Electrical – Dangers of a Grounding Conductor

I second Kris's answer and also: (1) Grounding actively provides protection from electrocution in the case of large appliances, motors and other items with metal enclosures that must ensure exposed metal does not become energized due to a fault; and (2) Grounding is required with many electronics to achieve acceptably low radio noise emissions. A metal box does not shield surroundings from emissions generated within the box unless the box is well grounded (ever notice that the installation directions for microwave ovens and some computers require a ground be added by an electrician if one is not available).

Grounding loops can occur whenever two different grounds are electrically connected. They describe the phenomenon where electrical current unexpectedly flows between the two. For example, two separate grounds might have an electrical potential that differs by 0.2 volts. If a wire connecting them has a resistance of 0.01 ohms, then a 20 AMP current will flow between those two grounds. There is very little power in the flow due to the very small voltage difference, but the high current can cause unexpected corrosion and also problems with electronics. Current that flows through a ground loop originates from local effects and not from power measured by an electric meter. It is not included in an electric bill.

If there were no system ground for your home, you would have a greater risk of electrocution in certain situations and you could experience mysterious problems like this fellow who’s GFCIs keep tripping:

GFI trips everyday

The grounding electrode is only required to be 8' and buried 2-1/2' deep for a pipe or rod. The conductor is required to be continuous as you note but you stopped reading prior to the 4 exceptions 250.64.C.1 through 4. But the pipe is the electrode. With many home owners having to replace old galvinised pipe a problem has started when the old pipe is removed and replaced with plastic. I have had to drive new rods where ther was no longer 8' of pipe in the ground. This can cause problems especially if there are no other grounds (driven or Ufer) the most common. If you are concerned about the quality of your ground it is fairly easy to drive a new rod close to your panel and run a #6 copper conductor to the service. Many older homes the water main was the only ground. Adding a driven rod or pipe can only help if located close to the service.