Metal vs. Plastic: Which Material is Better for Your Electrical Box?

An electrical box is a vital component of every home's or building's electrical system. These enclosures house wiring connections of various applications like switches, outlets and fixtures, and transition wires, facilitating their easy access. Electrical boxes protect the cables and wires from any external damage, short circuit, and other issues that may hamper their functioning or cause electrical fires. 

While installing electrical boxes, homeowners, especially DIYers, should ensure that they use the correct type of box which satisfies the industry standards and the local building codes. It is always advisable to hire a professional electrician for electric box installation to get the job done right.

Metal and plastic are the most common materials used to construct electrical boxes. Metal boxes are primarily made from steel, aluminum, or cast iron, while non-metallic boxes use PVC or fiberglass. 

Is it beneficial to replace the metal electric box with plastic?

Metal boxes were the standard in the market before the advent of plastic electrical boxes. However, with the introduction of inexpensive and easy to work with plastic electrical boxes, several homeowners wonder whether they should replace their old metal electric boxes with plastic.

The advantages of plastic electrical boxes 

Plastic electrical boxes are great for residential applications. Besides the low cost, another benefit is that it does not require grounding, which is very time-consuming. Due to this, most DIYers and various electrical contractors use plastic electrical boxes when possible.  

Unlike metal boxes, a plastic electrical box does not conduct electricity when touched by a live wire, and these non-conductive boxes need not be grounded. The plastic electrical box is also lightweight and easier to install as they come with pre-integrated mounting nails or clamps. 

Homeowners can replace their metal electrical box with plastic if non-metallic cables come in and out of the box. 

However, the downside of plastic electrical boxes is that they distort or crack under stress, and PVC can melt due to overheating. Also, the nail brackets easily break off during installation or replacement, which will make it impossible to install them.

When are metal boxes the better choice?

Metal boxes are fireproof, strong, do not melt, warp, crack, crush, or bend, and provide excellent security for various electrical wiring applications. Local building codes in several places require using metal electrical boxes due to their durability, superior performance, and longer life. During installation, DIYers should wear gloves to avoid injuring themselves from the sharp edges.

It is mandatory to use a metal electrical box when a metal conduit or metal-sheathed cable runs in and out of the box. Another situation where it is better to choose a metal electrical box is for interior exposed applications, including conduits in unfinished basements and mudrooms with incomplete drywall systems. Though it is possible to use metal boxes with non-metallic wiring, it is essential to ensure proper grounding.

For outdoor installations, consider weatherproof electrical boxes made from aluminum to protect the wires from moisture damage. 

Get professional help to choose the correct electrical box 

Usually, the choice of metal or plastic electrical boxes is a matter of ease, budget, and personal preference. However, in a few cases, especially for grounding, the choice is clear. An electrician can inspect and suggest whether you should replace your existing metal electrical box with a plastic option.

If you need a highly-reviewed, licensed electrician in the Phoenix Valley area, call Efficient Electric at 623-900-1461. We would love to hear from you!