Todd, I think we're probably using different terminology. But yes, I'd be willing to agree the copper pipe is energized, in the sense that the assumed ground fault current is flowing through it.
In the eye of the NEC, there is a connection at the service entrance between the green grounding wire and the white neutral and ground. An appliance ground fault current SHOULD flow through the green grounding conductor to the service entrance, and from there, take the path of least resistance through that neutral wire back to the transformer on the pole. Of course the higher resistance path through the ground is in parallel with the neutral wire, so you get some current through the ground as well. It is normally not a good thing for there to be a lot of current through the ground, and its presence could indicate a problem with the neutral connection, etc.
Yes, the latter is what I assumed also.
My assertion was that if there was enough
Agreed. Except that there is no voltage to speak of on the ground wire while it is connected to the copper pipe (i.e., to ground). There is a current through the wire. When the connection to the pipe is broken, at that time a voltage is present between the pipe and the wire. Placing yourself across that voltage is what could be hazardous.
If that was the case, I wouldn't handle anything
Well, touching the plumbing fixtures should be safe because they are essentially at ground potential, again due to the copper pipe connection. That is a benefit of the grounding system. But if currents are detected in the grounding wire, something is amiss and maybe should be corrected.
Fascinating. I'd be lost in that area.
The reason for that jumper is more likely that the meter itself does not represent a good, low-resistance path. You see those jumpers around plastic-bodied filters also. In the past, service entrance grounds were often connected to metal plumbing systems. In many cases these systems were "upgraded" to plastic, and the residence was left without any ground connection at all!
FWIW, with so much PVC in use in new construction, the NEC now requires a dedicated ground rod or two at the service entrance.