I'm seeing Mike's battle

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mbrooke

Batteries Included
Location
United States
Occupation
Technician
I'm now officially seeing what Mike had to battle with in the last 40 years of his career, and I applaud him for standing strong in gale force winds. Screen shot of a new book publication, used in teaching students:
 

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drcampbell

Senior Member
Location
The Motor City, Michigan USA
Occupation
Registered Professional Engineer
For every YouTube video pointing in the right direction, there are three others pointing in the wrong direction and thirty others that are incomplete or incomprehensible.

I did enjoy Mike's video where he deliberately created a 120-volt-to-Earth fault, demonstrating that there wasn't enough current to clear the breaker and measuring step potential. But I don't think I would have staged that demonstration in street shoes; I think I would have insisted on firefighter's boots with guaranteed dielectric performance.
 

__dan

Senior Member
Grounding, is a listed conductor from point A, where you are , to point B, the source overcurrent protective device, which provides a required "effective fault clearing path back to the source" to facilitate the fault clearing action of the protective device.

"Grounding Conductor" must be of a type listed in 250.118. The Earth itself is not a listed grounding conductor. Grounding typically means there exists the required effective fault clearing path back to the source.

Earth Grounding, is a listed conductor from point A to point C, the Earth electrode. Where required to be installed, the code rules for Grounding Electrode Conductor are far stricter than the rules for grounding or bonding. The Earth is assumed to be a giant zero impedance common busbar, but in practice, there is some earth resistance between you and the giant common busbar. Earth resistance can create voltage differences between points under conditions of current flow, which is mitigated by the installation of required bonding, grounding, and earth grounding paths.

Where requirements exist, if it can be shown that the building steel substantially connects all the way back to the rebar in the concrete footings, connecting to the building steel may meet the requirements for an "Earth Ground".

Bonding is the interconnection of exposed metal parts to eliminate voltage potentials between them.

(it needs to be rewritten somehow)
 

gadfly56

Senior Member
Location
New Jersey
Occupation
Professional Engineer, Fire & Life Safety
OK, so what, exactly, does running a wire from the panel to a pipe in the ground actually accomplish? I've seen the the MH video where he winds up driving a 50 foot ground rod and even with two(?) more rods in the mix still can't get a fault clearing current back to the panel.
 

mbrooke

Batteries Included
Location
United States
Occupation
Technician
OK, so what, exactly, does running a wire from the panel to a pipe in the ground actually accomplish? I've seen the the MH video where he winds up driving a 50 foot ground rod and even with two(?) more rods in the mix still can't get a fault clearing current back to the panel.

IMHO not much I think.
 

Gary11734

Senior Member
Location
Florida
Mike is smart.

Where did Mike go to nudge the industry besides a classroom? The Code.

There are many books out there, but the code will have the most influence on the industry.

You will always have palm readers and fortune tellers.

The insurance companies run the place, and that is why the Code rules.
 

tom baker

First Chief Moderator
Staff member
I will say the NEC is much better now then when I started 40 years ago. Mike Holt once said if you are old I can't teach you grounding you carry too much baggage.
I suspect it will never happen but the term EGC should be EBC. Again, Mike Holt, most of grounding is really bonding.
And I note we all use the term ground to mean anything (what color is it and what does it do, MH) So a lot of the issues and misconceptions are our own fault, IE what size ground for a 200 amp service.
"We have met the enemy and he is us" POGO
 

JPinVA

Senior Member
Location
Virginia
OK, so what, exactly, does running a wire from the panel to a pipe in the ground actually accomplish? I've seen the the MH video where he winds up driving a 50 foot ground rod and even with two(?) more rods in the mix still can't get a fault clearing current back to the panel.

We live in an electrically charged world where things become "charged" from sources other than POCO power. It is these charges that ride the panel GEC to "ground". Not so much because those charges "go" to ground (as direction is not relevant), but because the grounding reservoir of charges swamps the house by many order of magnitude. This prevents the build up of potential on the bonded parts as they find equalization with the ground. And it provides a path for transient equalization...from potential impressed on the bonded parts from things like lightning.

Although POCO power will also interface with the ground, it is using that ground as a path back to the source. And as we've noted, this path is seldom sufficient to trip the breaker...but is sufficient to kill someone. Hence, the battle. A simple earth ground will NOT protect from a house fault of POCO power. But we still need that ground to help take care of the many other potentials mother nature throws our way.
 

__dan

Senior Member
The Earth is a reference point in the code rules. Nothing more or less. Electrical systems require be attached to the Earth, but only as a reference point. The Earth would supply the point of zero voltage.

In power circuits, metal can form a capacitor with the Earth, maybe parts of an antenna. In power circuits that effect would be something to be avoided or mitigated where found.
 

gadfly56

Senior Member
Location
New Jersey
Occupation
Professional Engineer, Fire & Life Safety
We live in an electrically charged world where things become "charged" from sources other than POCO power. It is these charges that ride the panel GEC to "ground". Not so much because those charges "go" to ground (as direction is not relevant), but because the grounding reservoir of charges swamps the house by many order of magnitude. This prevents the build up of potential on the bonded parts as they find equalization with the ground. And it provides a path for transient equalization...from potential impressed on the bonded parts from things like lightning.

Although POCO power will also interface with the ground, it is using that ground as a path back to the source. And as we've noted, this path is seldom sufficient to trip the breaker...but is sufficient to kill someone. Hence, the battle. A simple earth ground will NOT protect from a house fault of POCO power. But we still need that ground to help take care of the many other potentials mother nature throws our way.

So, by your explanation, if I had no electric service to my house of any kind, I'd still have to ground the rebar in my foundation?
 

Gary11734

Senior Member
Location
Florida
We live in an electrically charged world where things become "charged" from sources other than POCO power. It is these charges that ride the panel GEC to "ground". Not so much because those charges "go" to ground (as direction is not relevant), but because the grounding reservoir of charges swamps the house by many order of magnitude. This prevents the build up of potential on the bonded parts as they find equalization with the ground. And it provides a path for transient equalization...from potential impressed on the bonded parts from things like lightning.

Although POCO power will also interface with the ground, it is using that ground as a path back to the source. And as we've noted, this path is seldom sufficient to trip the breaker...but is sufficient to kill someone. Hence, the battle. A simple earth ground will NOT protect from a house fault of POCO power. But we still need that ground to help take care of the many other potentials mother nature throws our way.

Jp, is your conclusion this is about protecting POCO equipment from lightning strikes and that is about it? Once grounding gets out of my section of the code, I put a blinder on. I don't need to be any more confused than I am already.
 

Adamjamma

Senior Member
So, by your explanation, if I had no electric service to my house of any kind, I'd still have to ground the rebar in my foundation?

Actually, due to a simple action that happens within the concrete foundations, the rebar is actually grounded without the need of a ground rod. Concrete is not water proof, and so any time it has moisture around it, that moisture wicks to the items within it, eventually getting to the items inside the structure, but at the same time, helping bod the metal rebar to the ground potential around the building.
This is why the industry is starting to recommend those debonding tile sheets that you see in use in many areas, that are a rubber compound and you apply them to they concrete, then apply the tiles to them, though the industry pushes more about the waterproofing abilities of those sheets. They actually stop much of the moisture and gases from coming through the earth to the building as well. Thus the tiles in a basement do not feel damp in the mornings, and, one study so far as said, but not been proven by other studies yet, that the use of the sheets actually cuts the shock potential. Which is why so many of us in the Caribbean are watching for these studies. We know our customers walk around their homes barefoot, unplugging and plugging in electrical devices and complaining about shocks. So, we are looking for ways to help them. If a tile backer on a roll can help, why not??
But, if you look at the codes: The rebar in the foundation can be used instead of using a Ground Rod.
 
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