Remember that it's the electrician's job to ensure that all metallic piping is bonded to the electrical service and to the building's steel structural members. This does NOT mean steel studs. Regardless, the electrician may do a perfectly fine job during the building's construction, but over time, plumbers come in and replace parts of the metallic piping systems with plastic. They don't have a clue as to the risk they are causing in doing this. They also aren't going to place a bonding jumper around the replaced piping; they just walk away with a check in hand once the water is running.

This is why you really can't trust any grounding point except the one that's used for the building's electrical service. Even that can be compromised due to hack repairs, but at least there's a good chance that the power company's ground at the pole or transformer will be good enough.

Perhaps the most popular misconception that can be made is that if you provide your own ground rod for the phone system, you'll have a good ground. Nothing could be farther from the truth. Doing so will actually invite problems AND is illegal under the NEC.

Ed Vaughn, MBSWWYPBX