Various connection methods for concealed wiring junction boxes

Concealed junction boxes can be safely installed behind walls or fixtures by selecting the right box, mounting it securely, making proper splices, and ensuring accessibility for future maintenance.

Choosing the Right Box

Select a junction box that matches the wiring type and environment. Plastic boxes are suitable for non-metallic cables in dry indoor locations, while metal boxes are preferred for conduit or areas requiring extra durability. Ensure the box is large enough to accommodate all conductors, splices, and connectors, following code requirements for cubic inches per wire.

Preparing the Installation

Turn off power at the main breaker and verify with a non-contact voltage tester. Mark the location for the box, ideally behind a fixture, TV mount, or furniture to conceal it. Cut an opening in the wall or ceiling just large enough for the box, ensuring it aligns with a stud or joist for secure mounting.

Mounting the Box

Attach the box to a stud or joist using screws or nails, keeping the front edge flush with the finished wall surface. For metal boxes, remove knockouts and install cable clamps; plastic boxes often have internal clamps.

Running and Preparing Wires

Feed cables through the clamps, leaving about 6 inches of conductor inside the box for splicing. Strip approximately 3/4 inch of insulation from each wire end.

Making Connections

Match wire colors: black (hot) to black, white (neutral) to white, and green/bare (ground) to green/bare. Twist wires together and secure with approved wire nuts. For metal boxes, connect a grounding pigtail to the box screw.

Push spliced wires neatly into the box, avoiding overstuffing.

Concealing the Box

Position the box behind a fixture, TV mount, or panel to hide it while keeping it accessible for future inspection. If the box is high on a wall, ensure there is enough slack in the cable; you may need to replace a section of cable to meet minimum wire length requirements. Cover the box with a removable panel or blank cover that blends with the wall finish, maintaining code compliance.

Safety and Code Compliance

Always follow local electrical codes regarding box placement, size, and accessibility. Avoid burying splices without a junction box unless specifically allowed by local regulations. Wear protective gloves and eye protection during installation.

By carefully selecting the box, mounting it securely, making proper splices, and concealing it behind fixtures or panels, you can achieve a safe, durable, and visually unobtrusive junction box installation.