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To begin with, a 6 ft ground rod will do absolutely nothing for high frequency discharges; the impedance of a single rod and the wire connecting to it is way to high to have any effect above a few 1000 Hz. If you're concerned about noise coupling into the computers, there are two ways to go about it. The first, which is probably easiest in your situation, is to make sure all the metal panels are electrically bonded to each other, to the building structure, and to the incoming power ground to create a low impedance return path for any noise currents. This approach is typically referred to as an "equipotential plane". The second approach is to ensure that there are no electrical paths between the noise source and the computers except at a single ground point connected to the building safety ground; the so-called "single point grounding system". Single point grounds have pretty much fallen out of vogue these days because unless you use fiber optic interconnects or transformer isolated data busses, you end up with a bunch of ground loops. Make sure you have good power line filters on the computers. The "EMI" filters in most commercial computer power supplies are junk. Buy a good quality line filter (not one of these things you get from Walmart) and make sure its well bonded to the building steel. Make sure any ground rod you add is bonded to the bulding safety ground with a conductor capable of carrying fault currents from whatever equipment you're connecting to the rod. This is a national electrical code requirement to avoid creating a hazardous fault condition by having two ground connections at different potentials. I've spent most of my career dealing with these kinds of interference issues in communications facilities, spacecraft, and aircraft. Most people tend to think of EMI control as a black art, but in reality its just a somewhat unique application of physics. Good luck, Keith
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