Metal Or Plastic Electrical Box – Know The Differences

As a homeowner or electrician, choosing between a metal or plastic electrical box can be a daunting task.

The biggest difference between metal and plastic electrical boxes is their durability and strength. Metal boxes are stronger and more durable, making them ideal for heavy-duty applications, while plastic boxes are more lightweight and flexible, making them an excellent choice for do-it-yourself projects or remodeling work.

If you’re unsure about which option is right for you, don’t worry.

In this article, we’ll take a closer look at the differences between metal and plastic electrical boxes and help you determine whether you should go for a metal or plastic electrical box.

Whether you’re a professional electrician or a DIY enthusiast, we’ve got you covered with all the information you need to choose the right type of electrical box for your project.

So, let’s dive in.

Comparison Factors Between Metal And Plastic Electrical Box

When it comes to selecting an electrical box, choosing between metal and plastic can be a challenging decision. Both have their advantages and disadvantages, and it’s important to consider various factors before making a final decision.

In this section, we will explore the comparison factors between metal and plastic electrical boxes to help you make an informed choice for your project.

Weight

Metal boxes are heavier than plastic boxes, making them more challenging to handle and install. Plastic boxes are lightweight, making them easier to handle and install.

Price

The cost of metal electrical boxes can vary widely depending on the size, shape, and features. Usually plastic boxes are typically less expensive than metal boxes.

A basic metal electrical box can cost around $1.50 to $10, while a more specialized or larger box can cost up to $50 or more.

Plastic electrical boxes are generally less expensive than metal boxes, with prices ranging from $0.50 to $5 or more, depending on the size, shape, and features.

Warranty

The warranty for electrical boxes can also vary widely, considering the manufacturer and type of box.

Metal electrical boxes often come with a longer warranty than plastic boxes due to their durability and longevity.

Warranties for metal electrical boxes can range from 1 year to a lifetime, depending on the manufacturer and specific product.

Plastic electrical boxes typically come with a shorter warranty, ranging from 90 days to 1 year, depending on the manufacturer and specific product.

Fire Rating

Fire ratings for electrical boxes are typically determined by Underwriters Laboratories (UL) in the United States and are expressed in terms of the number of hours the box can resist fire.

Metal electrical boxes are highly fire-resistant, which makes them a safer option in case of electrical fires. The metal construction also provides better impact resistance and can withstand more pressure than plastic boxes.

Plastic boxes, on the other hand, are less fire-resistant than metal boxes, which may be a concern in case of electrical fires. They also tend to be less sturdy and can break more easily under impact.

Installation

Metal electrical boxes are more challenging to install than plastic boxes due to their weight and the need for specialized tools.

They often require screws and bolts to attach to a wall or ceiling and may require a knockout tool to create holes for electrical wires.

Plastic boxes, on the other hand, are easy to install due to their lightweight and comfortable design.

They can often be attached using nails or screws and do not require any particular tools.

Corrosion Resistance

Metal electrical boxes are resistant to corrosion, making them a great option for outdoor or damp environments.

They can withstand exposure to water, humidity, and other environmental factors without rusting or degrading.

Plastic electrical boxes, on the other hand, are prone to corrosion, making them less suitable for outdoor or damp environments.

Exposure to moisture or UV light can cause plastic boxes to become brittle and prone to cracking or breaking.

Conductivity

Metal electrical boxes conduct electricity, which is essential for grounding and continuity.

They provide a consistent grounding source for electrical circuits and can help prevent electrical shocks and other hazards.

Plastic electrical boxes are non-conductive, which means they cannot conduct electricity and are unsuitable for grounding.

This can be a crisis in applications where grounding is essential, such as in high-voltage electrical systems.

Availability

Metal electrical boxes are less widely available than plastic boxes, which may limit the options for certain projects.

They may also be more expensive due to their higher cost and specialized construction.

Plastic electrical boxes are widely available and come in various sizes and shapes, making them versatile options for different projects.

They are also more affordable than metal boxes, making them a popular choice for budget-conscious projects.

When Should You Go For Metal Electrical Box

Metal boxes can be a little more difficult to work with than plastic boxes. Metal boxes require supplementary clamps, and their sharp edges can chafe hands.

Also, attaching the bare or green grounding wire to the metal electrical box using a screw allows for the use of Romex or NM wiring, but it’s important to take special precautions to ensure proper grounding.

Here are some situations where metal electrical boxes are highly recommended or required:

• When metal-sheathed cable (armored BX cable) or metal conduit is running in or out of the box as metal cable and conduit require contact from its metal sheathing to the metal box to complete grounding.

• When you need to attach the electrical box directly to a masonry wall in interior exposed applications such as unfinished basements and mudrooms where the wires are also exposed.

• When mounting heavy items such as ceiling fans.

• When attachment to the stud is a major concern, metal boxes provide a strong attachment to the stud, and you can drive strong screws into the studs to ensure maximum holding power.

• When you need an ultra-strong, fireproof, and capable-of-being-melted electrical box that offers the greatest level of security for all electrical wiring applications.

When Should You Go For Plastic Electrical Box

Plastic electrical boxes are considerably lighter than metal boxes, making them easier to handle and install.

Also, the holes in plastic boxes are easy to punch out in the back or sides. This makes it simple to install electrical components and adjust the wiring.

• Although not mandated by the electrical code, it is recommended to use plastic electrical boxes when Romex (or NM) cables are entering or exiting the box.

• Plastic boxes are ideal for applications that can be grounded through other measures since they cannot provide grounding on their own.

• Plastic boxes are a good option for DIY home remodelers since they are lightweight, easy to work with, and less expensive than metal boxes.

• Plastic boxes come with built-in clamps for the wires, eliminating the need for additional clamps.

• If you are retrofitting an existing space or working on a remodeling project, plastic electrical boxes are often the best choice. Old work or remodel boxes have wings that allow them to be attached directly to drywall, making them ideal when there is no unrestricted access to a stud.

• Plastic boxes are available in different types, such as pre-attached nail boxes, remodel boxes, and boxes with adjustable metal brackets that offer more flexibility.

However, plastic boxes can twist out of shape, and their doors may not always hold cables firmly. They can also melt in case of fire.

Signs That Your Electrical Box Needs Replacement

Your home’s electrical system is crucial to your safety and comfort, and the electrical box is a critical component that protects your home from electrical hazards.

In this section, we’ll discuss some signs that your electrical box needs replacement, whether it’s made of metal or plastic.

Metal Electrical Box

Rust and Corrosion

One of the most common signs that your metal electrical box needs replacement is the presence of rust or corrosion.

Over time, exposure to moisture and humidity can cause the metal to deteriorate, leading to rust and corrosion.

These can weaken the structure of the box, making it less useful at protecting your home from electrical hazards.

If you notice rust or corrosion on your electrical box, it’s important to have it inspected by a professional electrician, who can determine whether it needs to be replaced.

Damaged or Missing Knockouts

Knockouts are the holes in the electrical box that allow wires to enter and exit. Over time, these knockouts can become damaged or knocked out, which can compromise the integrity of the box.

If you notice that knockouts are missing or damaged, it’s important to have them replaced as soon as possible to prevent electrical hazards.

Overcrowding

Another sign that your metal electrical box needs replacement is overcrowding. Over time, you may add new circuits or electrical devices to your home, which can result in overcrowding of the electrical box.

This can create a dangerous situation, as the box may become overheated or overloaded.

If you notice that your electrical box is overcrowded, it’s important to have a professional electrician inspect it to determine whether it needs to be replaced.

Outdated Technology

If your electrical box is obsolete, it may not be equipped to handle the electrical demands of modern technology.

This can result in power surges, blown fuses, and other electrical hazards.

If your electrical box is outdated, it must be replaced with a newer, more efficient model that can handle the demands of your home’s electrical system.

Plastic Electrical Box

Poor Connections

Another sign that your plastic electrical box needs replacement is poor connections.

Over time, the connections between wires and the box can become loose or damaged, compromising the safety of your electrical system.

If you notice poor connections in your plastic electrical box, it’s important to have them inspected by a professional electrician, who can determine whether the box needs to be replaced.

Fading or Discoloration

Over time, plastic electrical boxes can fade or become discolored due to exposure to sunlight or other environmental factors.

While this may not necessarily indicate a safety concern, it can be a sign that your plastic electrical box is getting old and may need to be replaced soon.

Warping

Plastic electrical boxes can warp if they are exposed to high temperatures or if they are installed improperly.

Warping can compromise the integrity of the box and make it less effective at protecting your home from electrical hazards.

Water Damage

If your plastic electrical box is located in a damp or humid area, it may be susceptible to water damage.

Water damage can corrode the electrical connections inside the box and create a potential safety hazard.

Burning or Melting

If your plastic electrical box is exposed to high temperatures or is overloaded, it may start to burn or melt. This can create a fire hazard and should be addressed immediately.

Additional Maintenance Tips For Outdoor Metal Electrical Box

If you have an outdoor metal electrical box, it’s important to take extra care to maintain it, as it is constantly exposed to the elements. Here are some additional maintenance tips for outdoor metal electrical boxes:

Keep it Clean

Dirt, debris, and other outdoor elements can accumulate on your metal electrical box, which can compromise its effectiveness and safety.

Make sure to clean your box regularly using a soft cloth or brush to remove any debris or buildup.

Check for Rust

Over time, metal electrical boxes can rust, especially if they are exposed to moisture or humidity.

Check your box regularly for any signs of rust; if you notice any, use a wire brush or sandpaper to remove it.

You can also apply a rust inhibitor or protective coating to prevent future rusting.

Inspect the Seals

Outdoor metal electrical boxes have seals that help keep water and other elements out.

Inspect the seals regularly to make sure they are intact and not damaged. If you notice any damage, replace the seals immediately to prevent water damage.

Keep it Dry

Moisture is one of the biggest enemies of outdoor metal electrical boxes.

Ensure your box is installed in a dry, protected area, and avoid installing it in areas prone to flooding or pooling water.

Schedule Regular Maintenance

It’s a good idea to have a professional electrician inspect your outdoor metal electrical box at least once a year to ensure that it is functioning properly and to identify any potential issues before they become major problems.

By following these additional maintenance tips, you can help ensure that your outdoor metal electrical box is functioning properly and safely and that your home is protected from electrical hazards.

Final Verdict

In conclusion, choosing between a metal or plastic electrical box largely depends on your specific needs and preferences.

While metal boxes are typically more durable and fire-resistant, plastic boxes are often more lightweight and easier to install.

Regardless of the material you choose, it’s important to keep an eye out for signs that your electrical box needs replacement and to take proactive steps to maintain it.

By doing so, you can help ensure the safety and reliability of your home’s electrical system for years to come.

FAQ

Are metal or plastic electrical boxes better?

The answer to this question largely depends on your specific needs and preferences. Metal electrical boxes are typically more durable and fire-resistant, making them a good choice for high-traffic areas or areas prone to damage.

However, plastic electrical boxes are often more lightweight and easier to install, which can make them a better option for DIY projects or areas where weight is a concern.

Can plastic electrical boxes be used outdoors?

Yes, plastic electrical boxes can be used outdoors as long as they are rated for outdoor use and are installed properly.

It’s important to choose a plastic electrical box that is designed for outdoor use and to ensure that it is installed in a dry, protected area.

Are metal electrical boxes more expensive than plastic electrical boxes?

Generally speaking, metal electrical boxes are more expensive than plastic electrical boxes.

However, the cost difference is usually minimal and is often outweighed by the increased durability and safety features of metal boxes.

Can you use metal and plastic electrical boxes in the same circuit?

Yes, it is possible to use both metal and plastic electrical boxes in the same circuit. However, it’s important to ensure that the boxes are rated for the same voltage and that they are properly grounded.