Universal PVC-MC Cable Fitting with Adjustable Gripper
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Solution Overview
Problem
Existing liquid-tight electrical fittings are limited to connecting a single size of electrical cable, making them inadequate for accommodating the various nominal sizes of PVC jacketed MC and Teck 90 cables used in hazardous environments, including damp, dry, or wet locations, and embedded in concrete.
Innovation Solution
A liquid-tight and concrete-tight electrical fitting with a tubular body, gripper ring, grommets, bushing, sealing ring, locknut, and gland nut, designed to securely connect and ground PVC-MC and Teck 90 cables of multiple sizes to an electrical box or panel, featuring a range of grommets and bushings to accommodate different cable sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single-size electrical fitting is used, then the fitting design is simple and easy to manufacture, but it cannot accommodate multiple cable sizes
Solution Approach 1:
The electrical fitting is designed with multiple grommets of different sizes and a adjustable gripper ring mechanism that can accommodate various cable diameters. The fitting body includes a plurality of grommets with different inner diameters, allowing selection based on cable size, while the gripper ring can be positioned at different locations along the fitting body to secure different cable configurations, enabling a single fitting to serve multiple cable size requirements
Solution Approach 2:
The fitting is divided into multiple functional segments including the fitting body, gripper ring, bushing, and multiple grommets. Each component can be independently selected or adjusted based on cable size requirements. The grommets are provided in different sizes and can be individually chosen, while the gripper ring can be positioned at different segments along the fitting body, allowing modular adaptation to various cable dimensions without redesigning the entire fitting
2Adaptability or versatility
If multiple fitting types are stocked for different cable sizes, then all cable sizes can be accommodated, but inventory costs and complexity increase
Solution Approach 1:
A single universal fitting design incorporates multiple grommets of different sizes and an adjustable gripper ring mechanism that can accommodate various cable diameters. The fitting body includes a plurality of grommets with different inner diameters, allowing selection based on cable size, while the gripper ring can be positioned at different locations along the fitting body to secure different cable configurations, enabling a single fitting to serve multiple cable size requirements
Solution Approach 2:
The patent combines multiple size-specific components (grommets of different sizes, bushings, and gripper ring positions) into a single integrated fitting assembly. By merging these variations into one universal fitting type, electrical contractors can stock only this single fitting design while still having the capability to accommodate multiple cable sizes, thereby reducing inventory variety and associated costs
3Reliability
If a secure liquid-tight seal is provided, then protection against moisture and concrete penetration is achieved, but the fitting structure becomes more complex
Solution Approach 1:
The fitting employs grommets made of flexible elastomeric material that can be compressed to form liquid-tight seals around the cable and fitting body interface. The grommets are compressed between the bushing and the fitting body, creating a flexible sealing barrier that prevents moisture and concrete penetration while accommodating variations in cable size and shape without requiring complex rigid sealing mechanisms
Data Source
AI summary
An electrical fitting for securing PVC jacketed metal clad (PVC-MC) or Teck 90 electrical cable to an electrical box or panel in a liquid-tight and concrete-tight fit. The electrical fitting includes a tubular fitting body having a threaded inbound and outbound end, a gripper ring, one or more grommets, a bushing, a sealing ring, a locknut, and a gland nut. The grommet includes an outbound end with a tubular wall portion and an inbound end with a flange and an inner lip. The gripper ring includes a tubular base, one or more fingers extending from the base, and arcuate ends on the fingers. The fingers include a curvature which matches the curvature of the base. The fitting will accommodate a range of cable sizes and while providing a liquid-tight and concrete-tight connection and proper electrical grounding of the cables to an electrical box or panel.