Developing a grounding system test plan

Status
Not open for further replies.

Strathead

Senior Member
Right up front, I am requesting that we don't get in to a discussion about ground systems or the technical aspects in this thread please.

The situation: I have a customer who requested that we test their grounding system. When I asked "How?" they sent me a test report from the electrical contractor in another State from another site. I don't know much about grounding, but I do know that doing a 3 point fall of potential test on a 2/0 wire cadwelded to the building and a buried ground ring tells you nothing.

My question: Since I don't believe the average Electrical Engineer know any more about ground rings and ground testing than a good electrician, does anyone know of a reputable contact who can develop a proper yearly testing plan for a site ground system?

One other option I see here is, for one of you who is expert to tell me I am barking up the wrong tree and a physical/visual inspection and a single fall of potential test point at the service is adequate.
 

jim dungar

Moderator
Staff member
Location
Wisconsin
Occupation
Retired Electrical Engineer - Power Systems
Connections (resistance) to dirt and interconnections between building steel and equipment enclosures are two different things. However, neither of them require yearly testing for the majority of facilities in the US. Of course, lightning protection components are a different matter.
 

zog

Senior Member
Location
Charlotte, NC
Right up front, I am requesting that we don't get in to a discussion about ground systems or the technical aspects in this thread please.

The situation: I have a customer who requested that we test their grounding system. When I asked "How?" they sent me a test report from the electrical contractor in another State from another site. I don't know much about grounding, but I do know that doing a 3 point fall of potential test on a 2/0 wire cadwelded to the building and a buried ground ring tells you nothing.

My question: Since I don't believe the average Electrical Engineer know any more about ground rings and ground testing than a good electrician, does anyone know of a reputable contact who can develop a proper yearly testing plan for a site ground system?

One other option I see here is, for one of you who is expert to tell me I am barking up the wrong tree and a physical/visual inspection and a single fall of potential test point at the service is adequate.
Why not just follow ANSI/NETA or IEEE Std 81 standards?
 

Strathead

Senior Member
Two. You have not read them? Maybe you should sub this out.
Subbing out is what I thought I implied. I am looking for an expert to develop a point by point inspection guide that can then be followed by any competent Electrician. I may not know, but at least I know that I don't know! Isn't that half the battle? I think that is going to be my new motto.
 

jim dungar

Moderator
Staff member
Location
Wisconsin
Occupation
Retired Electrical Engineer - Power Systems
What are you trying to accomplish?
Determine that your facility is connected to earth/dirt with a specific impedance
Check if an existing ground grid is still interconnected.
Or are you interested in the bonding between the conductive surfaces inside of your building.

What are your utilization voltages?
Is this a single building or a campus installation?
Do you have any 'open-air' switchyards?
 

Strathead

Senior Member
What are you trying to accomplish?
Determine that your facility is connected to earth/dirt with a specific impedance
Check if an existing ground grid is still interconnected.
Or are you interested in the bonding between the conductive surfaces inside of your building.

What are your utilization voltages?
Is this a single building or a campus installation?
Do you have any 'open-air' switchyards?
I can't answer, what they are trying to accomplish. That is kind of where I start. My impressions are this, but I could be wrong...
The Company is a fair sized Company. Often these companies get a "good" idea in their head and they dictate down without any idea what they really want or need. Here is the actual case.

The site has an incoming service rated 1200A at 208/120 3 phase. Free standing, feeds 1 building, which susequently feeds 2 more buidlings and some freestanding equipment sites. About 1/2 the site was installed by us, with a 2/0 ground ring woven around the new building and all of the equipment pads. The only reason anyone I have talked to can give about the ground ring is that that is what we have elsewhere. A year after installation they want it to be tested yearly, so I ask what tests they want to perform. I got vague answers and then I got a test report done by an electrican at the other site. They did fall of potiential test on ground points that are cad welded and can't be disconnected and just provided this data to them. This was good enough for them, because they asked an "expert" for a test and they got a test report. This is not good enough for me, since I am the "expert" they are asking for this site. After talking it out with one of their Engineers who's background is Chemical with a good grasp of electrical. He agrees and hopes to develop a proper test plan.

So, what needs to be accomplished is that which can be tested and inspected reasonably. The small amount of research I have done shows that I should be able to do 4 point potential tests that utilize CT's to cancel back feed in some locations for example. clamp ground test only on the service bond, etc. but I don't know th efirst thing about what testing is good, bad, useless, too extensive for the benefits etc. That is why I havef appealled to MH to see if I can get the Company to commision someone who does know to develop a written procedure that can be followed consistantly and offers good bang for the buck. Does this make sense?
 

brian john

Senior Member
Location
Leesburg, VA
So, what needs to be accomplished is that which can be tested and inspected reasonably. The small amount of research I have done shows that I should be able to do 4 point potential tests that utilize CT's to cancel back feed in some locations for example. clamp ground test only on the service bond, etc. but I don't know th efirst thing about what testing is good, bad, useless, too extensive for the benefits etc. That is why I havef appealled to MH to see if I can get the Company to commision someone who does know to develop a written procedure that can be followed consistantly and offers good bang for the buck. Does this make sense?
No to the four point test. This is utilized to determine soil condition prior to designing a grounding system.

Not soliciting work, but I am in Florida all next week, booked solid.
 
Status
Not open for further replies.
Top