Electrical Box Knockout With Asymmetric Bridge Sections
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Solution Overview
Problem
Conventional knockout configurations in electrical outlet boxes result in burrs and reduced effective diameter after removal, making it difficult for electricians to install connectors and cables due to the deformation and size reduction of the cutout space.
Innovation Solution
The proposed knockout structure features a cutout with two bridge sections, one on each half of the perimeter, which allows for detachment without extending beyond the design diameter, minimizing burr deformation and maintaining the effective diameter for connector installation, achieved through a punching process with specific bridge section sizing and angled portions to enhance strength and reduce burr formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional knockout configurations are used, then the knockout can be removed to provide openings for conduits, but burrs and deformation occur that reduce the effective diameter and make connector installation difficult
Solution Approach 1:
The knockout is segmented from the electrical box wall through a controlled breaking process. The bridge sections are designed to break at specific locations during removal, allowing the knockout to be separated cleanly from the wall while maintaining the integrity of the opening edges and minimizing burr formation.
Solution Approach 2:
The knockouts are pre-formed with bridge sections that are designed to break at predetermined locations. The punching process creates a structure where the bridge sections will fail in a controlled manner during removal, ensuring that the knockout detaches cleanly without creating excessive burrs or deforming the opening.
2Strength
If the knockout is made stronger to maintain wall integrity, then the wall strength is improved, but the knockout becomes more difficult to remove and may cause excessive deformation
Solution Approach 1:
The bridge sections have different structural properties compared to the main knockout body. The bridge sections are designed with specific thickness and geometry to provide controlled weakness points that facilitate easy removal, while the main knockout body maintains sufficient strength for wall attachment. This local differentiation allows the knockout to be both strong when attached and easy to remove when needed.
Data Source
AI summary
A knockout structure for a wall of an electrical box includes a cutout that penetrates through the thickness of the wall to form a knockout on an interior of the cutout along a substantial perimeter of the knockout. The knockout structure also includes a first bridge section interrupting continuity of the cutout and maintaining a connection between the wall and the knockout. The knockout structure further includes a second bridge section interrupting continuity of the cutout and maintaining a connection between the wall and the knockout, the second bridge section being different than the first bridge section and on a same half of the perimeter of the knockout.