Waterproof distribution box manufacturers tell you that the way to waterproof an outdoor distribution box is to first choose a distribution box made of waterproof material, seal the cable entry points, apply silicone sealant, install a weatherproof cover, use outdoor rated sockets. Waterproof distribution box manufacturers tell you that the way to waterproof an outdoor distribution box is to first choose a distribution box made of waterproof material, seal the cable entry points, apply silicone sealant, install a weatherproof cover, use outdoor rated sockets. An electrical box sealant is a specialized material used to create an air-tight and water-resistant barrier around electrical enclosures and their penetrations. This practice is a fundamental part of maintaining a structure's envelope. It prevents the uncontrolled movement of air, moisture, and. Polylok offers the only catch basin and distribution box seal on the market that accepts multiple size pipes. After choosing your inlet/outlet holes and cutting them out, the seal is easy to install. This includes the rear wall, side panels, doors, door handle a d ventilation grille with climate filter for the air intake. However, particularly. Sealing electrical boxes is a task that seems simple, yet many people make considerable mistakes that can lead to serious consequences.