Engineered for versatility and efficiency, this cable overblowing junction box facilitates the installation of new cables or innerducts into existing duct systems of sizes 1-1/4 in., 1-1/2 in., and 2 in. SDR. Its innovative design includes an aluminum base and lid that create a pressurized air chamber, allowing for seamless attachment to an already occupied innerduct. Unique to this junction box are three cable seal slots, enabling secure exits for existing cables while accommodating various sizes with the included seals ranging from 7.5 mm to 20 mm. With a minimum flow acceptance of 700 cfm and a maximum operating pressure of 175 psi, it is an essential tool for ensuring efficient cable placement, particularly when utilizing a cable blowing machine for new installations.