Arlington 408 Steel Locknut 3 Inch Conduit

Product Description

The ARLINGTON 408 is a 3-inch steel locknut designed to secure conduit connectors and bushings to electrical enclosures, junction boxes, and panel knockouts. The locknut threads onto the male threads of a conduit fitting and is tightened against the enclosure wall to create a rigid, low-resistance mechanical connection. It is a standard consumable in electrical rough-in work and is installed by licensed electricians on both commercial and residential projects. The steel construction provides the mechanical strength needed to maintain a solid, code-compliant grounding path through metallic conduit systems.

The ARLINGTON 408 is used wherever 3-inch conduit terminates at an enclosure — including panelboards, wireways, junction boxes, and pull boxes. It is suited for rigid metal conduit (RMC), intermediate metal conduit (IMC), and compatible threaded fittings at the 3-inch trade size. This fitting is a staple of high-ampacity feeder runs and large service entrance installations where 3-inch conduit is common.

Key Features

• 3-inch trade size fits standard 3-inch conduit connector threads
• Steel construction delivers mechanical strength and a reliable grounding continuity path
• Threaded design allows hand-start installation with wrench or locknut wrench tightening
• Compact profile seats flush against enclosure walls for clean terminations
• Lightweight at 0.162 pounds, minimizing added load at enclosure knockouts

Compatibility

Designed as an OEM-style replacement and standard-use locknut for 3-inch trade size metallic conduit fittings in commercial and residential electrical installations.

Installation Notes

Installed by licensed electricians in accordance with NEC requirements for securing conduit fittings to enclosures. De-energize the panel or enclosure before working at any knockout entry point. Thread the locknut onto the fitting by hand, then tighten firmly with a locknut wrench or flathead screwdriver and hammer to ensure solid metal-to-metal contact for grounding continuity. Do not overtighten to the point of deforming the enclosure wall.

Technical Specifications

• Trade Size: 3 inches
• Material: Steel
• Weight: 0.162 pounds
• UPC: 01899700408

Standard Information

• Brand: ARLINGTON
• Manufacturer Part Number: 408