Minerallac 55421J 3/8-16 X 1-1/4 Grade 5 Cap Screw

Product Description

The MINERALLAC 55421J is a 3/8-16 x 1-1/4 Grade 5 hex cap screw used to fasten structural and mechanical assemblies in electrical, HVAC, and plumbing installations. Grade 5 fasteners meet SAE J429 medium-carbon steel standards, offering tensile strength suitable for general trade applications. The coarse 3/8-16 thread pitch and 1-1/4-inch grip length make this screw a common choice for attaching brackets, equipment supports, and electrical enclosures where a standard hex head drive is required. Licensed tradespeople use this fastener in conduit support work, equipment mounting, and structural panel attachment.

This cap screw is suited for residential and light commercial applications where a Grade 5 fastener meets code and load requirements. It is commonly installed by electricians, HVAC technicians, and plumbers when securing equipment pads, mounting rails, junction boxes, and mechanical supports. The 3/8-16 coarse thread allows reliable engagement in steel tapped holes and standard hex nuts without special tooling.

Key Features

• 3/8-16 coarse thread for broad compatibility with standard tapped holes and hex nuts
• 1-1/4-inch length suitable for medium-depth fastening applications
• Grade 5 rating provides elevated tensile strength over Grade 2 fasteners
• Hex head drive compatible with standard combination and socket wrenches
• Appropriate for structural bracketing, equipment mounting, and enclosure attachment

Compatibility

Designed as a standard 3/8-16 x 1-1/4 Grade 5 hex cap screw for general trade fastening applications in electrical, HVAC, and plumbing work where this thread size and grade are specified.

Installation Notes

Installation is performed by licensed electricians, HVAC technicians, or plumbers using a standard 9/16-inch hex wrench or socket. De-energize any electrical equipment and shut off mechanical systems before fastening or removing hardware in live panels or equipment enclosures. Follow applicable NEC, IFGC, or IPC guidelines for fastener grade requirements on structural supports. Do not overtighten into tapped aluminum or thin sheet-metal threads, as stripping may occur with coarse-thread fasteners in softer base materials.

Technical Specifications

• Thread Size: 3/8-16
• Length: 1.25 inches
• Grade: Grade 5
• Head Type: Hex Cap
• UPC: 08593704211

Standard Information

• Brand: MINERALLAC
• Manufacturer Part Number: 55421J