Kbar wrote:hook the green neutral wire up to any fitting in the system to insure I have a good earth ground in the event of element failure
you can silver solder a tab to the body of the RIMS system that'd be the best way providing you the maximum contact area where the electrical energy will be appearing first. Use heavy multi strand wire because it has a higher carrying capacity and make it heavy so it can take the heat of a hot short.
You can also tin the wire with lead solder and use a band clamp to affix it to the body. The reason to tin it is simply to increase the contact area as the solder squishes. Abrade the body where you'll clamp it to get as clean a connection as possible.
Ground is a funny thing In a high voltage short you need a very robust ground and preferably more than one, because you want the electricity to have as many pathways to ground as you can provide and have them as robust as possible and well ahead of where you'll you in the circuit.
Pipe fittings may not provide a worthy grounding point. This because the electrical resistance between a fitting and the part into which it is screwed may be quite high because of the thread sealant used. Break out that Ohm meter.
Google around about Grounding Residential Dwellings and you'll find that it really is a complicated thing not to be undertaken lightly nor done by the uneducated.
Grounding to the screw part of the element may be unhelpful because of the resistance between it and the body of the RIMS tank and also because the element is insulated from the actual heating element part. So any power that finds that part of the element will have already traveled through something else and plenty of power will have traveled far and wide before enough can be siphoned off by that site.
This is what I would do (not because I'm so damn smart, but because I've seen it done in commercial applications):
Put a ground wire on every vessel and on any substantial metal component with which you stand a chance of touching.
Then, do not merge the ground wires. Run them independently and directly in as straight a path as possible to the building's main ground cable. If you can augment the building's ground with yet one more grounding spike this can only be good, but don't place closer to any other ground spike than say 6 or 10 feet.
Water all by itself is a shitty conductor of electricity. Add some salts and ionic or colloidal minerals and all that changes.
