Screw Size For Electrical Box (Quick Guide)

The required electrical screws are usually included in the package when purchasing new electrical boxes or configurations. However, if you need to replace an electrical box or have misplaced the original screws, you may have to buy new screws to attach your electrical box safely. With so many screw options in the market, it can be difficult to determine the correct size and type of electrical screw.

The most commonly used screw size in an electric box is a 6-32 flathead screw. For more demanding applications like ceiling lighting and ceiling fans, an 8-32 screw is better suited. Ground screws in electrical boxes are always 10-32 and should be painted visibly green.

It’s important to use flathead screws as they will sit flush with your electrical application. The screw head can be either Philips or slotted, but electricians prefer slotted screws.

When working in electrical applications, use stainless steel or zinc-coated screws. These screw materials are the safest and help keep the physical, and electrical box in good condition.

How Is a Screw Measured?

The way screws are measured can be confusing at first glance. There are three key measurements for screw sizing: gauge, threads per inch, and length.


The gauge measurement determines the diameter of the screw. Screw diameters come in various sizes to accommodate different projects, with #6 gauge being the most commonly used size for electrical work, including electrical boxes. The gauge measurement is the first number listed in the screw size.

Threads Per Inch

Threads per inch determine the number of threads in a one-inch screw shaft. For electrical boxes, electricians usually recommend using 32 threads per inch. This number is always listed after the gauge measurement.


The screw length is the final measurement in the screw description. It is an important measurement, especially when working with electrical boxes. For standard outlets or switches, a one-inch screw is typically the right length to use.

How To Choose An Electrical Box

What Screw Material Should Be Used for Electrical Boxes?

It is crucial to use the appropriate screw material and size when working with electrical boxes. Improper selection of screw material can result in the accidental damage of an electrical box or improper electrical conductivity, which can be hazardous.

Always opt for stainless steel screws while working with electricity. These screws are specifically designed for electrical use and are safe to use. Avoid using drywall screws and sheet metal screws, as they can cause more harm than good and potentially damage your electrical boxes. It is essential to note that drywall screws and sheet metal screws do not meet electrical code requirements in most residential homes across the country.

What Screws Should I Use For a Cover Plate?

A faceplate is a component of an electrical installation that covers switches or outlets to protect them and keep them safely inside the wall. The screws used for faceplates are typically oval-shaped with a flat head and are usually 6-32 with a length of around 5/16 inches. If covering an empty outlet box, a screw with a length of one inch can be used.

Determine the appropriate screw size for 1/2 inch cement board.

What Screws Should I Use For Switches and Outlets?

When mounting electrical switches and outlets on the studs in your wall, it’s essential to ensure a sturdy connection.

You can use a 6-32 screw for the electrical outlet, which comes packaged with most new electrical outlets. However, to make sure the screw is securely anchored to the studs in your wall, try using a larger one-inch screw.

What Screws Should I Use For Recessed Outlets?

In the case of a thicker wall, a recessed outlet may need to be used. This outlet type has an extended electrical box to accommodate the added thickness, which requires longer screws. Typically, a 6-32 1.5-inch length screw works best to attach a recessed outlet.

While more extended screw options are available in the 6-32 size, never use a screw longer than two inches to attach an electrical box. Keep in mind that the deeper recessed box will also require longer screws than usual to attach the face cover plate securely.

What Screws Should I Use For Ceiling Lights?

Round electrical boxes are often used for ceiling lights and ceiling fans because of their installation style. These boxes require different screws to hold them in place compared to regular electrical boxes.

For a round electrical box, it’s recommended to use an 8-32 screw with a slightly larger diameter and better suited for ceiling applications.

What Screws Should I Use for Exterior Electrical Applications?

Exterior outlet boxes are a safe and convenient way to add power and electricity to the outdoors. These outlets are typically identical to interior outlets but with added insulation and weather protection. To attach an exterior outlet, a 6-32 screw is recommended.

However, keep in mind that some exterior outlets may be installed in extra-thick walls, which may require longer electrical screws of 1.5 inches or 2 inches. Always use stainless steel screws for exterior applications.

What Is A Ground Screw?

The purpose of a ground screw in an electrical box is to keep the ground wire in place and ensure the electrical outlet is safe and grounded. Usually, this screw is thicker with a hex head and painted green to make it easily identifiable.

Ground screws are usually hex-head screws in a slot head or Philips style. They are typically 10-32 in size and 5/16 inches long. To pass the electrical code in most residential areas, the ground screw must be painted green.

Can I Use Any Screw as a Ground Screw?

If the available ground screw options do not fit or work, using any 8-32 screw with a washer for functionality’s sake is possible. Although using a simple stainless steel screw with a washer attached may function safely, it will not pass electrical code. Electricians often prefer this setup to meet their needs better than using a hexhead screw to meet code requirements.

Where Can I Buy Electrical Screws?

Many DIYers and homeowners find electrical screws to be an easily accessible and commonly used material. They can be found at local hardware stores such as Home Depot or Lowe’s and are available in packs of two or in bulk for larger home projects.

Besides hardware stores, electrical screws can be purchased online from retailers such as Amazon. When buying online, you may have more options for sizes and materials, and packages are often sold in larger bulk quantities. However, the downside of online orders is the wait time for delivery, which can be inconvenient when working on an ongoing project.

Related Questions

Can I use plastic screws in electrical boxes?

There is a range of materials that screws can be made of, making them versatile for various applications. Typically, screws are made of metal, but plastic screws can be used for specific purposes. However, remember that plastic screws may not be as durable as metal screws and may not withstand the weight.

How Much Weight Can an Electrical Box Screw Hold?

Knowing the weight capacity of your screws is crucial to ensure the safety and security of your electrical box. A 6-32 electrical screw can typically support up to 12 pounds. For heavier applications, multiple screws may be necessary to support the weight.

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