ok, lets throw this around(i'm sure it's been discussed already)

What are we doing now with our bonding jumper that we used to connect to water main,jump meter, and connect to house water piping,now that almost all of it is being installed in plastic/pex tubing.Keep in mind that most faucet and tub connections are still short lengths of copper tubing.

The inspectors and contractors I know do not consider these isolated sections of metal piping a piping system or is it likely to become energized Look at 250.104(B) '05 NEC

Definition of "Metalic water piping system" Needed in the NEC?

--piping system or is it likely to become energized ---

Perhaps not, Are there wires near by?

A very interesting situation. We "should" bond the duct work between flex and transitions.
Should we have to bond across all sprinkler victolic fittings? Those all have the rubber gasket ya' know',Not every length is secured by a clamp type hanger, most are just hangers.Those clamps don't have teeth either.

HVAC- I have had live flex!!!! Scary discovery!!!!

bonding ductwork, now thats never been an issue in all the homes ive wired, surprisng.....
I wonder if they consider it done by the equip ground conductor from the branch circuit, hmmmmmm

Here in Florida, metal framming members are required to be bonded to the electrical system.

It's been a while since I have seen metal duct in residential but they usually had a flex connector between the air handler and duct work (sound isolation) so the EGC would not be much help in bonding it.

When metal piping is the minority in the plumbing, it is not required to be bonded. This does not prevent it from not being bonded if there is a likelyhood of it becoming energized. Take the metal framing mentioned in Florida. The metal framing supports the electrical and plumbing systems. Since there is the likelyhood of becoming energized, i.e. lightening strikes, it stands to reason to ground and bond it. I am not too concern that they will become energized from the house distribution because if wired properly, the OCPD will open. I am more concern with other or "outside sources" that may not be grounded. This will create a potential since the electrical and metal plumbing is grounded to earth.

Odds are the there is not a reason to bond a "isolated" section of pipe. This does not prevent us though not to examine it for the possibility of bonding.

Tap water is not considered to be conductive. Pure water is non conductive. It is the impurities in the water that conducts the current.

Let's say that you are compelled to ground your isolated piece of pipe in your example and the rest of the plumbing to include the main water supply line is made of plastic, you would have to run a ground wire all the way back to the panel.

Likely is not defined in the NEC, therefore you need to look at a dictionary.

According to Merriam, likely means probably, not possibly.

Imagine buying a sweepstakes ticket, how much would you spend for one that is:
likely a winner,
probably a winner,
prossibly a winner,
or maybe a winner?

metal framing members(ie studs). are bonded here too, but i am talking about the sheel metal plenums on the hvac systems,usuaaly rectangle, and running along the length of the ceiling space in the basements.

Exactly Greg, I always(new and old,if found)Bond at a minimum the transition (sound isolator) simply with a #10 some stake ons and just self tapping screws, With the flex,I'll usualy just use the support wire in the flex and tek screw that to the duct.

Never been asked to, just makes me feel better.