Open your book?
What kind of comment is that?
Let's look at the Code on cd with the commentary for a second.
""Section 250.53(D)(2) specifically requires that rod, pipe, or plate electrodes used to supplement metal water piping be installed in accordance with 250.56. This requirement clarifies that the supplemental electrode system must be installed as if it were the sole grounding electrode for the system. If 25 ohms or less of earth resistance cannot be achieved with one rod, pipe, or plate, another electrode (other than the metal piping that is being supplemented) must be provided. One of the permitted methods of bonding a supplemental grounding electrode conductor to the primary electrode system is to connect it to the service enclosure.
The requirement to supplement the metal water pipe is based on the practice of using a plastic pipe for replacement when the original metal water pipe fails. This type of replacement leaves the system without a grounding electrode unless a supplementary electrode is provided. """""
If we are required to supplement the water pipe with aditional electrodes,and these supplemental electrodes are required to be the sole grounding electrodes for the service, then the water pipe must not be too reliable of a source. This would mean the water pipe does not cut it as a grounding electrode.
Or am I still reading this wrong?
Dnk......
