Originally Posted by
Brian Robertson
I've gotten gotten readings at the grounding conductor at the water meter, of close to an amp.
Originally Posted by
Brian Robertson
By the way this conductor is coming from the service panel to the piping.
Question: Is that conductor "bonding" that water pipe to ground at the panel, or, is that conductor "grounding" the system to that water pipe?
By measuring 1 amp current flow, you are showing that there is a 1 amp ground-fault someplace, or a total of 1 amp of ground-faults in several places.
Depending on what that conductor does (see question above) could give an indication of where (and what) the cause it: service equipment and upstream, or, downstream of the service equipment.
If there is 1 amp on the conductor which is serving as the grounding electrode conductor, and that water pipe is the grounding electrode, then you may simply have a bad neutral connection forcing some current to go through the grounding electrode system back to the transformer (or as complicated as having a bad neutral, especially if underground, nicks in the insulation allow corrosion to start, which eats away at the neutral conductor).
Electrical current not only takes 'the path of least resistance', it 'takes all paths' available to it. If the 'path of least resistance' (the neutral) is a low impedance path as it should be, then you may not be able to measure the current flowing on the grounding electrode system and through earth, because its resistance is much much greater.
If there is 1 amp on the conductor that bonds the pipe to ground, then you have 1 amp flowing on that pipe ... from somewhere. Use your voltage sniffer to check for 'live' plumbing fixtures, you may find one, and somewhere around there may be a conductor being crushed against a pipe, causing electrical leakage to the pipe. Or maybe just a damaged wire with the insulation cracked, missing, etc.
I remember that I would occasionally find energized cast iron drain piping in crawlspaces under older homes, something, somewhere, was energizing it. Besides, isn't a cast iron drain system an "interior metal water piping system"? Thus, it requires bonding to ground.