The purpose of this thread is to clear up some of the confusion I see Ham operators go through with respect to proper equipment grounding techniques. It is also to get into some of the Do’ Don’ts and Why. Grounding is a terrible word and one of the most misunderstood subjects there is in the electrical and electronic disciplines. The word GROUND itself is misinterpreted as most think it has something to do with earth or dirt when in fact it may or may not. So after 33 years as an EE with Telephone, electrical, and broadcast communications I wanted to take the opportunity to discuss the subject and maybe help some folks out With respect to Amateur Radio operations’ ground falls into three major systems of; Safety, RF, and Lightning Protection. All three are different systems but common. DO NOT FALL into thinking they are 3 separate isolated systems, because they are NOT. If electrically isolated from each other is a guarantee of problems, some of which can cause fatalities and serious property/equipment damage. So this is where I will start. As stated I see many folks who think they have to keep the Safety, Lightning, and RF Ground isolated and separated from each other. They have come to the impression that keeping them separate from each other will somehow make the system immune from noise, when in fact is creates electrical noise and some very serious safety problems. From a safety and operating perspective the huge risk is what is called Gradient Step Potential differences. Step potential differences are caused by stray currents running through the earth. The earth is a very poor conductor of electricity with high resistance and current flowing through resistance produces voltage differences. The two major sources of this current are our public electric utility grid, and lightning. In addition wiring mistakes by man contribute to the currents. Utilities use the earth as a conductor because it is much less expensive than wire. They use what is called a Multi-Grounded Neutral. At every forth pole or so (1/4 mile) they bond the small neutral conductor to a pole or tower ground. This causes normal load currents to flow in the earth. Utilities are the only ones allowed to use earth as a conductor. NEC forbids earth to be used as normal current carrying conductor. The reason why is the utilities operate run at very high voltages, and consumption is at very low voltages of 600 volts are less. Lighting does cause very large amounts of current to flow in the earth with cloud to ground strikes. This is where the term Step Potential is derived from. You have certainly heard over the years about lightning striking a tree, and people in the vicinity that were not directly struck were either killed or injured. What is happening when a tree or object is struck, the current flows outward away from the point of where it enters the ground along the surface. The distance between your feet is enough resistance coupled with the very high current flowing to develop enough potential voltage difference to kill and injure. The voltages can reach the 10’s of thousands of volts. The same Step Potential occurrence happens in electrical substations when the high voltage lines fault to ground. Extremely high current flow and workers in the yard are killed. In all electrical substations there is what is called a MESH GROUND Mat just underneath the crushed gravel. It is bonded to all the steel framework and ground rods spaced evenly around the yard to minimize the Step Potential differences. Yes Ground Loops are a very GOOD THING as it forms very low impedances between any two points OK hopefully it is now apparent why you should not have your grounding systems isolated, and why the Electrical Code requires all the various grounding systems to be bonded together. It is to have a planned path to limit the voltage difference. Otherwise all the systems come together inside you shack. When the difference becomes high enough it will find a path to equalize. It will equalize either through you or the equipment. Even under normal operating conditions the potential differences are noise. Any unwanted signal or voltage is considered a noise, and can interfere with radio operation. The trick is where to make the bonds. Well that is simple follow the Electrical Code as it is written. All ground electrodes must be bonded together to form a single ground electrode system. This is done outside by digging trenches, running the bonding jumper underground to bond the various systems together. Later we can discuss techniques and topologies to use inside the shack.