Purpose of GEC

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wawireguy

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I just realized that I really don't understand what the GEC does. Does it act as lightning protection? #6 min for ground rods seems rather small for that. Does it "equalize" something so that lightning doesn't want to hit that point? Does it have something to do with the POCO transformer feeding the service? Seems like I should know the answer to this but I'm unclear on this..:confused:
 
Here is what the NEC has to say about the funtion of grounding of systems.

"(1) Electrical System Grounding. Electrical systems that are grounded shall be connected to earth in a manner that will limit the voltage imposed by lightning, line surges, or unintentional contact with higher-voltage lines and that will stabilize the voltage to earth during normal operation."

Chris
 
wawireguy said:
I just realized that I really don't understand what the GEC does. Does it act as lightning protection? #6 min for ground rods seems rather small for that. Does it "equalize" something so that lightning doesn't want to hit that point? Does it have something to do with the POCO transformer feeding the service? Seems like I should know the answer to this but I'm unclear on this..:confused:
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Raider1 provides the NEC 's view on grounding. Its not only for lightning or surges, but the GEC system provides a zero reference point as to where "ground " is. Everything in the residence is bonded together so that everything is at the same potential and any time. I am including a reference on single point grounding that provides additional information.

http://www.csemag.com/article/177624-rounding_Points_Single_or_Multi_.php
 
wawireguy said:
... #6 min for ground rods seems rather small for that.....:confused:
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Actually, that is #6 max for a ground rod. Since a ground rod is limited by its design to the amount of current it can dissipate, using anything larger is a waste of resources.

While the Code does not prohibit using a larger conductor than a #6, that is the max size required.
 
kbsparky said:
Actually, that is #6 max for a ground rod. Since a ground rod is limited by its design to the amount of current it can dissipate, using anything larger is a waste of resources.

While the Code does not prohibit using a larger conductor than a #6, that is the max size required.
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Hmmm... I believe wawireguy had it right. #6 is the smallest size you can use. Therefore it is the required minimum size.
 
Ummm ... nope, guess again. And then read section 250.66(A):

Connections to Rod, Pipe, or Plate Electrodes. Where the grounding electrode conductor is connected to a rod, pipe, or plate electrodes as permitted in 250.52(A)(6), that portion of the conductor that is the sole connection to the grounding electrode shall not be required to be larger than 6 AWG copper wire ....
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You can use a #8 wire on a smaller service if you want to. However, there are other rules about physical protection if you do.
 
bob said:
but the GEC system provides a zero reference point as to where "ground " is. Everything in the residence is bonded together so that everything is at the same potential and any time.
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This simply isn't true.

Just take a meter out there and see for yourself.

Grounding and bonding basically protects the buildings wiring system, you know, a way to trip the breaker.

As far as acting as lighting protection, good luck, cause it rarely can.

It's meant for two things. To keep the earth's soil at a near zero potential from one building to another. And to dispell fault currents.
 
wawireguy said:
I just realized that I really don't understand what the GEC does.
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What it does is takes the onus off of the power company and puts it upon the property owner to keep the earth at a near 0 potential.

Aside from that it connects the grounding electrode system to the service.
 
physis said:
This simply isn't true.
Just take a meter out there and see for yourself.
Grounding and bonding basically protects the buildings wiring system, you know, a way to trip the breaker.
As far as acting as lighting protection, good luck, cause it rarely can.
It's meant for two things. To keep the earth's soil at a near zero potential from one building to another. And to dispell fault currents.
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Did you read the information at the site I listed? What does "to keep the earth's soil at zero potential" mean to you? What does taking the meter out have to do with anything? You still have the GEC connection. Grounding and bonding also protects you when the fault occurs. Never said it protected against lightning. It doesn't. It would help if you understood the single point grounding concept. Read the article I posted.
 
bob said:
Did you read the information at the site I listed?
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No.

bob said:
What does "to keep the earth's soil at zero potential" mean to you?
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If you beleive that this can be done then perhaps you would like to demonstrate. At least without a big ol lightning grid.

bob said:
What does taking the meter out have to do with anything?
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Demonstrating this idea of zero potential earth.

bob said:
You still have the GEC connection.
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As you should.

bob said:
Grounding and bonding also protects you when the fault occurs.
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Could you put a percentage on property versus human protection? How bout the fact that extra "grounded" things are the other conductor needed to complete the circuit for serious shock hazards?

bob said:
Never said it protected against lightning. It doesn't.
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It's true you didn't mention lightning and I did in fact see that before I pushed the "submit reply" button. I shouldn't have assosiated that with you, I apologize for that.

bob said:
It would help if you understood the single point grounding concept.
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Maybe you could explain it to me. I'll give you a hint, it's something in this post that you disagree with.

bob said:
Read the article I posted.
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No, It's totally not my first bar-b-que.
 
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Dennis Alwon said:
That's because the GEC to the rod does very little. It's suppose to help for lightning strikes. It doesn't do very well at that either.
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Careful thinking like that:smile:......
Dennis Alwon said:
It's supposed to be for lightning strikes
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..huh?...Does that mean lightining won't hit it ...or lightning will hit it? How does it help for a direct lightning strike?If my system has the ultimate grounding system is my property better off? (I know you did'nt say direct, just let me run with this:smile:)

If lightning directly strikes your house, your electrical equipment, your building,ect,.......thats it! If the structure doesn't catch on fire, at the very least your equipment is toast.
 
raider1 said:
Here is what the NEC has to say about the funtion of grounding of systems.

"(1) Electrical System Grounding. Electrical systems that are grounded shall be connected to earth in a manner that will limit the voltage imposed by lightning, line surges, or unintentional contact with higher-voltage lines and that will stabilize the voltage to earth during normal operation."

Chris
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....limit the voltage imposed by lightning, line surges, or unintentional contact with higher voltage lines......OKAY, I'll buy that, but..
NEC said:
...stabilize the voltage to earth during normal operation
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This ones always bugged me:mad: How does it "STABILIZE" anything during normal operation:-??
The only point it may stabilize anything is at the point where the GEC and the GE meet. The earths contact resistance has a high amount of resistance, thus creating a voltage gradient around the electrode (lets say a rod). The point at which the GEC and the GE meet there is no difference of potential, but where the GE and the earth make contact there is an immediate voltage drop.:-?
 
kbsparky said:
Ummm ... nope, guess again. And then read section 250.66(A):



You can use a #8 wire on a smaller service if you want to. However, there are other rules about physical protection if you do.
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That's what I was thinking about.

But all the same, there is no prohibition in running a larger than #6 GEC to a rod. So I guess one can't technically say #6 is a min or a max. :grin: but rather just the nominal size.
 
ibew441dc said:
....How does it "STABILIZE" anything during normal operation:-??
The only point it may stabilize anything is at the point where the GEC and the GE meet. The earths contact resistance has a high amount of resistance, thus creating a voltage gradient around the electrode (lets say a rod). The point at which the GEC and the GE meet there is no difference of potential, but where the GE and the earth make contact there is an immediate voltage drop.:-?
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You have to remember first, an NEC GES is the second point at which the service is earth grounded (for grounded, service-supplied systems), the first being at the secondary windings of the service transformer. Second, there is a low impedance path between the first earth grounding and the second earth grounding. So nominally, the only voltage at the main bonding jumper is by way of voltage drop across the grounded service conductor. In the ideal scenario there would be no voltage drop, and 0 volts means 0 current, wherein high resistance to/through earth is moot.
 
ibew441dc said:
This ones always bugged me:mad: How does it "STABILIZE" anything during normal operation:-??
The only point it may stabilize anything is at the point where the GEC and the GE meet. The earths contact resistance has a high amount of resistance, thus creating a voltage gradient around the electrode (lets say a rod). The point at which the GEC and the GE meet there is no difference of potential, but where the GE and the earth make contact there is an immediate voltage drop.:-?
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I have always had an issue with that as well, I think it is more wishfull thinking then fact.
 
Smart $ said:
You have to remember first, an NEC GES is the second point at which the service is earth grounded (for grounded, service-supplied systems), the first being at the secondary windings of the service transformer.
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It does not matter how many times it connects to the earth, if you have enough current feeding into the grounding electrode it will not remain at the same potentional as the earth a few feet away from it.


Second, there is a low impedance path between the first earth grounding and the second earth grounding. So nominally, the only voltage at the main bonding jumper is by way of voltage drop across the grounded service conductor. In the ideal scenario there would be no voltage drop, and 0 volts means 0 current, wherein high resistance to/through earth is moot.
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I have no idea what your trying to get across here:confused:
 
Smart $ said:
You have to remember first, an NEC GES is the second point at which the service is earth grounded (for grounded, service-supplied systems), the first being at the secondary windings of the service transformer. Second, there is a low impedance path between the first earth grounding and the second earth grounding. So nominally, the only voltage at the main bonding jumper is by way of voltage drop across the grounded service conductor. In the ideal scenario there would be no voltage drop, and 0 volts means 0 current, wherein high resistance to/through earth is moot.
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The whole idea of earth grounding, although the NEC or almost any other document wont come out and say it, is to keep voltages between the planet and the stuff we put on it from getting high enough to be a hazard.

Without earth grounding you wouldn't have to go very far from one point to another, sometimes, to find at least minimally dangerous voltages.

Edit: the idea is to try to keep the earth at relative zero in relation to all the other voltages that are pretty much everywhere. That way we can deal with those other voltages specifically. And it does work rather well.

ibew441dc said:
How does it "STABILIZE" anything during normal operation:-??
Click to expand...

What I've said here is how. I'm not condoning the language, far from it.
 
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