A method for coupling ends of two insulated conductors includes coupling a core of a first insulated conductor to a core of a second insulated conductor. Exposed portions of the cores are located inside a box with an open top. Electrically insulating powder material is placed into the box and a first plunger is inserted through the open top of the box to compact the powder material. Additional electrically insulating powder material is placed into the box and a second plunger is inserted through the open top of the box to compact the powder material into compacted powder material that surrounds the exposed portions of the cores. The compacted powder material is formed into a substantially cylindrical shape. A sleeve is placed over the compacted powder material and coupling the sleeve to the jackets of the insulated conductors.