I'm a non-electrician (computer person) charged with replacing some old, cracked outlets that can no longer reliably make contact with a plug. The building is an old Catholic school built in 1945, but the wiring in the area I am working on was upgraded at some point, probably semi-competently; Catholic schools are prone to cut corners on building maintenance. I replaced four outlets (3-prong, romex wire, grounded to box/no ground wire, replaced with 3-prong GFCI) and all went smoothly until I climbed to the 2nd floor, went to the 2nd floor panel, turned off the circuit breaker for the room, and found to my surprise: Voltage from hot to neutral: 15V Voltage from hot to ground: 15V Voltage from neutral to ground: 0V Resistance from neutral to ground: ~300 ohm The same pattern occurs in several rooms on the same floor, but the hot->neutral voltage w/circuit breaker off varies from as little as 5V to as much as 35V in some rooms. A few rooms do show 0V. I searched the web extensively, but could not find any mention of a situation in which a circuit breaker is turned off yet current can still flow from the hot wire. Is there any chance that anyone might explain the possible cause(s), and whether it's something I can handle myself, or an electrician will be necessary? Thanks very much!