installing a ground rod

[cadpoint]

Your floor apron could be up to 2' thick there and as wide there
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The height of the wall determines the apron's size and depth around the edges.

 

[LarryFine]

I drilled about 1 1/2 feet from the outer wall and about 1 1/2 deep.

Have you tried a drilling in an out-of-the-way area inside the building? Nobody says the rod has to be outside. Or, horizontally through a basement (if there is one) wall?