A hinge 4 for an aircraft power distribution system unit comprises: a first hinge member 11 for connection to a first housing part (e.g. main body) of the unit and a second hinge member 10 for connection to a second housing part (e.g. door) of the unit. The first and second hinge members comprise an electrically conductive material and are connectable to one another to establish an electrical connection between the hinge members and to allow relative rotation between the hinge members. The hinge may be positioned inside the housing parts. The first hinge member may comprise a receptacle (e.g. hyperboloid socket) while the second hinge member may comprise a cylindrical protrusion which engages the receptacle and wherein the longitudinal axis of the protrusion coincides with a rotation axis of the hinge. The first and/or second hinge member(s) may be electrically insulated from the exterior of the unit and may be connected to, or formed integrally with, a bus bar for distributing electrical power to one or more electrical components.