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. Waterproof distribution box moisture typically originates from condensation, gasket degradation, or cable entry leakage. Moisture inside a waterproof distribution box almost always traces back to one of three root causes: seal degradation, condensation buildup, or mechanical breach. Identifying. Selecting and installing the right protective enclosure ensures long-term electrical safety in demanding environments. Usually, rubber sealing rings or sealants are used for sealing to effectively prevent the intrusion of rainwater, sand and dust. In addition, for some special interfaces. Waterproofing of outdoor electrical boxes is critical to protecting electrical components from moisture and ensuring safety.