Junction box costs range from low‑price indoor models ($10‑$60) to weatherproof units ($70‑$450), with installation averaging $100‑$300 depending on location and materials. If you're planning any electrical work, one of the small but important items on your list will be the. A 10kV junction box is an essential component in medium-voltage electrical systems, providing a secure and insulated enclosure for connecting, branching, or terminating high-voltage cables. At first. Choose from our selection of junction boxes, including over 2,800 products in a wide range of styles and sizes. 35KV series heat-shrinkable cable terminals and joints have the funetion of water-proof, the stress control, shield and insulation.