An insulated glass unit (500, 1000, 1215, 1305, 1400), comprising: first and second lites (505, 1010, 1410, 1415); an optically switchable device disposed on one of the lites; one or more electrical power distribution components in electrical communication with electrodes of the optically switchable device; a spacer (520, 1020, 1200, 1235, 1300, 1400, 1500, 1620); and a primary seal between the spacer (520, 1020, 1200, 1235, 1300,1400, 1500, 1620) and the lites (505, 1010, 1410, 1415), the primary seal hermetically sealing an interior volume of the insulated glass unit, wherein the spacer (520, 1020, 1200, 1235, 1300, 1400, 1500, 1620) is configured: to supply electricity to the optically switchable device via the one or more electrical power distribution components, wherein at least one of said one or more electrical power distribution components is either within the primary seal, or within the sealed interior volume of the insulated glass unit (500, 1000, 1215, 1305, 1400), and wherein the electricity supplied to said at least one of said one or more electrical power distribution components does not traverse the primary seal of the insulated glass unit (500, 1000, 1215, 1305, 1400); or both as (i) a structural element defining a portion of the primary seal around the interior volume of the insulated glass unit; and (ii) an electrical connector for the optically switchable device of the insulated glass unit, wherein the electrical connector comprises one or more wires (522, 523, 1017, 1205) that pass through a body of the spacer from outside the hermetic primary seal to the sealed interior volume of the insulated glass unit to electrically connect to the electrical power distribution components. first and second lites (505, 1010, 1410, 1415); an optically switchable device disposed on one of the lites; one or more electrical power distribution components in electrical communication with electrodes of the optically switchable device; a spacer (520, 1020, 1200, 1235, 1300, 1400, 1500, 1620); and a primary seal between the spacer (520, 1020, 1200, 1235, 1300,1400, 1500, 1620) and the lites (505, 1010, 1410, 1415), the primary seal hermetically sealing an interior volume of the insulated glass unit, to supply electricity to the optically switchable device via the one or more electrical power distribution components, wherein at least one of said one or more electrical power distribution components is either within the primary seal, or within the sealed interior volume of the insulated glass unit (500, 1000, 1215, 1305, 1400), and wherein the electricity supplied to said at least one of said one or more electrical power distribution components does not traverse the primary seal of the insulated glass unit (500, 1000, 1215, 1305, 1400); or within the primary seal, or within the sealed interior volume of the insulated glass unit (500, 1000, 1215, 1305, 1400), and both as (i) a structural element defining a portion of the primary seal around the interior volume of the insulated glass unit; and (ii) an electrical connector for the optically switchable device of the insulated glass unit, wherein the electrical connector comprises one or more wires (522, 523, 1017, 1205) that pass through a body of the spacer from outside the hermetic primary seal to the sealed interior volume of the insulated glass unit to electrically connect to the electrical power distribution components. (i) a structural element defining a portion of the primary seal around the interior volume of the insulated glass unit; and (ii) an electrical connector for the optically switchable device of the insulated glass unit, wherein the electrical connector comprises one or more wires (522, 523, 1017, 1205) that pass through a body of the spacer from outside the hermetic primary seal to the sealed interior volume of the insulated glass unit to electrically connect to the electrical power distribution components.