An electrical box is a protective enclosure used to contain wiring connections for devices such as outlets, switches, and fixtures. Unless the device is one of the few that has its own enclosed wiring, it will likely require an electrical box to house and protect its connections. Electrical boxes help prevent electrical hazards (such as shocks and fires). They also help organize electrical cables. Section 300.15 of the NEC suggests that all connections, connections and terminations are supposed to be enclosed in the electrical box. In this guide, we’ll look at the applications for each subtype of electrical box.
Standard rectangular box
Best for: Fixtures built into walls with individual switches or outlets.
The standard rectangular box, also known as a single gang box, is one of the most common types of electrical boxes. It is typically used to house a single switch or outlet. This is the versatile box you need if there’s nothing special about the installation.
Here are some details about the standard rectangular box:
It has a rectangular shape and is usually about 2 x 4 inches in size. This size fits all standard outlets and switches.
Standard boxes are available in both metal and plastic. Plastic is lighter and corrosion resistant. Metal is more durable and can act as a grounding conductor.
It can be used in new construction (installed on studs before drywall) or as an “old work” box installed on existing walls.
It can have built-in cable clips to secure NM-B cables.
Square box (4 inch square box)
Best for: Safely connect or bind multiple cords in one place.
The 4-inch square box is designed as a junction box, which means it is primarily used to connect (or “splice”) several electrical wires together. This allows the circuits to branch safely in different directions.
Compared with the rectangular box, this box saves more space. Because it’s larger than standard boxes, the 4-inch square box has enough room for multiple wires without crowding, making it ideal for handling complex wiring setups in commercial buildings and industrial sites. This metal box can be equipped with lids or clay rings to hold switches or outlets.
Appraiser box
Best for: Ceiling or wall mounts for small lighting fixtures or connection points with a maximum weight capacity of 50 lbs.
An octagon box is an electrical box shaped like eight sides, typically used in ceiling or wall installations. It is ideal for housing small light fixtures, smoke detectors, fan/light combinations or to act as a connection point where multiple electrical wires connect.
Octagon boxes are available in different depths and are usually made of metal, are sturdy and often feature multiple slots (pre-drilled holes) to accommodate wires from different directions. They provide ample space for wiring connections, especially in installations that require multiple cables or heavier installation.
Octagonal boxes are deeper than standard rectangular boxes, which means you can add more wire in there than necessary. If you need more space or a flexible option for wiring, this is the box for you.
Round pan tray
Best for: Lightweight ceiling fixtures, smoke detectors, or small crossovers weighing up to 6 lbs.
A round pan box is a shallow, circular box typically used for ceiling-mounted fixtures where space is limited, such as small light fixtures or smoke detectors. Their small size makes them ideal for areas that don’t require a deep box, such as surface-mounted lighting. Round boxes are often made of metal to provide stability and are usually bolted directly to ceiling joists for secure support. These boxes are typically 4 inches in diameter and about 1/2 to 3/4 inch deep.
Weatherproof box (external box)
Best for: External electrical installations to protect against environmental factors such as weather and humidity.
A weatherproof box is installed on exterior walls or roofs. They are used to install outlets and outdoor lighting. They are often classified as NEMA 3R or NEMA 4 Weather resistant thanks to tighter seals than regular boxes.
Weatherproof boxes are made of corrosion-resistant materials such as aluminum, stainless steel, or heavy-duty PVC. They also have rubber or foam gaskets around the openings and seams, ensuring a watertight seal.
Many weatherproof boxes come with mounting brackets and are mounted directly to exterior walls. It may also include knockouts of channel splices.
Outdoor boxes are commonly used in courtyards, garages, and gardens.
Ceiling fan box
Best for: Securely support ceiling fans and heavy lighting fixtures.
A ceiling fan box is typically rated to support up to 70 pounds for ceiling fans and about 90 pounds for fixed (non-moving) fixtures. Ceiling fans need their brand of electrical boxes because they are heavy and constantly moving.
Ceiling fan boxes are made of sturdy metal or reinforced plastic. Mounts directly to ceiling joists or other secure framing for stability. Ceiling fan boxes often include holes or threaded supports to securely hold the fan hardware, preventing wobbling or sagging over time. Unlike standard boxes, they are designed to withstand the vibration and movement of the fan blades.
They are usually round or octagonal, and designed to fit easily into ceiling fans or light fixtures. They are usually about 4 inches in diameter and vary in depth, usually between 1/2 inch and 2 inches.
New Labor Fund
Best for: New construction projects with open walls for direct screwing before drywall.
A new work box is an electrical box specifically designed for installation in new construction before walls are sealed. 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 mounting tabs, making it easy to attach firmly to the frame structure.
Because the new work box is installed before the drywall, you can plan the exact placement of cables without cutting them into the wall. This makes them great for new construction or remodeled apartments.
Old work box
Best for: Redesign or update projects with finished walls.
Old work box Designed to mount on existing walls without having to open them. It mounts directly into cut wall openings and is secured with side clips or “wings” that hold it in place. This makes them 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, such as switches or outlets, side by side. Popular in areas that need separate controls for lights or outlets. It is often used in living rooms or bedrooms with multi-layered lighting. Available in both metal and plastic, with options for new work or old work.
3- Gang box
Best for: It includes three switches or outlets in one place.
It’s designed to handle three devices, making it ideal for large rooms that have multiple lighting zones or switches for different fixtures.
4- Gang box
Best for: Accommodate four switches or outlets together in one place.
Designed for spaces that require four appliances in one place, they are often seen in high-use areas such as kitchens or entryways where multiple controls (lights, fans, outlets) are required. Usually made of stainless steel metal, plastic types are not common, as they are meant to have extra space for wires.
Nassau National Cable offers all types of electrical boxes, including Junction boxes, standard rectangular boxes, Square boxes, Octagon boxes, Round pan boxes, Weatherproof electrical boxes, Ceiling fan boxes, Old work boxeset al.