Morris 21798 Type S With Screw and Bar Knockout Seal, 3-1/2"

Product Overview

The Morris 21798 is a 3-1/2" Type S knockout seal with a pre-assembled set screw and backer bar for closing unused openings in electrical boxes, panels, and enclosures.

Constructed from galvanized steel, this screw-and-bar seal is designed for standard, air-tight, or dust-tight applications and installs without removing box devices or covers.

Key Features

• Pre-assembled set screw with backer bar slides into open knockouts—no removal of devices or covers required
• Intended for standard, air-tight, or dust-tight applications
• Made of galvanized steel for field durability
• Trade size: 3-1/2" (catalog no. 21798)

What this part does

The Morris 21798 is a knockout seal designed to close a 3-1/2" knockout opening in electrical boxes, panels, and enclosures. Its set screw and backer bar arrangement secures the seal in place and protects exposed wiring while helping preserve the enclosure’s intended degree of dust or air tightness.

• Closes unused knockout openings
• Protects exposed conductors from contact and contamination
• Helps maintain air-tight or dust-tight characteristics when used as specified

Where to use it

Use the 21798 in electrical junction boxes, device boxes, control panels, and metal enclosures wherever a 3-1/2" knockout remains unused. The product is specified for standard, air-tight, or dust-tight applications when installed correctly.

• Suitable for boxes, panels, and enclosures
• Intended for applications requiring a screw-and-bar type knockout seal

Installation

Installation is performed by sliding the pre-assembled screw and backer bar into the open knockout; the design allows installation without removing box devices or covers. The plug is then snapped or threaded into the knockout as applicable.

• Pre-assembled screw and backer bar slides on open knockout holes
• Snap or thread the plug into the open knockout per site practice

Materials and durability

The 21798 is constructed of galvanized steel for corrosion resistance and field durability. The galvanized finish is selected to provide a durable protective coating appropriate for typical electrical enclosure environments.

• Material: galvanized steel
• Designed for durability in general electrical installation environments

Before You Order

Confirm the model number (Morris 21798) and that a 3-1/2" trade-size knockout seal is the correct fit for your box or enclosure before ordering.

• Verify the knockout diameter and enclosure requirements prior to purchase.
• Confirm quantity required for the project.

Ordering from Lumera Electric

Check the purchasing options shown on the Lumera Electric product page for Morris 21798 Type S With Screw and Bar Knockout Seal, 3-1/2". For project quantities or additional ordering requirements, use Request a Quote and provide the required quantity.