Electro Hardware S521M17F16G Circuit Board Spacer

Product Description

The ELECTRO HARDWARE S521M17F16G is a round, female unthreaded circuit board spacer designed to create consistent standoff clearance between a PCB and its mounting surface. Made from Nylon Grade 101 and meeting the MIL-P-17091B fastener standard, this spacer accepts a No. 6 screw and measures 0.375 inches overall length with a 0.25 inch outside diameter and a 0.141 inch inside diameter. The uncoated finish is appropriate for standard electronic assembly environments. Electricians, electronic technicians, and panel builders use these spacers during control board installations to maintain proper board-to-chassis spacing and prevent electrical contact with mounting surfaces.

This spacer is suited for residential and commercial applications wherever printed circuit boards require secure, insulated standoff mounting. Common use cases include HVAC control board assemblies, electrical panel subassemblies, and industrial control enclosures. Its nylon construction provides electrical insulation between the board and chassis, which is especially useful in low-voltage control circuits. The No. 6 screw thread size makes it compatible with a wide range of standard PCB mounting hardware used in trade equipment.

Key Features

• Nylon Grade 101 construction provides electrical insulation and corrosion resistance
• Meets MIL-P-17091B fastener standard for consistent dimensional quality
• Female unthreaded body accepts No. 6 screws for straightforward installation
• 0.375 inch overall length with tight length tolerance of -0.005 to 0.005 inches
• Inside diameter tolerance of 0.000 to 0.010 inches for reliable screw fit
• Uncoated bright finish compatible with standard PCB assembly processes

Compatibility

Designed as an OEM-style replacement or new-installation spacer for circuit board assemblies requiring a No. 6 screw, round body, female unthreaded standoff with a 0.375 inch overall length and 0.25 inch outside diameter.

Installation Notes

Installation is typically performed by electricians or electronics technicians during control board assembly or replacement. Always de-energize the equipment and discharge any stored electrical energy before handling circuit boards or mounting hardware. Use a hand screwdriver rather than a power driver to avoid over-torquing nylon spacers, which can crack or deform under excessive force. Follow applicable NEC guidelines for low-voltage control wiring when reassembling the control panel after spacer installation.