Junction box installation costs $100 to $300 for parts and labor, depending on the installation location, accessibility, and the electrical box size, material, and indoor or outdoor rating. Plastic junction boxes for indoor wiring cost 50% to 80% less than metal boxes but. Buyers typically pay for a full panel replacement, including labor, materials, and permits. The article outlines cost ranges, per-unit pricing, and practical. 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 junction box. Can be with 1200pair and 2400pair capacity 2. Material: SMC or Cold rolled steel.