An electrochemical cell assembly in which one or more grounded conduits, that can be an oxygen product tube or simply inlets or outlets, are connected to the electrically driven oxygen separator. In order to prevent the conduit(s) from degrading due to electrochemical reduction due to the electrical potential produced between the electrically driven oxygen separator(s) and the grounded conduit or conduits, a conduit is formed in whole or in part by a ceramic material that is an electric insulator and that is also resistive to electrochemical reduction. The ceramic material comprises distinct phases of magnesia and spinel or magnesia, spinel and yttrium aluminate.