grounding

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zog said:
What is the point of having the test witnessed?
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If we are talking strictly about NEC compliance there is no point to the test in the first place.

Here when we have to test for job specification requirements a representative from the engineering firm will be the witness.
 
stupid!

stupid!

much to my chagrin, our State office has ruled that it is the "inspectors duty to show that there is more than 25 ohms resistance before a second rod can be required". Thereore most of our installations have 1 rod.
 
augie47 said:
much to my chagrin, our State office has ruled that it is the "inspectors duty to show that there is more than 25 ohms resistance before a second rod can be required". Thereore most of our installations have 1 rod.
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There is an interesting situation, since there is lots of argument that a second rod won't make a difference if you have over 25 ohms. Does the building dept. supply the inspectors with a tester to check ground rods ?

To respond to Raiders question if I had done a test in front of the inspector. No, he would not except that. He wanted "third party testing" not my favorite type of party.
 
Just becarful, you may be a better ground path then the rod.
 
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xformer circuit

xformer circuit

According to the very informative link below,

http://www.newarkinone.thinkhost.com/brands/promos/Earth_Ground_Resistance.pdf

there may already be currents in the ground. I guess that's why they use different frequencies. So, you should first measure the open circuit voltage across the rods to check on how much noise is in the vicinity. If it's negligible, you might get a meaningful reading.

The link also gives soil resistivity tables so you can get a ballpark number on what to expect. There is a big variation, with swampland being the lowest resistance.

They also talk about ground rod maintenance. . .?
 
acrwc10 said:
To respond to Raiders question if I had done a test in front of the inspector. No, he would not except that. He wanted "third party testing" not my favorite type of party.
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It is unfortunate that there are inspectors such as this out there.

Chris
 
raider1 said:
It is unfortunate that there are inspectors such as this out there.

Chris
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e57 can back me up on this, it was in San Fransisco, they like to do that kind of thing.
 
acrwc10 said:
e57 can back me up on this, it was in San Fransisco, they like to do that kind of thing.
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I find it absolutely absurd that an inspector would require third party inspections to verify a ground rod had a resistance of 25 ohms.

Again I would say drive the second rod and be done with it.

By the way, in My area this is really a moot point due to the fact that all footings are required to have at least 2 #4 reinforcing bars installled continiously through the footings, so ground rods are not need very often.

Chris
 
raider1 said:
I find it absolutely absurd that an inspector would require third party inspections to verify a ground rod had a resistance of 25 ohms.

Chris
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And so do I.


Roger
 
And so do I, and I AM a 3rd party tester. For a ground grid at large industrial or power plant that has specific requirements than I understand that, but for a single rod, dont see the point.
 
acrwc10 said:
I have tried to argue the point with an inspector that we had well under 25 ohms with a single rod. His reply was " we need third party testing to verify ".
Oh brother ! And I have a good earth ground tester, not to mention the other simple and cheap methods of testing the rod. Second rod is cheap and no arguing.
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Exactly what path are we testing the resistance of? The path between the ground rod and the dirt? The ground rod and the gec? The ground rod and the lug inside the meter? The dirt and the grounded conductor from the street?

I tried searching the threads for some answers and this was the closest I could get.
 
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