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. This article explains how to safely air seal electrical boxes to tighten your home's thermal envelope. Electrical penetrations are often responsible for holes in the most critical locations in your envelope, making them a prime target when your goal is to air seal your home. However, particularly. These “holes” allow air, heat, and moisture to move into or out of the home. The openings can also be entry points for dust, insects and, in the case of larger gaps, even rodents. When a hole is cut into drywall for an electrical box, it creates a direct breach in the home's protective envelope, allowing. For ceiling-mounted electrical boxes, install the electrical box in the ceiling drywall, then caulk around the base and caulk all holes in the box with fire-retardant caulk. Confirm power is off with a voltage tester. Make sure the junction box has been properly installed and "rough-wired" all wires should be run through the box and secured before installing BOX SHELL. As such, air-sealing electrical boxes and related.
