Why? do we drive ground rods at detached buildings?

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[@Jimdandy1958]

It would seem to me that if the first grounding electrodes are capable of dissipating static electricity on the main house equipment by means of the EGC wire attached to it, then when a directly connected wire extends to the outbuilding it would be able to dissipate static there as well. If not, why not. I like that you said the electricity takes the path of least resistance "BACK TO THE SOURCE" that's the important part. Traveling down the ground rod at the house, through the earth to the ground rod at the pole, then up the pole to the CENTER TAP of the transformer is definitely NOT the path of least resistance and will not throw the breaker and clear the fault. Instead, that is accomplished through that egc/neutral bond at the main panel. The microsecond surge of voltage on our equipment surfaces induced by nearby lightning is trying to get back to its source as well... The earth. That is accomplished by the ground rod. Lightning is nothing more than static electricity on a massive scale. Lastly it needs to be emphasized that you mentioned that the grounds and neutrals remain separated at the outbuilding. The grounding rod at the outbuilding is NOT connected to neutral. Only the ECG(equipment grounding conductor). The neutral is only connected to the rods at the main house.

[@trustnoone4328]

Great explanation of why we need to install ground rods on a detached garage or shed .

[@lesterwatson8519]

The ground field or ground rod at the second structure also enhances the ability of the frame ground or safety ground of any thing receiving power from the circuit by make a person touching the frame of that piece of equipment relatively the same potential as the frame of the equipment except at a higher impedance therefore providing more protection for them.

[@amorykin]

I have just a general ground rod installation question about depth. Must the ground rod connection and top of the rod be buried, or do you leave it sticking out above the surface of the ground? My other question is, I'm going to be running a hundred amp 2-2-2-4 underground to a detached garage from a 200 amp panel. If I use 1-1/4 or 2" PVC Schedule 40, do you need to attach the conduit to the wall before it enters my house? I asked this because I see this all the time on houses and there's no conduit straps to the wall. I guess you need to also consider Frost expanding and Contracting the conduits up and down I don't know if there is a slip sleeve conduit for this application and this size of conduit. Love your videos on the first time viewer, and lifetime learner! I worked as an electrician for years wiring homes and even some commercial work with an electrician, but honestly I've never done underground. Go figure.

[@tedlahm5740]

Clear concise information, as usual coach.

[@mrcryptozoic817]

Oddly, I did it almost right by accident. I had an old school solar panel (60w) that (obviously) needed a ground so I put one rod in, actually very near (within 2 feet) of the well to power a 20v DC pump. And another (1) 60 feet away, for the cabin panel which was powered by a generator. The shed is not a sub-panel to the main cabin; it's like a power pole. Four years ago I upgraded to 3 panels with charge controller and inverter and ran the solar to the inverter then to the cabin, but I left the grounding wiring alone. I grounded every chassis to the shed rod. (AC current doesn't flow back to the shed) however. There is AC current available there because the inverter has an AC outlet built in. And its frame is grounded to the shed rod. Didn't know I need two rods at each location, but it has worked flawlessly for the 5 years since the panel and AC upgrades. So the neutral wire has at least 3 paths it can take for the circuit (cabin ground, shed ground or, if generator then the floating neutral built in to the generator. So with the shed ground rod so close to the well, does it still need a second grounding rod?

[@spelunkerd]

When I built my greenhouse I carefully studied code requirements, including the American version of ground rods for detached buildings. So before I poured the concrete I reasonably put in a ground plate at 24" below the bottom of the concrete. I had two circuits in the greenhouse that are fed by breakers inside the house, with neutral and ground lines fed back to that main panel. My Canadian requirements were not very well written but there was a conflict in some of the paragraphs, where they specifically say that all ground rods for a system need to be interconnected. When the inspection was done, the only thing that failed was my ground plate. I was required to disconnect the copper ground plate wire right at the floor, with no connection to the metal frame of the building and no connection to circuits. My remarks about lightning were acknowledged but the frame of the greenhouse is anodized aluminum so he said it wouldn't help much anyway. I believe the requirement for a single ground system is to reduce the likelihood of eddy currents within the ground system, that might trip rcd's etc. So, for Canadians, check with your inspectors....

[@anthonyelectric6045]

Perfect explanation 👍.

[@Grunt49]

Thank you❤

[@MrKen59]

Thank you

[@busnorth]

Asked this question before with no response. A trailer house with a meter and main swich out side the trailer house. It's bonded and grounds. Box in trailer with main swich not bonded. Trailer panel feeds large out building sub panel 220 volts not bonded with 4 wire grounded back to meter box. No foundation like trailer house . Should there be ground rods at the out building?. It's 25 feet from meter and in town. The way I read it, all grounding is to be done at the meter per trailer house.

[@93FORDMUSTANG]

Im in the process of building my first home. In the process of wiring. Would i be able to email you?

[@stephenkennedy6358]

I'm pretty sure that the ground rods are utilized by whole house surge suppressors also.

[@bennypena1629]

Boom!

[@mehill00]

But the idea is that the fact that the garage and house are detached from one another is assumed to mean that, other than the 4-wire to the garage sub-panel, there is no other means of discharging between structures (e.g., no common plumbing). So if the secondary structure is struck by lightning, we’d like to isolate the surge somewhat and not have it attempt to discharge through the conductors in the 4-wires between the panels. Right? This suggests to me that in large structures (very big houses, apartments, and commercial facilities) that there are probably regulations/best practices on driving ground rods at multiple points around the building to help localized the lightning damage and bleed off less dramatic static electricity. Is this so? Of course the bigger the building the more the electrical needs tend to increase, so it’s natural to have sub panels in different “wings” anyway, but under what circumstances must the sub-panel in a single large structure be grounded with ground rods? Just curious. Thanks for the video!

[@wim0104]

big commercial buildings get a ring of bare 3/0 copper around them, bonded to the slab, and the steel columns

[@5stardave]

What if you didn't put in a sub-panel? You just ran a line out with a string of outlets?

[@wim0104]

without subpanel, the code does put the limit at a single multiwire branch circuit, afaicr...

[@lesheinen6116]

This has always puzzled me.......If electricity wants to go back from where it came from, how does it know where it came from? And how could the path of least resistance possibly be greater in the grounding rods located at the meter loop than the resistance to where it came from? I always follow the code but do not always understand the rational behind the requirements.....These being two of them.

[@jaromirandel543]

Because if both are connected, there is the same potential. And no difference in potential means no voltage between objects.

[@JC-ed7pt]

Coach! Is this a code requirement?

[@sigcrazy7]

250.32 Buildings or Structures Supplied by a Feeder(s) or Branch Circuit(s). (A) Grounding Electrode. Building(s) or structure(s) supplied by feeder(s) or branch circuit(s) shall have a grounding electrode or grounding electrode system installed in accordance with Part III of Article 250. The grounding electrode conductor(s) shall be connected in accordance with 250.32(B) or (C). Where there is no existing grounding electrode, the grounding electrode(s) required in 250.50 shall be installed. The exception is when there is a single circuit, or a MWBC going to the detached structure.

[@phillippearce9680]

👍

[@BufferStuffBuddha]

Why do you always see people argue that ground rods are not for lightning strikes?

[@jkbrown5496]

Strictly speaking, the ground rods are for induced currents from near-by lightning. A direct strike even at the service entrance is likely to melt everything and cause.a fire. But induced currents, from the EMP of the lightning or if you had a big motor, run on the line and dissipate. But if they hit an open switch, i.e., high resistance, the voltage rises and it can exceed the insulation ratings and cause arcs. The resistive path from the building ground rods to the transformer ground rods caps the voltage rise on the bonded neutral/equip ground and gives a dissipative path for the induced current. Building wiring is just a huge coil of wire hanging in the air picking up electromagnetic radiation which induces currents, those need to be dissipated and always have a path so the "infinite" resistance of an open doesn't cause a high "arcing" voltage.