Southwire LN350 Rigid Conduit Locknut 3-1/2 Inch

Product Description

The SOUTHWIRE LN350 is a heavy-duty rigid conduit locknut designed to secure 3-1/2 inch threaded conduits and connectors to electrical junction boxes and enclosures. Built from heavy-gauge steel with a zinc electroplated finish, this locknut delivers reliable mechanical protection and solid grounding continuity at the connection point. The outer diameter measures 4.67 inches, and serrated teeth on the seating face bite into the box or enclosure surface to resist vibratory loosening over time. This hardware is suited for dry and damp location installations where conduit system integrity and secure grounding are required by code.

This locknut is used in commercial and industrial electrical installations wherever 3-1/2 inch rigid metallic conduit terminates at a junction box or enclosure. Electricians reach for this size on larger conduit runs feeding panels, motor control centers, and pull boxes. The zinc plating makes it appropriate for damp locations as defined under NEC installation guidelines, extending its use to mechanical rooms, utility areas, and covered outdoor enclosures.

Key Features

• 3-1/2 inch trade size fits standard threaded rigid conduit and connectors
• Heavy-gauge steel construction provides mechanical strength and grounding continuity
• Zinc electroplated finish resists corrosion in damp location environments
• Serrated teeth grip box and enclosure walls to prevent vibratory loosening
• 4.67 inch outer diameter for proper seating on standard knockout openings

Compatibility

Designed for use with 3-1/2 inch rigid metallic conduit (RMC) systems as an OEM-style fitting for securing conduit or connectors to electrical junction boxes and enclosures.

Installation Notes

Installation is performed by licensed electricians in accordance with NEC Article 344 for rigid metal conduit. De-energize all circuits in the enclosure before making conduit connections. Thread the locknut onto the conduit or connector and tighten firmly so the serrated teeth make solid contact with the enclosure wall to ensure a reliable equipment grounding path. Use a locknut wrench or spud wrench of appropriate size to achieve proper seating without damaging the teeth or enclosure surface.