Mulberry 30290 Threaded Slotte...
IN STOCK (leaves warehouse same day if ordered before 3pm ET)
$0.42
Mulberry 30290 Threaded Slotted Round Closure Plug, Zinc Die-Cast, 1/2-Inch

Mulberry 30290 Threaded Slotted Round Closure Plug, Zinc Die-Cast, 1/2-Inch

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Model: 30290
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In Stock (leaves warehouse same day if ordered before 3pm ET)

$0.42
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Mulberry 30290 Threaded Slotted Round Closure Plug, Zinc Die-Cast, 1/2-Inch

The Mulberry 30290 Round Threaded Slotted Closure Plug is a die-cast zinc fitting engineered to seal unused 1/2-Inch conduit openings and knockouts in electrical enclosures and boxes, and is available in Bronze and Gray finishes to complement the surrounding installation. Its round, threaded body drives in with a standard slotted head, allowing quick installation and removal with a common flat-blade screwdriver, while the zinc die-cast construction delivers the strength and corrosion resistance electrical contractors expect from a quality closure plug. Use the 30290 to maintain a clean, protected enclosure whenever a knockout or threaded opening is not currently in service, and back it out again later if that opening needs to be put back into use.

Key Features

  • Trade Size: Sized 1/2-Inch to fit standard conduit knockouts and threaded openings in electrical enclosures and boxes.
  • Durable Construction: Zinc die-cast body resists corrosion and holds up to repeated installation and removal in the field.
  • Threaded, Slotted Design: Round threaded body with a slotted head installs and backs out quickly using a standard flat-blade screwdriver.
  • Closure Function: Seals unused conduit openings and knockouts to keep enclosures clean, protected, and free of debris intrusion.
  • Round Profile: Low-profile round head sits flush against the enclosure surface for a neat, finished appearance.
  • Color Options: Available in Bronze and Gray to complement the finish of the enclosure or panel.
  • Reusable Design: Threaded engagement allows the plug to be removed and reinstalled if the sealed opening is later needed for conduit entry.

Technical Specifications

  • Product Material: Zinc Die-Cast
  • Trade Size: 1/2-Inch
  • Color Options: Bronze, Gray

Typical Applications

  • Electrical Enclosure and Panel Knockout Sealing
  • Conduit System Closures
  • Junction and Switch Box Closures
  • Commercial and Industrial Electrical Installations
  • Service Equipment and Panelboard Openings
  • Renovation and New Construction Wiring Projects

Why Mulberry?

Mulberry builds electrical fittings like the 30290 closure plug from zinc die-cast material for long-term durability in demanding installation environments, and offers it in Bronze and Gray to fit the look of the surrounding enclosure. Choosing a properly sized, correctly threaded closure plug helps keep every enclosure clean, protected, and code-compliant, whether it is used on a new installation or during a service upgrade. Shop Mulberry electrical fittings at ZenSupply for reliable, well-made components trusted by electrical professionals on commercial and industrial jobs.

Manufacturer Resources

Mulberry Full Line Catalog

Product Specs

Product Type:
Closure Plug
Connection Type:
Threaded
Product Material:
Zinc Die-Cast
Product Size:
1/2-Inch
Department:
Electrical
Product Group:
Boxes & Enclosures
Product Subgroup:
Enclosure Accessories

Mulberry 30290 – Frequently Asked Questions

1) Will the Mulberry 30290 closure plug fit a 1/2-inch knockout in a standard electrical box?
The Mulberry 30290 is a 1/2-inch trade size closure plug with a threaded body, so it threads into 1/2-inch threaded openings and knockouts in enclosures and boxes. Trade size 1/2 is the most common conduit knockout on junction boxes, switch boxes and panelboards, so it covers the bulk of what you will run into. If your opening is a larger trade size, this plug is the wrong part.
2) Is a threaded closure plug the right choice, or should I use a snap-in knockout seal?
Use a threaded plug like the 30290 when the opening is actually threaded, such as a hub or a threaded entry on a cast or die-cast enclosure. It drives in with a flat-blade screwdriver and backs out again if you later need that opening for conduit entry. A snap-in or press-fit seal is the part for a plain punched knockout in sheet metal with no threads. Matching the plug to the opening type is what decides whether it holds.
3) What color options does the Mulberry 30290 plug come in, and which part number is which?
Two colors. Gray is part number 30290 and Bronze is 30290Z. The choice is cosmetic, letting the plug blend with the enclosure or panel finish, so on exposed interior or architectural work order the one that matches the surrounding device plates.
4) Is the 30290 plug durable enough for outdoor or damp industrial enclosures?
The body is zinc die-cast, which resists corrosion and takes repeated installation and removal in the field, and it is used on commercial and industrial installations including service equipment and panelboards. It is not a plastic plug that will crack when you back it out. Specify a gasketed or sealing fitting if the enclosure rating depends on a watertight entry.
5) Can I take the plug back out later if I need to run conduit into that opening?
Yes. The threaded engagement and slotted head mean you can back the 30290 out with a standard flat-blade screwdriver and put the opening back in service, then reinstall the plug later if the run changes. That makes it practical for property managers and MRO shops stocking a few for panel changes rather than one-time sealing.
6) Do I need any gasket or extra hardware to install the Mulberry 30290?
No additional hardware. The plug threads directly into the 1/2-inch opening and seats on its own round, low-profile head, which sits flush against the enclosure surface. The only tool needed is a flat-blade screwdriver.
How fast can I get the Mulberry 30290 delivered?
Most orders ship the same day from our distribution partners, with quick delivery throughout the continental U.S. Need it urgently? Contact Us for expedited shipping options.
Can I return it if it doesn’t work for me?
Yes—ZenSupply offers a hassle-free return policy. If the product isn’t the right fit, reach out to our support team for a return authorization or setup a return by following our return instructions.
Does the Mulberry 30290 come with a warranty?
Absolutely. The Mulberry 30290 is backed by a manufacturer’s warranty. For full warranty terms, check the product documentation or Contact Us.
How do I get technical support or installation help for the Mulberry 30290?
You can call, text, or email our expert support team for fast answers. We’re here to help with product selection, installation tips, and troubleshooting. Contact Us
Why buy the Mulberry 30290 from ZenSupply?
ZenSupply makes it easy to get the commercial door hardware you need—fast shipping, expert support, and rewards on every order. Our team is always ready to help you choose the right product for your project.
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