Electro Hardware S545-M10-F21-H Circuit Board Spacer

Product Description

The ELECTRO HARDWARE S545-M10-F21-H is a round, female unthreaded circuit board spacer designed to create precise standoff clearance between a PCB and a mounting surface. Machined from Grade 2 steel with a zinc-plated finish per ASTM B633 and QQ-S-633 Type 1, it delivers corrosion resistance suitable for electronic enclosure environments. The spacer measures 0.75 inches overall length with a 0.25-inch outside diameter and a 0.171-inch inside diameter sized to clear a No. 8 screw shank. Licensed electricians and electronics technicians install these spacers during control board mounting in HVAC units, electrical panels, and industrial equipment assemblies.

This spacer is appropriate for residential and commercial applications wherever No. 8 fasteners are used to mount circuit boards in enclosures, junction boxes, or equipment chassis. Common install scenarios include HVAC control board replacement, motor drive panel assembly, and automation enclosure builds where consistent board standoff height is required to maintain clearance and prevent short circuits against metal surfaces.

Key Features

• Female unthreaded body accepts a No. 8 screw shank through the 0.171-inch inside diameter bore
• 0.75-inch overall length provides consistent standoff height for PCB mounting
• Grade 2 steel construction with zinc-plated finish meets ASTM B633 and QQ-S-633 Type 1 standards
• Round body profile with 0.25-inch outside diameter fits standard board mounting footprints
• Inside diameter tolerance of 0.000 to 0.010 inches and length tolerance of -0.005 to 0.005 inches for controlled fit

Compatibility

Designed as an OEM-style replacement or new-installation spacer for circuit board mounting applications using No. 8 fastener hardware in inch-measurement systems.

Installation Notes

Installation is performed by licensed electricians or qualified electronics technicians. De-energize and lock out the equipment before removing or installing any circuit board hardware. Ensure the mating screw length accounts for the full 0.75-inch spacer height plus board thickness to achieve proper thread engagement. Follow applicable NEC requirements for enclosure work and do not over-torque fasteners through an unthreaded spacer bore, as the bore provides clearance only and does not carry thread load.