In normal household electrical applications, most everything will have a common ground
point - that is to say, your electrical outlet
s will be wired to one or two ground points. These typically consist of an eight foot long copper
clad rod of otherwise conductive metal that has been driven into the ground and has a wire somehow attached to it.
An isolated ground, then, is...well, it does exactly what it says on the tin. It's a ground point for a single application (e.g., a single electrical outlet) as described above, but it tends to be used for other purposes revolving either around safety or noise reduction:
* In a home amateur radio or citizens' band radio setup, a base station's antenna (or something similarly stationary) will be grounded to its own ground rod to keep the radio from interfering with the other household appliances and vice versa
* In a commercial or industrial setting, your high powered equipment will be placed on their own (sometimes multiple) ground points, and your computers might be placed on their own (but odds are they're on the common ground)
* If your house is very old and therefore isn't grounded (and you likewise have a MacGyver bug about you), you might have placed an isolated ground or three around the home for your computer(s) or other appliances.
I have done this last one myself.
Before I go on and explain how to do this, I will warn you that this may not be a good idea. In fact, it is remotely possible it is in violation of a building code. If you are not sure AT ALL that this is a good thing, hire an electrician. Remember, electricity is an equal opportunity bigot - it hates everybody the same.
Now then, this is what you need to do:
0) Determine where you want the ground to be. It should be in close proximity to the application - either a grounded electrical outlet, or a transmitter antenna. Mark this with white marking spraypaint. (This is specific - it washes away after a fashion and is widely used for marking for work. It's semi-permanent, but if you're doing this on the lawn or bare earth it's trivial.)
1) Call Digalert or your local equivalent. They will give you instructions which you need to follow, and ask you questions on what to do. Have that white paint ready for this. Within a week, the area around your ground point (and probably your house as well) will have various and sundry multi-colored lines of paint indicating any underground utilities that run around where you are going, making your lawn resemble a high school gymnasium floor. AVOID THESE AT ALL COSTS! If the intended ground point will interfere with a utility, you absolutely must move it to another location. The wider the berth, the better here.
2) Have your equipment ready. You need one copper clad grounding rod, a bracket (ask the guy at the hardware store which one you use for the ground rod), a sledgehammer (or two - one short and about 10 lbs, one long and heavier if you feel it necessary) or a fence post driver if you have one available, a length of green or green and yellow striped (that color is very important!) insulated copper wire (12 AWG or 14 AWG) to reach from point A to point B, and if you happen to be doing this on an electrical outlet, you need a current tester, a face plate and/or a wall outlet that is specifically designated for "isolated ground". These latter two items are both colored orange, and for some reason are more expensive. (At last check, the wall outlet alone costs around $10 at Home Depot.) At this point, too, and again if this is an outlet, you will want to find a way to put a hole in the wall where the ground wire should come out. How you do this is left as an exercise to the reader.
3) Take your ground rod and, using your hands and your body weight, drive it straight down into the ground using your body weight to get it started. Moisten the soil with water if necessary.
4) Using a sledgehammer (The short one if you have two), start tamping your rod down into the ground. Be patient - this can take a bit of time. Use the longer one when it becomes comfortable to do so to speed things along. Keep going until you have six inches (15 cm) of rod still remaining. Remember too that this is pretty permanent - once it's in, you need earth moving equipment to get it out.
5) Apply the bracket to the ground rod. Strip one end of your length of wire and insert that into the appropriate spot on the bracket.
You have now driven your very own ground rod.
For antenna applications, you need to locate the antenna's ground. This is where your grounding wire goes. Failure to do this will result in a potentially catastrophic standing wave ratio feeding back into your radio, and if the power is high enough, you will lose your finals.
If you are applying this to an electrical outlet, you will probably be part way on the repair on the outlet. Assuming all is safe, you can insert the other end of your length of wire into the hole you made in the building. Wire this to your ground on your outlet, and proceed as per the instructions in the electrical outlet writeup.