I am looking for assistance in a very simlple application. I have a metal frame structure that requires an earth ground. I am required to verify the ground is adequate. It is a typical 1/2" rod driven into the ground. I am trying to verify that the ground is adequate from the surface down. I have a VOM, can this be done with this meter or is it necessary to have another type of meter? Please help.

 

Originally posted by tjc007@Apr 28 2006, 01:59 PM
I am looking for assistance in a very simlple application. I have a metal frame structure that requires an earth ground. I am required to verify the ground is adequate. It is a typical 1/2" rod driven into the ground. I am trying to verify that the ground is adequate from the surface down. I have a VOM, can this be done with this meter or is it necessary to have another type of meter? Please help.

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Check NEC code 250.52, "Grounding Electrodes" for acceptable methods of grounding equipment.

To answer you more directly, yes, if the rod is 1/2" diameter or greater, is made of copper or other listed material, and at least 8 feet in length, it is an adequate ground. Iron, steel or stainless steel rods must be at least 5/8" in diameter.

This is strait out of the code book and no meter is required to verify that it is acceptable. If you are in an area that has particularly rocky or porus earth to drive the grounding electrode into, then you may use two rods, bonded together, and driven in the gorund at least 8 feet apart from each other.

Hope this helps.

 

Depending on the application, the measured ground can be as low as 5 ohms.

Visit Biddle and download their Getting Down to earth application note for more information.