Grounding, System and Equipment [250.4, 2020 NEC]

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[TrendyStone]

These videos are fantastic. I’m an engineer and spent plenty of time on math, equations and story problems (bookwork) and not nearly enough time on practical real-world examples. These videos help fill the gap.

[thomasmateo]

thanks Mike for your video. I have been working electricity in ny for 5 years, I am very grateful, with my progress thanks to your video I hope God gives you a long life. thank you Mike

[pl]

I really enjoy and understand your explanation. It took me a few jobs to figure out that this is really what I love "ELECTRICITY". I'm 35 years old now but I hope one day I am as good as you sir. Many blessings for you and your family.

[Ibrahim-tvrv]

Thanks for making these videos free, hope you add more about pv systems grounding

[SURRYHOUSE]

thank you brother for what you do. 30 years in trade and still learning something new every day.

[ryanjourneymanwireman]

These pow wow sessions you do are so easy to watch and are very educational.

[dero]

Mike, I was having a conversation with someone on my job and we ran into an unspecified area in the Nec (2023). The question is are the wires feeding the primary of a transformer (served from a switch board) considered branch circuits or feeders? Transformers have primary ocpd, so that, for the sake of argument, is your final ocpd. The secondary is a separately derived system, so that leaves the primary windings to be the final part of the system. Nec 2023 art 100 has 5 types of branch circuits. The one that stood out to me was individual branch circuits. This states that there are branch circuits that supply utilization equipment. I would say a transformer isn't utilization equipment because it doesn't use electrical energy as power but only to transform voltage (minus eddy currents and hysteresis). Am I missing something here or does the code just leave this out?

[eddieo]

Mike I have a question. If you use grounding bushings on the pipe from the meter to panel . Do you put the or include the ground wire from the meter ground rod and make it one loop .or just ground the meter box to the ground rod .

[Architekt]

This video was so helpful in understanding grounding - thank you!

[krakenwoodfloorservicemcma]

that was one nasty lightning strike, Awesome video.

[thetruthexists]

I'm a PV electrician. Wondering if you can help me understand this because it seems like what you've said about driving ground rods is contradictory..so on the one hand if you have a remote building you need to be driving an auxiliary ground rod at the building (for induced voltage by lighting) but you've said you shouldnt be grounding at 2 different points because of the potential for electric going up one ground rod, through your equipment and down the other?
And so, we don't drive ground rods for PV arrays on buildings anymore but would this mean we should be driving ground rods at ground mounted arrays? That would seem silly after hearing you talk about driving rods at light poles. Appreciate any clarification! This issue has been bothering me for some time.

[Orgakoyd]

Hi, Mike. Firstly thanks for all your videos. Especially the ones regarding grounding, they are among the few voices on the internet that explicitly explain what grounding is for and ISN'T for!

I have a question. In the picture at the beginning of this video showing the transformer, let's say it was a dry type transformer inside a building for the purposes of obtaining a different voltage for some branch circuit (lets say to step up 240 to 480 for some equipment that needed it). If this transformer was fed off of a breaker from the main breaker panel where the main EGC is bonded to the incoming neutral provided by the service entrance, could you just run 4 wires (3 phases and the EGC) to supply the transformer, connect the EGC to the enclosure, and also connect the X0 terminal of the Wye secondary and the outgoing EGC to this point on the enclosure, without actually having a secondary gorundED connection to the steel column with the GEC shown in the picture? My logic here being that the incoming EGC supplied to the transformer from the main breaker panel is groundED by the utility wires coming into the building, so no need for a second earth electrode at the transformer inside the building right? In case anyone is confused I am NOT suggesting not having the SBJ that connects X0 to the EGC, just not having the GEC.

[cristinaaguilar]

Thanks Mike you are the only one I truly understand

[ironman]

I’m confused. You stated it doesn’t matter how big the system is it’s always a #6 yet the GEC is required to be sized based on service wire size? Is this just for a rod electrode?

[Ed-uueo]

Mike at minute 2:00 can I get rid of the supply side bonding jumper and instead use a main bonding jumper in the panel? Is this an option?

[dandearman]

Hello Mike. Without the ground connected to the secondary of the transformer the system ends up acting like a big capacitor. I'm sure you know a capacitor is two metal plates separated by an insulator which is what you would have in your electrical system. One plate of the capacitor is all of electrical conductors the transformer is feeding and the other plate is the panels, conduits and the enclosures separated by an insulator, the plastic coating on the wires and insulation between motor and transformer windings. So without the ground, the wiring has the potential to charge up just like a capacitor but with the ground connected secondary the potential should only ever get as high as the phase to ground voltage.

[dans]

Thank you very much for your time dedicated to improve the knowledge of random people from internet. I have a question about inverters. The shield is suppose to be conected on both sides, drive and motor, and thus create an alterate path for the current. This is not a problem for safety?

[garfieldwood]

16:37 Eric's statement regarding lightning strikes being ~1MHz: "takes about a millisecond" should say "1/4 microsecond"
assuming it is a 1MHz SINE wave. If so the volt peak occurs in 1/4 microsecond or second - 4000 times faster.
A lightning strike is more like a square wave pulse; so, the time period from 0 volts to strike voltage is far quicker than that.

[SpybottleMessuage]

Look at the question I have: I studied the Electricity Apprenticeship in 2005-2008. The Code got changed in 2012, 2017 and 2020. Now, I have the plain simple question. The COMMERCIAL CAFETERIA, as like McDonald's, has the MDP panel, grounding electrode with the ground rodes driven into earth, and.... If the blue print has the plumber pipes to be bounded to the grounded electrode...if it should be 250.66 table or 250.104 Table? What the size of the attachment must be installed, the required 2/0 max Copper from pipes to the outside grounding electrode conductor? Look at, the Commerce Kitchen has a lot of water related appliances, as like the dishwasher, the sinks, the water heaters, the water filtration stations, so, it MUST BE GROUNDED. But if the water pipes from outside the building have NO DIRECT CONNECTION TO EARTH as like minimum 10 feet bare metal - the water pipes are the plastic, and even the water collector in a mile away may be the metal, the feeding pipes are the white plastic. So, my question, if it MUST BE 3/0 or 2/0 size of the bonded to the grounding electrode conductor from tye water pipes attachment, or it may be concerned the need to be bounded at tye copper pipes inside the building with the only number 6 copper, or number 4 aluminum?! So, the question is the need to attach the copper pipes to the GROUNDING ELECTRODE CONDUCTOR WITH ITS SIZE dependable on the service phase conductor size, or tye appliances must be bounded just by the #6 AWG at rye points of their installations ?!! What the main reason in that?
I may woundering if the #6 or even #4 wire may have the "taps" - or it MUST be service size grounding electrode conductor SIZE of the building frame.
Before 2012 it was easier, but the later time the Nation Security abuse began to do complication in the clear things making special access to the plain NEC. Look at, it foreign country might want to begin their introduction of the business, and the foreign builder might entering the market building the new constructions for the competitors of the US, how they will be know the right NEC installations?!! The Military Fort troublemakers just created the problems in such questions.
I am just beginner in tye Trade, but I Need to have the answer.

[mahadihasan]

Sometimes, I wonder the selection process of IEC grounding method, one that I see in your graphics resembles TN-S system. But IEC proposes several other methods TT, TN-C-S. Also to add to my confusion resistance grounding and reactance grounding?