Secondary H2O replaced about 2 years ago. Small tank leak developed last week. (Both primary and secondary H2O’s scheduled to be replaced on 07/12/05). In checking out all parts of the system in anticipation of change out, I discovered the following: With thermostat satisfied, “A” hot at H2O reads 2A, “B” hot reads 1A, and bare ground reads 1A. Copper water line reads 0. At panel, same readings. Feed is 10/2 w/g. No power connection to primary H2O, it is used as a preheat from geothermal system. Both H2O’s are 52 gal. A.O. Smith. It seems that this phenomena is unique to A.O. Smith heaters. Could their internal control wiring be utilizing 120V? There is no provision for connecting a neutral. In my opinion having a load on the bare ground is not a desirable, or safe, installation.