An electrical box is a protective enclosure used to contain wiring connections for devices like outlets, switches, and fixtures. Unless the device is one of the few that includes its own enclosed wiring, it will likely require an electrical box to house and protect its connections. Electrical boxes help prevent electrical hazards (e.g. shocks and fires). They also help organize the electrical cables. Article 300. 15 of the NEC suggests that all splices, junctions, and terminations are supposed to be enclosed in the electrical box. In this guide, we will look into the applications for each subtype of electrical box.

Standard Rectangular Box

Best for: Compact installations in walls with single switches or outlets.

A standard rectangular box, also known as a single-gang box, is one of the most common types of electrical boxes. It’s typically used to house a single switch or outlet. This is the versatile box you need if nothing is particularly special about your installation.

Here are some of the details on the standard rectangular box:

• It has a rectangular shape and usually measures around 2 x 4 inches. This size fits all standard outlets and switches.
• Standard boxes are available in both metal and plastic. Plastic is lighter and is resistant to corrosion. Metal is more durable and can serve as a grounding conductor.
• Can be used in new construction (mounted on studs before drywall) or as an "old work" box installed into existing walls.
• Can have built-in cable clamps for securing NM-B cables.

Square Box (4-Inch Square Box)

Best for: Connecting or splicing multiple wires safely in one location.

A 4-inch Square Box is designed as a junction box, meaning it’s used primarily to connect (or "splice") multiple electrical wires together. This allows circuits to branch off safely in different directions.

Compared to a rectangular box, this one offers more space. Because it’s larger than standard boxes, a 4-inch square box has enough space for several wires without overcrowding, making it ideal for handling complex wiring setups in commercial buildings and industrial sites. This metal box can be fitted with covers or mud rings to hold switches or outlets.

Octagon Box

Best for: Ceiling or wall installations for small light fixtures or junction points with a maximum weight capacity of 50 pounds.

An octagon box is an electrical box shaped with eight sides, typically used in ceiling or wall installations. It’s ideal for housing small light fixtures, smoke detectors, and fan/light combos or for serving as a junction point where multiple electrical wires connect.

Available in various depths and usually made of metal, octagon boxes are sturdy and often feature multiple knockouts (pre-punched holes) to accommodate wiring from different directions. They offer ample room for wiring connections, especially in fixtures requiring several cables or heavier mounting.

Octagon boxes are deeper than standard rectangular boxes, meaning you can add more wiring there than needed. If you need more room or a flexible option for wiring, this is the box for you.

Round Pan Box

Best for: Lightweight ceiling fixtures, smoke detectors, or small junctions up to 6 pounds.

A round pan box is a shallow, circular box commonly used for ceiling-mounted installations where space is limited, such as for small light fixtures or smoke detectors. Its compact size makes it ideal for areas that don’t require a deep box, like surface-mounted lighting. Round pan boxes are often made of metal to provide stability and are typically installed directly onto ceiling joists for secure support. These boxes are usually 4 inches in diameter and about 1/2 to 3/4 inch deep.

Weatherproof Box (Outdoor Box)

Best for: Outdoor electrical installations to protect from environmental factors like weather and moisture.

A weatherproof box is mounted on exterior walls or roofs. They are used to install outdoor outlets and lighting. They are often rated as NEMA 3R or NEMA 4 for weather resistance thanks to having tighter seals than regular boxes.

Weatherproof boxes are from corrosion-resistant materials like aluminum, stainless steel, or heavy-duty PVC. They also have rubber or foam gaskets around openings and seams, ensuring a watertight seal.

Many weatherproof boxes come with mounting brackets and are installed directly onto exterior walls. They may also include knockouts for conduit connections.

Outdoor boxes are commonly used in patios, garages, and gardens.

Ceiling Fan Box

Best for: Safely supporting ceiling fans and heavy light fixtures.

A ceiling fan box is typically rated to support up to 70 pounds for ceiling fans and around 90 pounds for static (non-moving) fixtures. Ceiling fans need their brand of electric boxes because they are heavy and constantly moving.

Ceiling fan boxes are made of sturdy metal or reinforced plastic. They are mounted directly to ceiling joists or other secure framing for stability. Ceiling fan boxes often include threaded holes or braces for securely attaching fan hardware, preventing wobbling or sagging over time. Unlike standard boxes, they’re built to withstand the vibration and motion of fan blades.

They are usually round or octagonal, designed to fit seamlessly with ceiling fans or light fixtures. They typically measure about 4 inches in diameter and vary in depth, usually between 1/2 inch and 2 inches deep.

New Work Box

Best for: New construction projects with open walls for direct attachment to studs before drywall.

A new work box is an electrical box designed specifically for installation in new construction before walls are closed up. These boxes are usually plastic but can come in metal and are mounted directly to wall studs or ceiling joists. They feature side or back mounting brackets or nailing tabs, which make it easy to attach them firmly to the framing structure.

Since the new work box is installed before drywall, you can plan the exact placement of cables without cutting into the wall. This makes them great for new buildings or remodeled apartments.

Old Work Box

Best for: Remodeling or retrofit projects with finished walls.

An old work box is designed for installation in existing walls without needing to open them up. It’s fitted directly into cut wall openings and secured with side clips or "wings" that hold it in place. This makes it ideal for adding outlets, switches, or fixtures in finished spaces.

2-Gang Box

Best for: Installing two switches or outlets side by side.

Holds two devices, like switches or outlets, side by side. Common in areas needing separate controls for lights or outlets. Often used in living rooms or bedrooms with layered lighting. Available in both metal and plastic, with options for new work or old work.

3-Gang Box

Best for: Housing three switches or outlets in a single location.

Built to handle three devices, making it ideal for larger rooms with multiple lighting zones or switches for different fixtures.

4-Gang Box

Best for: Accommodating four switches or outlets together in one spot.

Designed for spaces that require four devices in one place, often seen in high-use areas like kitchens or entryways where several controls (lights, fans, outlets) are needed. Is usually made of stainless steel metal, plastic variants are not common, as these are supposed to hold extra wiring space.