Purpose of Grounding Electrode System

[Adamjamma]

No problem... there was a whole lot of stuff being posted by certain companies about what was supposed to be in the new edition, especially arc fault and surge protection, that is just suggested for now, instead of required. Most of new changes were more words or in some cases where a comma went..lol...
Biggest changes were the requirement for almost every residential circuit, including lighting, to be on RCDs, and the changing of some of the fusing to tighten up the time of disconnect... one of the stupidest was a change in size for some stickers concerning RCD testing... They made the sticker required to be larger but no change in wording...lol

 

[mbrooke]

No problem... there was a whole lot of stuff being posted by certain companies about what was supposed to be in the new edition, especially arc fault and surge protection, that is just suggested for now, instead of required. Most of new changes were more words or in some cases where a comma went..lol...
Biggest changes were the requirement for almost every residential circuit, including lighting, to be on RCDs, and the changing of some of the fusing to tighten up the time of disconnect... one of the stupidest was a change in size for some stickers concerning RCD testing... They made the sticker required to be larger but no change in wording...lol

Be happy its all simply suggested. They should have kept the special exemption for RCDs. But then again who is to say X socket will have the same purpose 12 years down the road.

 

[daytonajim00]

What do you mean I float the neutral at a sup panel I thought everything needed to be bonded? Do I only bond at the main disconnect or do I bond everything?

We only bond (MBJ) neutral to EG's once at first means. With a seperate structure you establish another GE and the reason why is what I've been trying to examine this whole time. Actually it's already came up on the forums before I just found...

Someone previously said,

"Ok, I want to clarify something.......I understand by 08 code you have to run 4 wire to a seperate sub panel in a detached structure BUT my question is are you required to have a ground rod at the seperate structure also?????:-?:-?

One reply that I would like to highlight is as follows,

"Yes, every structure with more than a multi wire branch circuit has to be grounded with an electrode specifically for lightning and over-voltage;*see 250.4(A)(1) this is it�s purpose*& 250.32. The rod has nothing to do with the neutral at the separate structure though."

http://forums.mikeholt.com/showthread.php?t=120743

 

[romex jockey]

the old 250.32(B) differs from the new 250.32(B) , but a GES was required either way ,due to 'structure'.

a while ago, the structure debate revolved around lighting poles, ala 225.32 , which resulted in ex3

~RJ~

 

[Adamjamma]

"Yes, every structure with more than a multi wire branch circuit has to be grounded with an electrode specifically for lightning and over-voltage;*see 250.4(A)(1) this is it�s purpose*& 250.32. The rod has nothing to do with the neutral at the separate structure though."

http://forums.mikeholt.com/showthread.php?t=120743

does that mean you need to bond that ground rod or cee to the original structure with a number 4 or 6 wire buried in the ground? for equipotential reasons? I mean, you could be talking, on a farm, of buildings that are over a thousand feet apart so in my mind, treating them as separate buildings and separate services as the have been treated in past makes more sense...

 

[jaggedben]

The EGC is not run directly in the ground. It is run with the circuit conductors.

 

[daytonajim00]

does that mean you need to bond that ground rod or cee to the original structure with a number 4 or 6 wire buried in the ground? for equipotential reasons? I mean, you could be talking, on a farm, of buildings that are over a thousand feet apart so in my mind, treating them as separate buildings and separate services as the have been treated in past makes more sense...

No. The ground rods, like the ones on the main building, are for lightning and other foreign over voltages. They are connected to the subpanel and driven in the dirt for the separate structure. Does not matter the distance between structures. (250.4 says why we make a connection to earth)

On a different note, I may have brought in some confusion when talking about the GES as a whole. I didn't take in to consideration water pipe and building steel and the fact that we size them to 250.66. They way I was taught, we do this because they they run along with the electrical system and have the potential to become energized. We need to carry such fault back to the neutral. This example isn't ground (to earth) in the definitive sense yet we include it in the grounding electrode system.

I would like to make an illustration of the entire GES and am trying to make sure I have it right. Ground rods for lightning/overvoltages seem like a closed case. Somebody can correct me on water pipe and building steel as it pertains to 250.66 if I'm wrong.

Great conversation nonetheless.

 

[JPinVA]

does that mean you need to bond that ground rod or cee to the original structure with a number 4 or 6 wire buried in the ground? for equipotential reasons? I mean, you could be talking, on a farm, of buildings that are over a thousand feet apart so in my mind, treating them as separate buildings and separate services as the have been treated in past makes more sense...

You don't bond grounds on separate structures. However...keep in mind that they are connected...via the EGC...as well as via ground itself. This creates the following conditions:

1. A ground loop under normal conditions. This isn't a "source" current loop (which is usually a code violation, and is the reason why we don't bond EGC and neutral at a sub panel), but a result of the simple fact that two position on earth, particularly the greater the distance between them, are not the same potential. The EGC runs from panel to panel, and each panel is connected to ground. Ergo, current will flow between those points via the EGC. Not much in most cases...but some.

2. During a lightning event, the lion's share of the current will run to ground (GES) via the GEC of the building experiencing the event. But, depending on where the event occurs and the gradient delta between the buildings, some of this current will flow on the EGC between buildings. In fact, some could flow from ground (GES), up the GEC...to the ground bus, to the EGC, and back over to the other building's ground bus, to it's GEC, to it's GES. That said, keep in mind that for lightning pulses, wire inductance (as little as it may be for 60Hz source current) can become a significant factor for a lightning event. So things get kinda wonky. Bottom line is something runs along the line, but it's not a trivial calc. In my mind, I just realize "something" is there, and the experts have deemed it relatively safe.

The small current in (1) and the transient conditions in (2) are realities of our our "charged" world, and are acceptable states considering the main reason an EGC is carried between buildings. Ensuring a man-made ground fault in building two is cleared.

 

[tom baker]

These Art 250 sections are mostly overlooked, but they provide the performance requirements that grounding and bonding are required to accomplish
Start with 250.4
(A) is for grounded systems
1 tells us why we ground
2 is grounding to prevent an induced voltage build up from lightning
3 is bonding to make the low impedance fault current path
*** note the last sentance
4 is bonding non current carrying items

(B) is for non grounded, same as (A) but no system bonding jumper

So grounding is for lightning and line surges
Bonding is to create the effective ground fault current path

My best recommendation is to get the Mike Holt DVD on Grounding Vs Bonding. Please go to You Tube, search for Mike Holt grounding and look for some of his videos

Mike Holt once said many years ago, most information on grounding is wrong, and that still holds true. He has been responsible for getting many changes made to Art 250. If you are a new electrician, art 250 makes perfect sense, old electricians were taught wrong and carry too much baggage.

Examples
Electricity takes the path of least resistance
Water and electricity don't mix
We need to pull a 12 gage ground wire

Please look up the definitions of ground, grounded, earth...

Ideally the green wire would be called the Equipment Bonding Wire...

 

[daytonajim00]

These Art 250 sections are mostly overlooked, but they provide the performance requirements that grounding and bonding are required to accomplish
Start with 250.4
(A) is for grounded systems
1 tells us why we ground
2 is grounding to prevent an induced voltage build up from lightning
3 is bonding to make the low impedance fault current path
*** note the last sentance
4 is bonding non current carrying items

(B) is for non grounded, same as (A) but no system bonding jumper

So grounding is for lightning and line surges
Bonding is to create the effective ground fault current path

My best recommendation is to get the Mike Holt DVD on Grounding Vs Bonding. Please go to You Tube, search for Mike Holt grounding and look for some of his videos

Mike Holt once said many years ago, most information on grounding is wrong, and that still holds true. He has been responsible for getting many changes made to Art 250. If you are a new electrician, art 250 makes perfect sense, old electricians were taught wrong and carry too much baggage.

Examples
Electricity takes the path of least resistance
Water and electricity don't mix
We need to pull a 12 gage ground wire

Please look up the definitions of ground, grounded, earth...

Ideally the green wire would be called the Equipment Bonding Wire...

Yes!

 

[jaggedben]

No. The ground rods, like the ones on the main building, are for lightning and other foreign over voltages. They are connected to the subpanel and driven in the dirt for the separate structure. Does not matter the distance between structures. (250.4 says why we make a connection to earth)

On a different note, I may have brought in some confusion when talking about the GES as a whole. I didn't take in to consideration water pipe and building steel and the fact that we size them to 250.66. They way I was taught, we do this because they they run along with the electrical system and have the potential to become energized. We need to carry such fault back to the neutral. This example isn't ground (to earth) in the definitive sense yet we include it in the grounding electrode system.

I would like to make an illustration of the entire GES and am trying to make sure I have it right. Ground rods for lightning/overvoltages seem like a closed case. Somebody can correct me on water pipe and building steel as it pertains to 250.66 if I'm wrong.

Great conversation nonetheless.

You keep saying 'ground rods for lightning'. It's not that specific. Any electrode performs the same function, and there are multiple functions that grounding performs, and multiple options for electrodes. All electrodes at a building are required to be bonded together so there's no potential between them. All the electrodes then perform the same function. If a metal water pipe happens to be among them, it gets wrapped in.

 

[JPinVA]

YAll electrodes at a building are required to be bonded together so there's no potential between them. All the electrodes then perform the same function. If a metal water pipe happens to be among them, it gets wrapped in.

Keep in mind that bonding to the water pipe is required in code regardless of whether it meets the criteria for an electrode. So, your first statement is correct. Your second statement is correct, but might not apply to the water pipe (depending on whether it meets the criteria of an electrode or not). Your third statement is interpretatively correct as "among them" can be among electrodes (if the water pipe meets the criteria) and will always be "among them" (as the water pipe must be bonded).

 

[jaggedben]

Keep in mind that bonding to the water pipe is required in code regardless of whether it meets the criteria for an electrode. So, your first statement is correct. Your second statement is correct, but might not apply to the water pipe (depending on whether it meets the criteria of an electrode or not). Your third statement is interpretatively correct as "among them" can be among electrodes (if the water pipe meets the criteria) and will always be "among them" (as the water pipe must be bonded).

Sure, agreed. In short, the water pipe must be bonded, and may or may not also be required to be treated as an electrode. It may be only one thing or it may be two things.

The point I was trying to make was a more general one. There are lots of electrodes that qualify to be part of a GES, and there's more than one purpose, function, or benefit to having a GES. There were some too-specific comments that were irking me.

 

[kwired]

No. The ground rods, like the ones on the main building, are for lightning and other foreign over voltages. They are connected to the subpanel and driven in the dirt for the separate structure. Does not matter the distance between structures. (250.4 says why we make a connection to earth)

On a different note, I may have brought in some confusion when talking about the GES as a whole. I didn't take in to consideration water pipe and building steel and the fact that we size them to 250.66. They way I was taught, we do this because they they run along with the electrical system and have the potential to become energized. We need to carry such fault back to the neutral. This example isn't ground (to earth) in the definitive sense yet we include it in the grounding electrode system.

I would like to make an illustration of the entire GES and am trying to make sure I have it right. Ground rods for lightning/overvoltages seem like a closed case. Somebody can correct me on water pipe and building steel as it pertains to 250.66 if I'm wrong.

Great conversation nonetheless.

Others have touched on it, but water pipe that is 10 feet or longer in the earth is an electrode. Building steel that has at least one section that has at least 10 feet of contact with earth (with or without concrete encasement) or is bolted to footing that has CEE within it is also an electrode. Isolated building steel that isn't likely to become energized isn't required to be bonded to at all, good example of that is steel beam sitting on wood or even with limited contact on concrete that has essentially no continuity to earth and has no electrical equipment in contact with it.

Water pipe electrode requires supplemental electrode - only because of the possibility of water pipe being changed to non metallic piping, otherwise water pipe is usually a better electrode than a ground rod, which is typical to be used as the supplemental electrode. If you do have building steel or a CEE then they supplemental to the water pipe and a rod is not required.

Qualifying water pipe, building steel or CEE all typically are lower resistance electrode than a pipe or rod electrode - they all have greater surface area in contact with the earth.

 

[StarCat]

ON the Matter of " Misunderstandings..."

ON the Matter of " Misunderstandings..."

IT technically- and I disagree. In hospital ORs all EGC are bonded together- Norway made the mistake of not bonding between structures resulting in fires. Meaning structure 1 would have an A phase ground fault and structure 2 might have a B phase fault creating 230 volts potential between structures. A beautiful idea ruined again by what again I think is a global misunderstanding of what is grounding and what is bonding.

As such RCDs are now recommend as the system is basically a TT at most times. TT systems need grounding electrodes to clear a fault btw.

If you take a serious look at what Eric Dollard has written and spoken about in the recent past, it should come fully clear that there are some very dangerous Engineering trends being implemented in the grid system that essentially constitute an even more dangerous misunderstanding and willful ignorance of what is safe and what is not, and also what works and what definitely is going to lead to major problems that are very easily demonstrated.
There is a great deal more that can be said on the subject, but its critical that learned people start questioning whats going on at large and doing the critical research so as to understand the insanity of it, rather than just going along with dictates from on high that are ill advised.
The mistakes being made are large and will lead to even larger problems. The ignorance of just how dangerous these practices are, is going mostly unnoticed is an even worse " sign of the times."

 

[GoldDigger]

These Art 250 sections are mostly overlooked, but they provide the performance requirements that grounding and bonding are required to accomplish
Start with 250.4
(A) is for grounded systems
1 tells us why we ground
2 is grounding to prevent an induced voltage build up from lightning
3 is bonding to make the low impedance fault current path
*** note the last sentance
4 is bonding non current carrying items

(B) is for non grounded, same as (A) but no system bonding jumper

So grounding is for lightning and line surges
Bonding is to create the effective ground fault current path

My best recommendation is to get the Mike Holt DVD on Grounding Vs Bonding. Please go to You Tube, search for Mike Holt grounding and look for some of his videos

Mike Holt once said many years ago, most information on grounding is wrong, and that still holds true. He has been responsible for getting many changes made to Art 250. If you are a new electrician, art 250 makes perfect sense, old electricians were taught wrong and carry too much baggage.

Examples
Electricity takes the path of least resistance
Water and electricity don't mix
We need to pull a 12 gage ground wire

Please look up the definitions of ground, grounded, earth...

Ideally the green wire would be called the Equipment Bonding Wire...

Just a note on impedance and lightning associated currents: once you get past the resistance of the rod or other electrode and the associated wires, including the contact resistance, the impedance of the earth path between buildings will be lower (by far?) than a typical EGC wire because the wire will have substantial inductance at lightning frequencies but the earth will be a very large effective diameter conductor with correspondingly lower inductance.

Sent from my XT1585 using Tapatalk

 

[romex jockey]

If you take a serious look at what Eric Dollard has written and spoken about in the recent past, it should come fully clear that there are some very dangerous Engineering trends being implemented in the grid system that essentially constitute an even more dangerous misunderstanding and willful ignorance of what is safe and what is not, and also what works and what definitely is going to lead to major problems that are very easily demonstrated.
There is a great deal more that can be said on the subject, but its critical that learned people start questioning whats going on at large and doing the critical research so as to understand the insanity of it, rather than just going along with dictates from on high that are ill advised.
The mistakes being made are large and will lead to even larger problems. The ignorance of just how dangerous these practices are, is going mostly unnoticed is an even worse " sign of the times."

Eric Dollard looks interesting Star.....~RJ~

 

[mbrooke]

If you take a serious look at what Eric Dollard has written and spoken about in the recent past, it should come fully clear that there are some very dangerous Engineering trends being implemented in the grid system that essentially constitute an even more dangerous misunderstanding and willful ignorance of what is safe and what is not, and also what works and what definitely is going to lead to major problems that are very easily demonstrated.
There is a great deal more that can be said on the subject, but its critical that learned people start questioning whats going on at large and doing the critical research so as to understand the insanity of it, rather than just going along with dictates from on high that are ill advised.
The mistakes being made are large and will lead to even larger problems. The ignorance of just how dangerous these practices are, is going mostly unnoticed is an even worse " sign of the times."

Any links that you think are worthwhile? I am curious what more you have to say, you sound very well informed.

 

[jumper]

this?

~RJ~

Nope. Motorola R56, cell tower wiring, 500+ pages, not for the faint of heart.

 

[mbrooke]

Nope. Motorola R56, cell tower wiring, 500+ pages, not for the faint of heart.

Glad to see you back and posting