Please advise what house wiring is required for electronic cooktop [flat top] ranges. Installation stipulates must have 3-wire, single phase A. C. 208Y/120Volt or 240/120 Volt, 60 hertz electrical system. Our house is 23 yrs old with 3-wire for range over 10 years old. Problems with four (4) cooktop replacement ranges, the surface elements work real nicely; however, the Oven and Oven light has been inoperable on all four new units out of the box from the factory with installation in our home. Certified electrician says in house wall wiring is correct, circuit breaker box is correct and as required--There is no reason that oven should not operate on current house wiring. He found no loose wires either. Sears Technicians stipulates house wiring ok for regular electric but the electronic cooktop range needs an operable ground wire for oven to operate. They found circuit breaker box and wiring to be correct as 110/240 but when cooktop range is plugged into the wall wiring it goes to 240 on one leg of wiring and zero on the other.?????? GE Tech stated house needs 3-wire, three-phase A. C. electrical system. However, their installation booklet states requires 3-wire, single-phase A. C. 208Y/120V or 240/120V, 60 hertz electrical system. We are confused. Help??? Please! Thanks for any insights or suggestions or corrections.