Back in June I was involved in a project to ground a 400' communication tower being built. The specs said that there was to be a ground grid, consisting of #2 copper, which was to be placed in a 36" deep trench, in a cross-hatch method. At every 10-15' of conductor, we had to place a 10' X 3/4" rod. Now consider this. The top of the rod was to be 36" deep, also. No problem, Huh?
At 4', we ran into shale rock. Tried the hilti method (both straight and 45 degrees), which did not work. One of my fellow workers said that the line crew for our utility had a rod driver bit which fit on a jack hammer, driven by a large air compressor.
Worked good for the first 5 rods, then started to bog down. I was standing in the trench (36" deep. remember) while my fellow worker was standing on grade. He would hold the jack hammer and control the air, while pushing down. I would reach up to the jack hammer body, and pull down, letting my 240lbs assist in the driving of the rod. this work for about 5 more rods.
Then the unthinkable happened. The bit, which was nothing more than an old jack hammer bit, cut off about 12" in length, with a 3/4" hole driller into it, broke.
Since my fellow worker was running the controls, and bending over somewhat, he let go of the handles to catch his balance. I, on the other hand, was in the trench pulling down on this heavy piece of equipment, could do nothing but turn away from what I was sure was going to be head wacking event.
It fell, but instead of hitting me in my hardhat, it pulled my right arm behind my back, while I was turning away from it.
Needless to say, 90 days and 1 operation for a torn rotator cuff later, I still don't have 100 percent use of my right arm, tho I am doing alot better now. I can comb my hair with my right hand, shave, shake hands, etc...
My advice it to try the Hilti, but be carefull of over extending yourself with it. If you have to go with a jack hammer type of driver, I pity you, and ask you to be extra carefull using it. I thought I was, but in 1 second I found out I was wrong.
Rick Miell
