What is the GEC actually accomplishing on a day to day basis?

JoeNorm

Senior Member
Location
WA
Let's say we did an experiment and went into a modern neighborhood and cut the GEC in-between the house and the grounded/Ufer. What would be the issues that we might see pop up over time?

A connection to earth is holy in this field of work, but I am trying to understand what it's actually doing. I find it interesting that two ground rods in a rocky trench backfilled with dry rubble are treated the same as the same two driven into moist clay. Same goes for a Ufer in a house built on bedrock. It's like we're just going through the motions.

I am here to learn, so anything you have to add on this topic is appreciated.
 

Hv&Lv

Senior Member
Location
-
Occupation
Engineer/Technician
Nothing until a lightning strike nearby or a neutral wire gets ripped down in a storm.
Surges (faults) on the ground are directed to earth through the ground rod.
Ground rods are for faults. As long as you never have one you won’t need one.
I have worked on houses where the wire to the ground rod was cut off and had been that way for years. The copper price spike a few years back did exactly what you described.
Thieves removed the wires
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
For starters, it creates an equipotential plane.

All voltage is at the same potential.

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It really doesn't create an equipotential plane...if there is voltage on the conductor you connect to the grounded electrode, that voltage does not go away...it simply energizes a small amount of earth around the grounded electrode. Not even a large enough area around the electrode to eliminate a step potential.
 

masterinbama

Senior Member
It really doesn't create an equipotential plane...if there is voltage on the conductor you connect to the grounded electrode, that voltage does not go away...it simply energizes a small amount of earth around the grounded electrode. Not even a large enough area around the electrode to eliminate a step potential.
True.

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infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
Let's say we did an experiment and went into a modern neighborhood and cut the GEC in-between the house and the grounded/Ufer. What would be the issues that we might see pop up over time?

A connection to earth is holy in this field of work, but I am trying to understand what it's actually doing. I find it interesting that two ground rods in a rocky trench backfilled with dry rubble are treated the same as the same two driven into moist clay. Same goes for a Ufer in a house built on bedrock. It's like we're just going through the motions.

I am here to learn, so anything you have to add on this topic is appreciated.
It might help with a nearby lightning strike but IMO the more important part of the system is the main bonding jumper.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
Nothing until a lightning strike nearby or a neutral wire gets ripped down in a storm.
Other than a common metal underground water piping system, a grounding electrode provides very little protection for the building electrical system where the service neutral is open.
Surges (faults) on the ground are directed to earth through the ground rod.
Yes, it can help with that issue.
Ground rods are for faults. As long as you never have one you won’t need one.
While they may help to clear faults from accidental contact with a higher voltage, they do little to help clear faults on a system operating at less than 1000 volts.
I have worked on houses where the wire to the ground rod was cut off and had been that way for years. The copper price spike a few years back did exactly what you described.
Thieves removed the wires
Not uncommon.
 

suemarkp

Senior Member
Location
Kent, WA
Occupation
Engineer
Maybe help dissipate static electricity from your spinning disk drives in a computer, a tube type TV, or and outside antenna. However, you oculd skip the ground electrode at your house and rely on the ones in the utility distribution to dissipate static. One megohm to ground will be sufficient to bleed static.
 

retirede

Senior Member
Location
Illinois
We had to cut a grd electrode copper #4. As soon as I cut it. The lights to the house next door went off.
I’m guessing that went to a metal water pipe, not a rod in the dirt?

House next door was missing the noodle and the neutral current was flowing on the pipes and then through the GEC you cut to the neutral bond.
 

JoeNorm

Senior Member
Location
WA
I wonder why we are not required to prove that the electrode has an effective path? Or maybe in some places you are?

My question still stands about a house built on rock. Will the Ufer have any connection to ground in this case? Maybe soil backfilled around the foundation is enough? I ask because we actually see this a lot in my area. I have never tested a Ufer like this myself.
 

Hv&Lv

Senior Member
Location
-
Occupation
Engineer/Technician
I wonder why we are not required to prove that the electrode has an effective path? Or maybe in some places you are?

My question still stands about a house built on rock.
We aren’t required to prove anything as long as there are two rods.
I’ve been to a building that was built on rock.
The contractor used a rock drill to drill two 1” holes and they threw the rods in. They were six feet apart though and it passed...
 

hillbilly1

Senior Member
Location
Atlanta,Ga
Occupation
Field coordinator/ technical support
Nothing until a lightning strike nearby or a neutral wire gets ripped down in a storm.
Surges (faults) on the ground are directed to earth through the ground rod.
Ground rods are for faults. As long as you never have one you won’t need one.
I have worked on houses where the wire to the ground rod was cut off and had been that way for years. The copper price spike a few years back did exactly what you described.
Thieves removed the wires
Did power plant upgrades on some cell towers years ago, the grounds from the towers were cut off about as high as you could reach. The copperheads were going around collecting it. Looked like it had been gone quite a while. Customer said they quit replacing it because it would be gone again the next day! LOL!
 

Hv&Lv

Senior Member
Location
-
Occupation
Engineer/Technician
Did power plant upgrades on some cell towers years ago, the grounds from the towers were cut off about as high as you could reach. The copperheads were going around collecting it. Looked like it had been gone quite a while. Customer said they quit replacing it because it would be gone again the next day! LOL!
We started using copper coated steel wire in the stations and for pole grounds.
Spent some time educating the scrap dealers on the wire and getting them to use a magnet on all copper looking wire.
Caught several thieves this way. Some never try it when they attempt to cut 4/0 copper coated steel wire.
 

jaggedben

Senior Member
Location
Northern California
Occupation
Solar and Energy Storage Installer
Let's say we did an experiment and went into a modern neighborhood and cut the GEC in-between the house and the grounded/Ufer. What would be the issues that we might see pop up over time?

A connection to earth is holy in this field of work, but I am trying to understand what it's actually doing. I find it interesting that two ground rods in a rocky trench backfilled with dry rubble are treated the same as the same two driven into moist clay. Same goes for a Ufer in a house built on bedrock. It's like we're just going through the motions.

I am here to learn, so anything you have to add on this topic is appreciated.
If you cut the GEC at one house, most likely no one will ever notice a difference.* If you cut the GEC at all the houses in the neighborhood, people might notice an increased likelihood of damage to electronics due to lightning or high-voltage surges from utility problems.

*Since you said 'modern' neighborhood, we could take that to mean that there isn't a metal water pipe distribution system that connects all the houses' grounding to each other. Meaning that what happened to Buck in post #11 won't happen to you. But what he described is a good reason to check that your GEC isn't carrying a surprisingly high number of amps before you cut it. Especially in older neighborhoods.

I agree that there is a certain amount of going through the motions involved. But if everybody stopped grounding everywhere, that would probably be bad.

I wonder why we are not required to prove that the electrode has an effective path? Or maybe in some places you are?
Because that would be a much bigger pain-the-butt than it is worth. Basically, if the vast majority of the grounding out there does a little bit of something most of the time, then it's doing its job. It isn't so critical to test every component of it for perfection. Mike Holt has some videos out there where he tests the resistance of electrodes, in case you want to see what it involves.

My question still stands about a house built on rock. Will the Ufer have any connection to ground in this case? Maybe soil backfilled around the foundation is enough? I ask because we actually see this a lot in my area. I have never tested a Ufer like this myself.
The ground is the ground, i.e. the earth (NEC definition!) and rock is just as much a part of it as soil. So the NEC does not care. Depending on the composition of the rock it may or may not be all that much less conductive than soil, especially for the purposes of detecting high voltage utility faults.
 
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