Non-hardening electrical putty, also known as duct seal compound or mastic, is the preferred material for sealing wire entries directly inside the box. This pliable, non-toxic compound is easily molded by hand to form a plug around the wire bundle where it passes through the back. Learn how to seal electrical enclosures effectively to protect equipment from moisture, dust, and harsh environments. Step-by-step guide and expert tips. This practice is a fundamental part of maintaining a structure's envelope. It prevents the uncontrolled movement of air, moisture, and. BOX SHELL is a patented enclosure system that completely seals electrical junction boxes — eliminating air infiltration, reducing energy loss, and meeting LEED, WELL, and Passive House standards. Effective sealing involves material compatibility, proper gasket selection, and application techniques. Air leakage from electrical. Sealing products are specifically designed to ensure the integrity of electrical cables, panels, and boxes, providing protection against adverse environmental effects. These products help prevent moisture, dust, pollutants, and other harmful substances from entering electrical systems, ensuring.