Abstract: An item may include fabric or other materials formed from intertwined strands of material. The item may include circuitry that produces signals. The strands of material may include non-conductive strands and conductive strands. The conductive strands may carry the signals produced by the circuitry. Conductive strands may be insulated by insulating strands that have been wrapped around the conductive strands. Insulating strands may include strands of fusible material that softens when heated to the appropriate temperature. Fusible insulating strands may be interspersed with insulating strands of a different material. The fusible insulating strands may be heated such that the fusible material melts and fills gaps between the other insulating strands, thereby forming a watertight covering over the conductive strand. The fusible insulating strands may be used to insulate electrical connections between conductive strands and/or between electronic components and conductive strands.