The Complete Guide to Electrical Boxes: Types, Materials, and Choosing the Right Gang Size

Selecting the right electrical box is crucial if you’re planning a residential or commercial electrical project. Electrical boxes are essential components that house wire connections, support light fixtures, switches, and outlets, and protect against electrical fires and accidental shocks. In this guide, we’ll break down the different types of electrical boxes, compare metal vs. PVC electrical boxes, explain gang sizes, and help you decide what type of box is right for your project.

Whether you're a DIYer, contractor, or electrician, this comprehensive guide will make it easy to buy electrical boxes online with confidence.

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Types of Electrical Boxes

When shopping for electrical boxes online, you'll find a variety of types designed for specific applications. Here are the most common types:

1. Standard Rectangular Boxes (Single-Gang Boxes)

• Ideal for: Light switches or single outlets

• Commonly made from PVC or metal

• Easy to install in drywall or masonry

• Perfect for small-scale residential electrical wiring

2. Double-Gang, Triple-Gang, and Quad Boxes

• Used for: Multiple switches or outlet combinations

• Allow you to mount two, three, or four devices side-by-side

• Available in both metal and plastic (PVC) versions

• Make wiring cleaner and more organized in kitchens, bathrooms, or commercial spaces

3. Round Ceiling Boxes

• Best for: Light fixtures or ceiling fans

• Typically installed in ceilings

• Choose boxes rated for the fixture weight you’re installing

4. Junction Boxes

• Purpose: Wire splicing and connections

• Often used for renovations and wiring extensions

• May remain hidden in attics or basements (accessible covers required by code)

5. Weatherproof Boxes

• Made for: Outdoor applications or wet locations

• Sealed with gaskets to prevent water intrusion

• Commonly made from non-corrosive metals or PVC

• Great for garden lighting, pool pumps, and garages

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Metal vs. PVC Electrical Boxes: Which One Should You Choose?

Choosing between metal electrical boxes and PVC electrical boxes depends on your wiring method, installation location, and local building code requirements.

🔩 Metal Electrical Boxes

Best used when:

• Installing exposed wiring (e.g., basements, garages, commercial settings)

• Using metal-clad (MC) cable or conduit systems (EMT, BX)

• Grounding continuity is required — metal boxes conduct electricity

Advantages:

• Extremely durable

• Fire-resistant

• Ideal for commercial and industrial use

Common Materials:

• Steel

• Galvanized steel

• Aluminum

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🧰 PVC Electrical Boxes (Plastic Boxes)

Best used when:

• Installing non-metallic (NM) cable such as Romex®

• Working on residential concealed wiring (inside drywall or wood framing)

• You want an easier, lightweight, and corrosion-resistant solution

Advantages:

• Non-conductive (reduces shock risk)

• Lightweight and easier to install

• Rust-proof and corrosion-resistant

Use caution: PVC boxes cannot be used with metal conduit without special connectors. They also lack the grounding capability of metal boxes.

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Understanding Electrical Box Gang Sizes

Gang size refers to how many devices (switches, outlets, etc.) a box can accommodate.

Common Gang Sizes:

• Single-Gang Electrical Box: Fits one switch or outlet

• Double-Gang Electrical Box: Fits two side-by-side

• Triple-Gang Electrical Box: Ideal for three devices

• Four-Gang Electrical Box: Supports four devices — used in control panels or larger kitchens

Tip: Always choose a deep electrical box or extra-capacity box if you’re dealing with multiple wires or larger devices like GFCIs or smart switches.

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How to Choose the Right Electrical Box

When shopping for the right box, consider:

1. Application Type: Outlet? Light switch? Ceiling fixture?

2. Location: Indoors, outdoors, in drywall, or on masonry?

3. Wiring Method: NM cable or conduit? (affects metal vs. PVC choice)

4. Device Count: How many switches or outlets will be in the box?

5. Code Compliance: Check your local code for box fill requirements

Final Tips for Buying Electrical Boxes Online

• Always include box volume and gang size in your selection

• Consider buying in multi-packs to save on high-volume jobs

• Look for UL-listed or code-compliant boxes for safety

Conclusion

Choosing the right electrical box for your project is more than just picking a size—it’s about ensuring safety, function, and compliance. Whether you need a metal junction box, a PVC outlet box, or a triple-gang switch box, knowing your materials and applications will help you get the job done right.

Shop now to explore a full range of PVC electrical boxes, metal electrical boxes, weatherproof boxes, and gang box sizes to match every residential or commercial need.