Southwire MR10 Reducing Washer 1.5 X 1 Inch

Product Description

The SOUTHWIRE MR10 is a reducing washer designed to adapt a larger electrical knockout opening to accept a smaller conduit fitting or connector. This type of reducer fits between the fitting locknut and the enclosure wall, filling the gap created when a smaller trade-size conduit entry is used in a larger knockout. Electricians use reducing washers during panel, junction box, and enclosure work to maintain a secure, code-compliant entry point without cutting a new knockout. The MR10 steps down from a 1.5-inch opening to a 1-inch fitting size.

This reducing washer is suited for residential and light commercial electrical installations. Common applications include load centers, junction boxes, meter sockets, and other metallic enclosures where knockout sizes do not match the conduit or connector being used. It is installed at the point of conduit entry and works with standard locknuts and connectors in both rigid and flexible conduit systems.

Key Features

• Reduces a 1.5-inch knockout to accept a 1-inch trade-size fitting
• Flat washer profile seats flush against enclosure wall for a tight fit
• Compatible with standard locknuts used in metallic conduit wiring systems
• Supports code-compliant knockout fill in panels and junction boxes

Compatibility

Designed as an OEM-style replacement reducing washer for 1.5-inch to 1-inch electrical knockout applications in residential and commercial enclosures. Also referenced as Madison MR-10 and RW-150100.

Installation Notes

Installation is performed by a licensed electrician. De-energize the panel or enclosure and verify lockout-tagout procedures are followed before beginning work. Slide the reducing washer over the connector body and seat it flat against the inside or outside of the enclosure wall before tightening the locknut. Installations must comply with applicable NEC requirements for conduit entry and enclosure fill.

Technical Specifications

• Knockout Opening (Large Side): 1.5 inches
• Fitting Size (Small Side): 1 inch
• Type: Reducing Washer

Standard Information

• Brand: SOUTHWIRE
• Manufacturer Part Number: MR10