Hubbell 1039 2-piece Knockout Seal 3 Inches

Product Description

The HUBBELL 1039 is a 2-piece knockout seal designed to close unused 3-inch knockout openings in electrical enclosures, junction boxes, and panel covers. It creates a secure, finished closure that protects internal wiring from dust, moisture, and physical contact. The two-piece design allows installation without access to the back of the panel, making it practical for retrofit and service work. Licensed electricians and electrical contractors install this seal as part of standard enclosure maintenance and code-compliance work.

This knockout seal is suited for residential and light commercial electrical installations where unused knockouts must be closed to meet NEC requirements for electrical enclosures. It is commonly used in load centers, junction boxes, outlet boxes, and other metal or plastic enclosures with 3-inch knockout openings. The split design makes it a practical choice for field installation on existing enclosures already in service.

Key Features

• 2-piece construction allows installation without rear access to the enclosure
• Fits 3-inch knockout openings in standard electrical enclosures
• Seals unused knockouts to meet NEC enclosure closure requirements
• Suitable for retrofit and new installation applications
• Compatible with both metal and plastic electrical enclosures

Compatibility

Designed as an OEM-style replacement seal for 3-inch knockout openings in standard residential and commercial electrical enclosures.

Installation Notes

Installation is performed by a licensed electrician. De-energize the electrical enclosure and verify the absence of voltage before beginning work. Insert the two-piece seal into the knockout opening from the front face of the enclosure without requiring rear panel access. Work must comply with applicable NEC requirements for closing unused enclosure openings.

Technical Specifications

• Knockout Size: 3 inches
• Piece Count: 2-piece

Standard Information

• Brand: HUBBELL
• Manufacturer Part Number: 1039