NEC 250.53 (B) requires a minimum of 6-ft between electrodes

[roger]

I don't know if this is the information Tom was talking about but it's pretty informative.

https://www.aemc.com/userfiles/files/resources/applications/ground/APP-Ground-SoilResistivity.pdf

 

[Cjmccarthy]

I don't know if this is the information Tom was talking about but it's pretty informative.

https://www.aemc.com/userfiles/files/resources/applications/ground/APP-Ground-SoilResistivity.pdf

Thank you.

 

[CoolWill]

Not vodoo at all. Testing was done on ground rods to detetmime why 2, why 6 ft apart…I have info from AEMC I can post in a few dsys

Of course it's voodoo. If it wasn't, there would still be an ohm requirement when adding the second rod. Or third or fourth. The code basically says, "You have to get 25 ohms or less if you use one rod, but if you use two, don't worry about it."

Now, someone might have done some tests to verify that it all works, but it was still shipped out of thin air to begin with.

 

[LarryFine]

The code basically says, "You have to get 25 ohms or less if you use one rod, but if you use two, don't worry about it."

Probably based on recommendations from ground-rod manufacturers.