An Ultimate Guide for Metal Distribution Boxes

Distribution boxes are an essential part of every home or building’s electrical system. These enclosures house wiring connections for various applications such as switches, receptacles, and fixtures as well as transition wires for easy access. Distribution boxes protect cables and wires from any external damage, short circuits, and other issues that could hamper their functionality or cause electrical fires.

When installing a distribution box, homeowners, especially DIY enthusiasts, should ensure that the correct type of distribution box is used that complies with industry standards and local building codes. To ensure the job is completed successfully, we always recommend hiring a professional electrician for distribution box installation.

The materials and construction of a distribution box are critical in determining its safety features and the overall effectiveness of the protection system. First, the choice of material directly affects the ability of the distribution box to provide a safe enclosure for electrical connections. Metal and plastic are the most common materials used to manufacture electrical boxes. Metal boxes are primarily made of steel, aluminum, or cast iron, while non-metal boxes use PVC or fiberglass.

1. Types of electrical distribution boxes

Regardless of the classification criteria based on materials or usage scenarios, there are many types of distribution boxes, each with a specific purpose. The following will introduce several very common categories:

1). Metal distribution box

Metal makes these distribution boxes strong and durable. The strength of metal provides these distribution boxes with multiple functions. Such as fire and mechanical damage. Even plastic containers cannot withstand damage in such extremely adverse environments. They are often used in industrial environments. They are perfect for protecting electrical connections in harsh environments.

2). Plastic distribution box

Plastic distribution boxes are common in residential and commercial settings. They are lightweight, easy to install, and non-conductive, making them safe to use in a variety of situations. Known for their lightweight, these distribution boxes are commonly found in different industries. They are also found in large quantities in residential and commercial areas, where we use them to protect premises and wiring connections from risks and damage.

Plastic distribution boxes are non-conductive and will not let the current pass through. This feature makes them very reliable in residential and commercial applications. Apart from this, they are also corrosion-resistant. This means that in a humid environment, they can easily bear the risk of corrosion.

3). Weatherproof distribution box

Ideal for outdoor applications, weatherproof distribution boxes are built to withstand the elements, ensuring electrical connections remain secure even in harsh conditions.

4). Underground distribution box

They are buried underground to protect electrical connections in outdoor landscaping, such as garden lighting or underground wiring.

2. The importance of metal boxes

Whether it’s a residential, commercial or industrial space, electrical distribution boxes play a vital role in electrical systems by encapsulating electrical connections and protecting them from damage or interference.Metal boxes are usually made of steel or aluminum and have been widely used in electrical installations for many years. Some of the advantages of metal boxes are as follows:

Durability: Metal boxes are known for their ruggedness and durability, making them ideal for demanding environments or areas prone to physical shock.
Fire Resistance: Metals are inherently fire resistant, providing an extra layer of safety in the event of an electrical fault or short circuit.
Electrical Grounding: Metal boxes can be effectively grounded, providing protection against electrical shock and reducing the risk of electrical fires.

Here are some disadvantages of metal boxes:

Conductivity: While metal boxes have the advantage of being grounded, they also conduct electricity. If not properly installed, they can accidentally contact live wires or cause a short circuit.
Weight and installation difficulty: Metal boxes tend to be heavier than plastic boxes, making them more challenging to install, especially in retrofit applications.
Corrosion: In wet or corrosive environments, metal boxes may be susceptible to rust or corrosion over time. Regular maintenance and proper sealing are required to prevent damage.

If sparks occur due to a loose connection or short circuit, the distribution box can also prevent the spark from igniting combustible materials. Some distribution boxes act as a grounding point, allowing fault current to flow safely away. This prevents electrical faults and ensures that the system is properly grounded.

Although many people may think that plastic boxes are better and more affordable than metal distribution boxes, this is not true. Plastic boxes are highly durable, fireproof, and have grounding and shielding capabilities compared to metal boxes. Although plastic boxes may have some advantages, such as being cheaper and lighter than metal boxes, their disadvantages outweigh the advantages. Plastic boxes do not conduct electricity and, in some cases, do not offer the same resilience as metal boxes. In addition, if the plastic box is not of the best quality, it has a high chance of burning and melting in the event of a short circuit, thus easily resulting in a short lifespan for the plastic box. This is also why metal boxes, despite their higher cost, are a better choice.

Therefore, for the above situation, a metal distribution box seems to be a better choice.

3. How to choose a metal distribution box

After determining that a metal box is needed based on the usage scenario, we can determine the most basic performance, structure and other requirements from the following aspects.

1). For metal distribution boxes, you need to know the exact size required for your specific application to ensure that the wires are properly installed and organized. The total volume of the box is the free space for the wires and wiring devices to be installed. The volume of the distribution box is measured in cubic inches, and the volume of the distribution box must be equal to or greater than the total volume of the contents. Add up the total volume of all the wires, connectors, and devices (outlets, switches, dimmers, etc.) that you will install in the distribution box to determine how large a distribution box you need.

2). When considering buying a metal electrical distribution box, it is vital to understand its level of weatherproofing against heat, water, and dust. Such distribution boxes usually have an IP rating that indicates their effectiveness against elements such as dust and water. The cover of the distribution box should fit tightly against the body to prevent any water penetration when mounted on a wall or surface. Check for materials that meet the UL 94 rating to achieve a V-0 rating for the best fire resistance.

3). Grey distribution boxes are common as they blend in easily with the environment, while the transparent covers facilitate visual inspection. Always contact the supplier to check if they have the specific size and type you require, and ask if the distribution box comes with all the necessary accessories to ensure a safe and secure installation to prevent power tripping.

4). The setback of a distribution box determines how far the face of the box is from the wall. This is important if you are using tile or other thick wall coverings. Use adjustable depth distribution boxes to ensure the correct setback. The number of gangs on a distribution box refers to how wide the box is and how many devices (such as outlets, switches, and dimmers) can fit in the box. A single-gang, or single-gang, distribution box is wide enough to hold one device (such as a switch or outlet).

5). The cable entry is where the cables enter the distribution box. It needs to be secure to protect the wires inside from dust, water, and damage.

Cable glands secure and seal the cables entering the distribution box, preventing dust and water from entering and protecting the cables from strain. Plastic, metal, and brass are widely used depending on the application.
Most cable glands on the market today are IP65 and IP67. In practice, most IP67 cable glands will fail an IP67 test. We recommend checking before finalizing IP67 requirements.
2-way, 4-way, 6-way, and 8-way, are common names for the number of entries into a distribution box. Select according to the layout direction or the cable entry position. We mainly recommend using the bottom cable entry only in exterior applications. In the case of the top or side entry, rainwater may enter the housing through the cable.

In addition to the above main considerations, we also need to refer to the following when purchasing:

Modular flexibility: The flexible structure allows customers to customize the interior to their specific needs. This versatility allows for efficient storage and organization of everything from tools to equipment.
Durability: Modular boxes should be of high quality, providing excellent durability and long-lasting performance even in harsh conditions. Distribution boxes from leading brands are made of high-quality materials that are resistant to moisture, corrosion, and impact. Therefore, they are suitable for use even in the most difficult situations. The powder-coated finish provides an extra layer of protection to the boxes, improving their resistance to scratches, impacts, abrasions, etc. This coating not only increases their durability but also makes them look more professional.
Convenient line connection: A distribution box allows you to connect cables in a convenient manner. This can simplify the wiring process and make troubleshooting electrical problems easier.

4. How to install a metal distribution box

Correct installation is essential to ensure the effective use of metal distribution boxes. Please strictly follow the following suggestions when DIYing:

Location: Place distribution boxes in strategic locations where electrical connections are required, ensuring easy maintenance.
Wiring: When connecting wires inside the distribution box, follow electrical codes and guidelines to ensure safe and secure connections.
Sealing: Seal the box properly to prevent moisture or dust from seeping in, which could cause short circuits or corrosion.
Size: Choose an appropriately sized distribution box to accommodate all of the wires and connections without overcrowding them.

During the installation process, DIYers should wear gloves to avoid being injured by sharp edges. Of course, to be on the safe side, we still recommend that you hire a qualified professional electrician to handle electrical problems.

5. Safety measures for metal distribution boxes

When working with electrical systems, remember that your personal safety is always your top priority:

Turn off the power: Before working on the electrical distribution box, turn off the power to prevent electric shock.
Periodic Inspection: Regularly inspect the terminal box for signs of wear, damage, or loose connections.
Use Proper Tools: Use insulated tools and safety gear when working on the distribution box.
Professional Help: If you are unsure about any aspect of working with an electrical distribution box, it is best to consult a licensed electrician.

6. Conclusion

Using the right distribution box can prevent electric shock and fire, ensure safety, keep wires organized, and increase the durability of the electrical system. In general, the choice of metal or plastic distribution box depends on convenience, budget, and personal preference. However, in a few cases, especially when it comes to grounding, metal distribution boxes are undoubtedly the wisest choice. If necessary, consult a professional electrician to ensure compliance and safety.