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Grounding 2 point test result failed

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PowerdT

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San Diego
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Electrical Engineer
synchro said:
If you measure a significant current through a ground conductor with a clamp meter, then that may interfere with a resistance measurement made across the conductor. But if this happens, I suggest measuring the voltage across the conductor and then dividing it by the current measured by the clamp meter to get the resistance via Omm's law. Use the most sensitive setting on the meter. A true RMS clamp meter would be desireable because there could be harmonics present.
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Joethemechanic said:
There is always going to be a small current on the grounding conductor that runs between the NG bond and the ground rod. After that you really shouldn't have any.
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I tried to do line diagram. This are the test and results I received.

I have fluke 376. It should be good for true RMS value
 

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Joethemechanic

Joethemechanic

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Electro-Mechanical Technician. Industrial machinery
Well to start with rod 2 looks like an isolated ground. Busbar 3 looks to be bonded to the steel structure of the building. Steel building structures can or can not be a low impedance path to any other part of the structure. Other than that I'd start looking for loose or damaged connections on your grounding conductor
 
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PowerdT

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Electrical Engineer
Joethemechanic said:
Well to start with rod 2 looks like an isolated ground. Busbar 3 looks to be bonded to the steel structure of the building. Steel building structures can or can not be a low impedance path to any other part of the structure. Other than that I'd start looking for loose or damaged connections on your grounding conductor
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Yes rod 2 seems to be isolated ground, which is code violation. However i dnt know why rod 2 result 3 ohms. If specially rod 1 was 0.3 ohms

The server busbar I guess are I think used #6 EGC
 
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PowerdT

Senior Member
Location
San Diego
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Electrical Engineer
John Adams said:
The 2023 NEC clearly states that a telecomm grounding or bonding conductor never needs to be more than a #6AWG. Chapter 8 Communications
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Is #6 bonding conductor from busbar to telecom equipment. Would that be the same from the electrode to busbar?
 
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