fun day for me...
Why bond in the metal box with a jumper/pigtail since the metal ears of the receptacle are touching the metal box and the ground conductor that connects to the receptacle also is internally connected to those metal ears? So, in other words, why just run the ground conductor to the receptacle ground screw and the metal box will also be grounded because it touches the metal ears of the receptacle?
I was drilling holes through some old light fixture boxes to attach ground screws when I noticed the same thing. The light fixture was bonded to the box by simply installing it, so I didn't bother adding a pigtail. I would love to hear an answer to your question, because it does seem redundant and it's not like the receptacle is going to lose contact with the box.
DIY here that cares about doing things right. 1939 house, has a lot of MC/BX running all over. Frequently into plastic junction boxes (or even receptacle boxes) where it connects to NM cable without accounting for the grounding conductor. I hate it but I want to tear up as little as possible to fix it. When this happens in a plastic receptacle or switch box, is there an approved way to attach a grounding bushing to the BX so I can utilize the grounding lug and attach the grounding conductor from the NM to it? It seems the grounding bushings I see are all designed for circular knockouts which I don't have in most cases.
If I followed this correctly, my shop is not correct. Due to the pole barn construction, I used conduit throughout. I used 1/2 EMT and THNN wire, with metal handy boxes, etc. I wired it 15+ years ago. But I do not remember putting grounding pig tails to the metal boxes. I suspect although it looks like a proper application, I need to watch this video again, and make a couple corrections. I'm thinking that conduit could get lit up as well. Rod
I may be thinking of this wrong, but isn't the receptacle bonded to the box, which is bonded (through conduit) to the panel, which itself is grounded? the conduit provides your ground fault path
@@josephtobolski After watching the video again, I suspect you are correct. Seems this video involves a single metal box/etc. on a Romex/sheath, wired system. Thus the added bond. Rod
That is a code violation. The box needs to be bonded regardless of whether there is a device connected to it or not. They make self grounding switches and receptacles that are bonded to the already bonded box when you tighten the device screws. The point is that the box needs to be bonded even after devices are removed. Sometimes a box is just a junction and in that case there is no device but it needs to be bonded if it's metal.
Yes, but it’s good practice to run a bonding wire. The code also allows mc/ conduct to be used for bonding, but over time (especially conduit) connections get loose and then the ground is lost. Codes are minimum
@@jacobz3400 No, MC outer armor cannot be used as bonding. That's why MC has a ground wire inside of it. EMT can be because it is considered an effective ground fault current path. I am not sure who you are replying to because what the person above asked was about grounding the device and using that to bond the box. No one asked or mentioned about not running a ground wire. That would be an option with EMT, though, even though I would run a ground.
I always open my code book when watching your videos. I paid $120.00 for the "real" 2020 NFPA NEC book. And I brought it directly from NFPA. I can not find 250.4 in my book. Mine goes from 250.36 G to Part III 250.50.
I am a pilot, not an electrician. In pilot safety training, much emphasis is put on a "chain of mistakes." The rule is, one mistake will not kill you, but if a chain develops and is not broken, then you or others will die. If you break the chain at any point, then no accident will happen. I made the comment about metal electrical boxes in an effort to find the chain. For example, if I use the green ground wire and attach it to one green screw on the strap of an electrical outlet, and then use metal screws to attach the strap to the metal box, it will ground the whole box as well as other outlets in a 4 gang box. Now, something could go wrong, possibly years later, but I cannot see what the problem is. That is the reasoning behind my question.
So in accident theory, and particular in aviation safety, an aircraft crash or less serious accident is often caused by a number of different things going wrong, things that have been missed. It isn't like that in electricity installations.
commercial kitchens 3 phase motors like Hobart mixers 4 wire receps. 3 hots and a ground. mobile homes mostly have a sid-connect by meter, from there to the load center which is now a sub-panel, must have a 4 wire feeder, 2 ungroundeds 1 neutral and a ground and the neutral bus MUST be isolated from the cabinet.
I was hoping you would get into why we isolate neutral and ground in a subpanel (but that can be for another video) that confuses a lot of people - including me when I started out. Reminds me of the first time I had someone (a young job site helper trying to get in the trades) ask me why there's a ground AND neutral conductor and I used this scenario of a loose conductor in a piece of equipment to explain their specific purposes and I saw the light bulb moment when he seemed to grasp the concept. He kept coming back and asking questions that day I think he realized he maybe could learn this electrical stuff, I never saw him after that but I hope he did!
The reason that we isolate the ground and neutral in every panel that is load-side of the service disconnect, is that the neutral is meant to carry current under normal circumstances, and the equipment grounding conductor isn't. When there is an unbalanced load in the subpanel, the neutral carries the imbalance of current back to the source. If you bond neutral and ground in unnecessary locations, you create parallel paths with objectionable current on the EGC, the metal equipment housings, the building steel, the conduit, etc. You want the green wire and all the electrically dormant metal, to remain electrically dormant, unless there is a fault. Any intended current that has to flow on a zero-volt wire, should flow on the neutral. If not required by the NEC, do not bond neutral and ground. Keep these systems isolated, except where the NEC requires you to bring them together, which is at the main service disconnect.
@@carultch Error in this post. "current carries the imbalance back to the source." This should be "the neutral carries the imbalance back to the source."
Wondering if you can speak of two hots on one white, example one neutral being used by two 20amp breakers or one 20amp and a 15amp breaker. Thank you for your videos.
The mounting straps on receptacles and switches don't count as a ground, for metal boxes that don't otherwise have a ground in them? The circuits are wired up with Romex that has a ground wire in it.
Thanks, what is the point of the main service grounding rod then if the point is to complete the circuit? Not sure what having a rod in the ground is really doing
Your videos are Awesome! I do have a question: Do the Neutral and Ground wires always need to have separate bus bars in a main circuit panel or can they use the same bus bar?
Good stuff! Here’s an interesting topic I come across that no one can seem to answer the same. And that is how the current flows in systems using the literal earth as the return path such as a SWER (single wire earth return) system. Some say it literally flows in the ground from electrode to electrode. And others say electrons are simply pushed and pulled at both electrodes due to earth being an “infinite sink for electrons.” What is your professional take on this? How does the current actually flow?
At 10:02, you show the ground path go through the metal of the yoke. I know that the ground and the yoke have continuity. But, some folks say despite that fact the yoke and ground are the same and that the yoke connects to the box, that the ground has to be separately connected via pigtail to the metal box. Care to comment? Specifically, in a 14-50 receptacle. People run a ground pigtail that have potential for issue down the road because they say it's not enough to have grounding to the receptacle (which runs through the yoke and is mounted to the metal box).
It took a bunch of vids for me to learn that a breaker won't trip because the circuit went to Earth ground. Earth ground by itself won't flow enough current to trip a regular breaker. I always thought it would just trip if you touched a wire to Earth, but it won't. Dangerous.
The neutral is bonded to the ground ONLY at the main breaker panel - no where else, and NOT at any sub panels beyond the main breaker panel. The utility feeds the single phase home with *three wires** - two hots and a neutral. Overhead is usually #2 or 1/0 TPX from pole to the weather-head. It's up to the residential service to *derive* the safety ground. The pole mounted transformer has the system neutral bonded at the pole to the down ground. This is a safety ground. At First Energy we eliminated the spark arrester grounds and bonded all the pole pig neutrals (120-0-120 transformer secondary center tap) to the down ground. At the pole or pad mounted transformer the neutral is bonded to a ground rod; either a ground rod at the base of the pole OR a ground rod at the PAD transformer. This is mainly for a path to discharge lightning AND not a safety ground for the residence. Service ground is at least two means, water pipe, well head casing (if not municipal) and driven 8 ft rods or a combination of all. Some jurisdictions want two ground rods AND the water pipe ground tied together at a single point grounding block near the meter pan. By the way, the power line primary, say 7200 volts to ground uses a neutral for the return back to the substation. Typically there's a down ground on poles every 1000 feet all the way back to the substation. These grounds are for lightning protection ONLY. Retired Substation Engineer FE Ohio.
Apprentice here. MANY electricians believe that the ground rod is part of the current path. They refuse to not believe this, as they believe the current “wants to go to ground”. When I point out that that is not the case, they get defensive.
You haven't explained what the service ground is for the PAD transformer. You said there is a ground rod at the PAD connected to the neutral. My question to you then is: What do you intend the return path to be for a fault current originating in the residential property and back to the PAD? If it is not intended to be through the ground rods of the property and PAD, then it must be the neutral line from the PAD transformer to the property? Which means the property must create its own separated earth at the incoming supply end of the property. In which case, why bother with a ground rod at the property, except as a back up in case the neutral line from the PAD becomes broken? Is it true then every US residential property has an ground rod in addition to using the neutral from the PAD to the property as the return path for the fault current?
@@deang5622 The ground at the pad is to dissipate any lightning that may find it's way to the primary or secondary. In a single or three phase pad, the ground bonds the primary system neutral and the low side neutral at the same point. The same goes for a pole mounted transformer. Any fault current on the primary returns to the substation on the system neutral. A secondary fault returns to the secondary windings. The magnitude of the secondary fault current depends on: 1. Transformer impedance, secondary wire size and the primary fault current magnitude at the elbow feeding the transformer. This is usually at 12.47 KV, 13.2 KV or 4.16 KV. Primary fault current & transformer impedance can be determined by the utility. Based on that, you can calculate the secondary fault current at the meter pan. I use the EATON I Phone AP - fault current calculator. If it's over 10 kA then you need better breaker / load center to next level at 22 kA capability. Usually most residential situations are under 10 kA fault current capability. The load centers sold in the home centers are usually 10 kA rated.
@@sethtaylor5938 That is a long answer but you didn't actually answer my question. You said "any fault current on the primary returns to the substation in the system neutral." And : "A secondary fault returns to the secondary windings". Agree on both of those. But my question is what is the route taken by the fault current in the secondary circuit where the fault occurs in the residential property. It seems to me the answer is one of the following: 1. Along the neutral line from the property back to the secondary winding on the pad 2. Through the physical earth/ground using the grounding rods of the property and PAD Which is it, 1 or 2?
@@deang5622 The fault current on either leg of the 120 volts or across both legs of 240 in the residence is reflected through the transformer windings (through the transformer impedance) back through the primary neutral to the substation. The fault always goes back to the source. Grounds at the service equipment are there to ensure that the NEV (neutral earth voltage) doesn't go above 3 volts (NESC National electric safety Code) The lowest resistance back to the source (substation) is via neutral - meter pan - pad transformer - through the impedance of the transformer back to the substation. Ideally, grounds are for: safety (in event of neutral continuity break) and to carry away lightning charges, but not not fault current PAST the meter load center. That's why the electric service in the home is only supposed to have one common location where the inside neutral is bonded to a water pipe, well head and driven rod - a single point. So that's where inside faults are then *transferred* to the utility source. Remember, the electric supplies via: overhead triplex, two hots and a neutral or Underground two hots and a neutral. All fault current that flow outside of the residence is carried on the utility neutral.
The answer is obvious, but my question is, what exactly is the benefits, if any, to using metal boxes in a residential home? Seriously, I don't know of any. If there is any, I'd really like to know. Thanks 😊
Good video and good topic too! Question, Ive got into before, where a sub panel ( especially in another building or something) there's only a 3 wire run to the sub panel but has no ground wire with it, does putting down a ground rod do any good? And then I come across it a lot where the ground wire is terminated in the metal box only and not on the device, I assume that's not to code anymore doing it that way.
definitely not by the code.... mostly for the last case you mentioned; in case of a fault, the current might flow through the user who connected a charger to it
We had an ADU built two years ago in our backyard. It passed all inspections and overall appears to have been built extremely well. There was only one minor thing I noticed recently (which may be nothing at all, but I figured I'd ask because I like learning new things). When moving some things around in a cabinet in the kitchen I noticed MC coming out of a metal junction box that continues on and lands in a blue plastic box feeding a receptacle on the outside of the cabinet. I understand that the MC was used to protect the wiring in the cabinet area from possible damage, but I would have thought an electrician would normally land the MC in a metal box? Are you allowed to have MC land in a plastic box? Just curious. Thank you.
The answer seems pretty darn straightforward before actually watching-plastic isn't a conductor and so doesn't really pose a shock hazard if it's not bonded to earth. I guess we will see if I'm right haha
Great video thanks.i just need to know something i bought surface mount plastic box and it has an earth screw in it so before i install it i need to know if i need to add an extra earth thanks
Is this because you always want the ground-fault path to make it's way BACK to the main service panel? And that is why we don't bond neutral and grounding conductor at sub-panels? I know there is other reasons....I am blanking (2nd yr apprentice here)
@@mikenormandy9250 the reason for the isolation between the neutral and the equipment ground at a sub panel is because we want to direct path for fault current to flow. If the neutral is bonded to the EGC this creates a parallel path for the fault current to flow. We want that fault current to flow as quickly as possible to facilitate the over current protection device (circuit breaker) to clear the fault.
@@PatrickKQ4HBD This is not the reason we don’t bond the neutral at multiple points. The reason we don’t do this is actually to prevent objectionable current flow under normal operating condition. If you bonded the neutral at a sub-panel, the line to neutral circuits would use the grounding conductor as part of the circuit. We only want fault current to travel on the grounding conductor, so we bond neutral only at the main disconnect, service disconnect, or at the transformer, depending on the situation.
Dustin, I know I have installed a bunch of smoke detectors, but during taking an electrical exam, the city asked a bunch of questions about "distances from" and specific locations of them and I couldn't find any of that in the 2008 NEC codebook....yeah, that's right, Indiana still uses the 2008 NEC codebook. However, I have the 2020 codebook and it is no better in informing that information. So, my question to you is if the AHJ uses NFPA72 codes for that subject and you are not told to bring a NFPA72 codebook, how the heck are you suppose to answer any of those without being able to write down the code reference(s) to those questions? Can you make a video on smoke alarms/detector installation that references such code article and section references, if there are any. Maybe in the 3 hour testing session my eyes were so buggy I just couldn't see straight! Hahahahaa..... also..... what the heck does a few questions about solving a hypotenuse have to do with electrical work or code? Each question out of 100 questions are worth only 1 point each, but you have to have an 85% or better to pass. They seem, to me, intentionally place too many unrelated questions that also cause you to waste time on something not there. It seems like they just want you to keep spending money to test! Why not just put electrical code related questions only and charge $250 to take the test that if you are a real "qualified person" (according to Article 100) electrician it is a better way to collect some contractor money, and the fakes wont want to spend that amount of money anyway so it will scare them away. I don't think Electricians that have been a tested Master Electrician should have to test in any other city. Some cities respect that and allow reciprocal licensing. If you don't know what you are doing, the AHJ of the city can fail your inspection(s) or strip your license for good if your work isn't up to par anyway. Never had an Inspector complaint in the 46 years I have been an Electrician. I enjoy your videos very much, and I respect your opinion and experience. Keep up the good work.
