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ONE problem, cold water pipes don't pass code any more. Of course a really clear description of what is going on would help. better still a complete diagram with distances. And drop becomes part of the = requirements both under normal operating conditions and under motor starting conditions.
?-)
Comments are for the US.
Water pipes (min 10 ft metal in the earth) are required to be used as an earthing electrode, just as they have since time began.
Since they may be replaced by plastic, a "supplemental" electrode has been required since 1978. This is not a huge change - for at least 50 years the NEC has required a "supplemental" electrode if the water pipe was 'likely' to be replaced by plastic.
Water pipes are a good electrode (particularly if it is a metal municipal water system). Ground rods were commonly used as the supplemental electrode. They suck. For new construction a "concrete encased electrode" (often called a Ufer ground) is also usually required. It is also a good electrode.
For a short-to-ground to trip a circuit breaker there has to be a metal "ground" path back to the utility transformer (it uses the N-G bond at the service). Earth can not be used. It is equally stupid to use the earth as a "neutral" path.
Baer
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I am not seeing any point of serious disagreement here. The change in = the NEC was due to the prevalence of plastic in water distribution systems = and replacements. In new construction now the service entry point ground rod (electrode) is often just about the only (decent?) ground/earthing contact.
If someone is interested in having a really good ground system (and is willing to spend money) i can explain how to do it. There are at least 4 others in s.e.d who can as well.
?-)
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