An isolated phase bus disconnect switch has a cylindrical aluminum center conductor coaxially disposed within a cylindrical aluminum housing. The center conductor is composed of two fixed axially spaced sections and a coaxial telescoping sleeve assembly which moves axially to make and break electrical contact between the fixed sections. One end of each fixed section and both ends of the sleeve assembly have copper contact rings fixedly attached thereto. Adjoining surfaces of the copper-aluminum interfaces are silver plated, and each of the adjoining aluminum members is axially slotted to permit flexing to allow for differential thermal expansion, while at the same time preventing relative motion between the plated surfaces.