Concrete and Electrodes

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Dennis Alwon

Dennis Alwon

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Looking for comments on this-- taken from here E&S Grounding Solutions-- has a lot of code info. The article I am quoting can be downloaded but you have to sign up... http://www.esgroundingsolutions.com/downloads/electrical-grounding-tips-article/

I read this the other day and it made me think of the episodes that I have heard about with ufer's blowing out the concrete

Concrete
Many of the ground enhancement products contain concrete (often mixed with coke breeze), which is
typically installed around a copper conductor or ground rod. The primary purpose of this is to increase the
surface area and contact between the copper and the earth. The chief issue with concrete is that it has a
very poor current (amperage) handling ability. The water that is naturally found in concrete will quickly turn
into steam under fault conditions, cracking the concrete and thus making the electrode virtually useless. As
the electrode will be buried, you may never know that the electrode has been compromised.
Click to expand...

However I have not heard of this before

Using a Water Pipe as
a Grounding Electrode
Everyone does it, but does a water pipe provide effective grounding? Unfortunately, the answer is almost
always a qualifi ed “No”. It is important to understand the difference between the terms bonded and
electrode when speaking about electrical grounding. A ”bonded” object is when an electrician makes an
intentional metallic connection to ensure that there is no difference in potential, but is NOT intending that
object to be used as a path to earth for electrical faults. An “electrode” IS an object that is intentionally
connected and designed to conduct electrical faults to earth (and typically buried).
Water pipes provide a poor path to earth for electricity as the utility company typically coats the pipes
with tar to prevent corrosion, installs electrically isolative barriers, or uses non-metallic pipes. This is why
the National Electric Code requires that an additional grounding electrode be installed along with the
connection to water pipe. It is better to think of water pipe as a required metal object that must be bonded
to the ground system, rather than thinking of it as an electrode for the ground system.
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They use the terms " fault conditions" and "path to earth for electrical faults" sounds to me like they're confused. What does either of those conditions have to do with grounding electrodes?
 
infinity said:
They use the terms " fault conditions" and "path to earth for electrical faults" sounds to me like they're confused. What does either of those conditions have to do with grounding electrodes?
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Think in terms of lightning instead of faults. You are correct- faults are not going to blow out the concrete
 
When you make a statement like this it sounds like someone is describing the job of the EGC.

Using a Water Pipe as a Grounding Electrode
Everyone does it, but does a water pipe provide effective grounding
Click to expand...
 
How long for the concrete to become damp again or are they worried that the entire length of the rebar throughout the footings is now separated from the concrete and earth? Is that better or worse than rods taking a hit and becoming glassed over? I’ve heard of it but have never seen it. Nor have I looked.
 
Utility and copper pipe

Utility and copper pipe

The water company replaced all of the main water lines in my neighborhood. I watched them install a very large copper waterline under the street. It looked like a great electrode to me.
 
Yeah, I have never seen a water line with a coating on it. Usually if the line is replaced around here it is plastic. It is the plumbers job from the meter which is by the street,to the house
 
Dennis Alwon said:
Think in terms of lightning instead of faults. You are correct- faults are not going to blow out the concrete
Click to expand...

I read it again and don't see much in there about lightning. Does this company sell products designed to enhance the quality of electrodes?
 
infinity said:
I read it again and don't see much in there about lightning. Does this company sell products designed to enhance the quality of electrodes?
Click to expand...

No, I added the lightning since the ground fault was absurd. My point was that a lightning strike could do potential damage to the grounding electrode conductor.

Here is what they do
[FONT=&quot]Some of our electrical grounding services include:[/FONT]

  • Field measurements
  • Grounding Design
  • Grounding electrode design and analysis
  • Lightning strike analysis
  • Cell site grounding
  • Electrical grounding safety audits
  • Ground potential rise studies
  • Wenner 4 point soil resistivity testing
  • Power quality monitoring
  • Load analysis
Click to expand...
 
Dennis Alwon said:
Yeah, I have never seen a water line with a coating on it. Usually if the line is replaced around here it is plastic. It is the plumbers job from the meter which is by the street,to the house
Click to expand...

I have, however, seen coated gas pipe fairly often.
Some soil conditions/locations may justify coated water pipe. But more likely would be cathodic protection (DC voltage offset) which would generally require a dielectric union between the utility pipe and the building piping.
 
If the water line were coated with something, I don't think it would meet the condition of "in direct contact with earth" in 250.52(A)(1) and would not be a grounding electrode.
 
How often does the GE other then at communications towers and similar structures take on all the energy of a lightining strike? First it has to be a direct hit before it will even happen. If it is a direct hit the GE is probably one of the last things that gets much attention when it comes to damage observation.

Add: there is probably a reason there needs to be minimum 2 inches concrete encasement for CEE's as well. Often you are finding at least 6-8 inches of encasement in a footing.
 
packersparky said:
If the water line were coated with something, I don't think it would meet the condition of "in direct contact with earth" in 250.52(A)(1) and would not be a grounding electrode.
Click to expand...

Correct---- but if it were coated outside but not inside you wouldn't know it. I think that was a point they were making. I have never seen water lines that were coated. I am surprised they still use copper.
 
electrofelon said:
I get real skeptical with these types of companies. Seems they always way over emphasize the importance of grounding.
Click to expand...

And Harmonics, the root cause of all PQ issues grounding and/or harmonics. To solve the problems all you need are dollars, more ground rods, copper and a speciality transformer.
 
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