Why wouldn't the EGC for the item that might energize it be sufficient? If also isolated from that item (dielectric union perhaps) then why would it be likely to become energized?
I think you can still bring it to the first five feet of entry area if that first five feet is associated with a water pipe grounding electrode.
I'm going to respond to this without looking up and referencing code. I'm relying on my memory which may not be as good as it used to be. Once PEX is installed in a residential application, you no longer have a plumbing system capable of conducting electrical current. Sure, some will argue about the mineral content of water creating a conductor but generally, water itself does not conduct electricity. I have since retired but I was under the impression that a few code cycles ago, bonding of the incoming water line was no longer acceptable. As municipalities replace old water pipes, they are doing so with non-metallic piping. That metallic grid that used to exist is no longer reliable. The incoming water electrode was previously required as an acceptable GEC but that was assuming that the incoming water electrode was 10 feet in length. As an electrician and/or an inspector, there is no way to determine if the incoming water electrode is 10 feet in length so using it as a GEC is no longer acceptable. Sorry, I didn't have the time to quote specific code references.
Though that may be true, NEC wording hasn't really changed much in determining what is or is not an electrode. It doesn't state how to determine if something unknown is or is not qualifying though, that leaves us with installer and AHJ discretion on how to deal with an existing unknown buried water pipe. In most cases I have seen if they are replacing a metal pipe up to the building they usually bring it all the way inside. They are just asking for potential troubles later on if they make a conversion just outside when they could have brought it a couple more feet into the building while having the yard all dug up already.
I worked for a mid-sized city in Western NY state. The city was the AHJ and therefore I was such. I believe that the question of utilizing the incoming water electrode being used as a GEC came about with the 2014 code cycle. In the city I worked within, there was a program that replaced all the metal water pipe in the streets up to the premises property line where the shut off valve was located. That often left it up to interpretation whether the electrode remained intact for 10 feet as many city lots did not have 10 feet of land between their foundation and the city's property line. At that time, most outside inspection agencies and the city agreed that we would no longer accept the incoming water line as the primary GEC. Double ground rods spaced 6-feet apart became the norm on a service change in old construction. In new construction, bonding of the footer was required which became the primary GEC with a ground rod driven as supplemental. If memory serves me correctly, I believe it is 250.52(A)(1) that defines whether a metal underground water pipe is to be used as a grounding electrode. The last code cycle I enforced was 2017. It should be the same for 2020 but I do not have access to that edition. And of course, for all the technicality people out there, the AHJ enforces the International Code. You can get to the NEC from there but technically, you can't quote the NEC in enforcement. You have to quote the IRC for residential of the current code cycle. I believe that the IBC refers you directly to the NEC if I recall. Things may have changed since I retired.
I don't know about other codes you mentioned, but NEC has been 10 feet or more of metallic water piping in direct contact with earth must be utilized as a grounding electrode for a very long time. Has never been mentioned in the NEC how to determine if there is 10 feet or more in an existing install where you might not know for certain though - that would essentially be up to AHJ how to handle those situations.
To add to this before, I believe 1996 NEC, you could tag metal water pipe with GEC anywhere you wanted, and just put a bonding jumper around the water meter. It was then that they changed it to require connecting within the first five feet of entry, though still needed to bond around water meters if they are in that path.
I don't disagree with your statement. It would be up to the AHJ to make that decision just as we had to but we also coordinated our decision with the 3rd party agencies that inspect outside of the city so that electrical inspections would be uniform throughout the area. It's difficult when one entity requires something different from another entity. You mentioned supplemental grounds with the water pipe electrode and CEE. Keep in mind that a supplemental electrode such as a ground rod, is only rated to clear up to a 100A fault. Hence the necessity for two electrodes in a GEC system. I doubt that by mid summer in many areas, a single ground rod would be able to clear that much of a fault but as people often point out, the code is the minimum, the worst you can possibly perform. With our aging and antiquated infrastructure and ever more sensitive electronic equipment, grounding and bonding is extremely important. It should be better taught and understood than it presently is. Most electricians that I encountered as an inspector knew how to ground and bond to the code requirements but often, many didn't fully comprehend why.
I previously mentioned the legal path we had to take to dispute a non-code-compliant encounter. We couldn't just quote the NEC unless you were inspecting an other than one or two-family dwelling covered by the Residential Code. Most, if not all states adopted the International codes a few years back. An electrical inspector technically inspects to the requirements of the International Codes. As I mentioned, the International Building Code directs you to the NEC but the International Residential Code contains the enforceable electrical code in chapters 34 through 43. All Professional Trades Inspectors are required to enforce the requirements of the International Code Series. We did rely on the NEC most of the time but if it came down to a legal dispute, you had to start with the origin that permitted you to inspect and then work your way to the electrical code.
Yes how can it? if you put in a single rod that does have less than 25 ohms it will still limit current to a fairly low level.
