Plastic Electrical Box versus Metal Electrical Box

Which Electrical Box is Right for Your Residential Wiring Project

By Mark J. Donovan

When it comes to doing minor residential work a lot of do it yourselfers find themselves contemplating the plastic electrical box versus metal electrical box decision. The simple answer is that for most residential applications the plastic electrical box is the better choice. For one, a plastic electrical box is less expensive. Secondly, a plastic electrical box, unlike a metal electrical box, does not need to be grounded. Grounding an electrical box takes more time, and thus why most electrical contractors try to use non-metallic electrical boxes when they can.

This said, the metal electrical box has been around for decades, and was the only option until the advent of the non-metallic or plastic electrical box.

In addition, there are some applications where the metal electrical box is the required choice. For one, electrical metal boxes have traditionally been used and even required in commercial applications. See how to install an electrical box.

Second, they are also frequently used in outdoor applications. Metal electrical boxes are also required when the electrical box is to be buried behind an exterior wall as in possibly a junction box application.

Another advantage of plastic electrical boxes versus metal electrical boxes is the fact that plastic electrical boxes commonly have mounting nails integrated into them. This makes the installation of a plastic electrical box easier than a metal one. 

Here is an electric bux for a light.

Watch this video on how to install a pull chain light fixture.

In addition, the break-out tabs for inserting the Romex cables are usually easier to pop out than with metal electrical boxes, plus there is less risk of getting cut.

Though a plastic electrical box, versus a metal electrical box, does not need to be grounded itself, the ground wires associated with the various Romex cables coming into the box, along with the outlet or switch receptacle, need to be properly tied off together. Connecting the various ground wires together and tying them to the electrical outlet receptacle or switch prevents the risk of short circuits that could lead to fire and life threatening shock.

Learn what to do when no ground wire in an electrical box.

Make sure to always use the right grounding clamps when tying grounds together and fastening them to the electrical outlet receptacles and switches.

No matter the decision between a plastic electrical box and a metal electrical box, it is important to purchase electrical boxes that are rated for the particular number of Romex cables that are to be fed into it. If an electrical box is overstuffed with cables broken wires and short circuits could occur. All electrical boxes are marked with the rating capacity stenciled on the side of them. 

In addition, always make sure to buy electrical boxes that meet local and national electrical codes. If you still have questions on buying the right electrical box ask a store manager at the home improvement center for assistance.

For help on building a new custom home, see’s New Home Construction Bid Sheet. The New Home Construction Bid Sheet provides you with the knowledge on how to plan a custom home building project, and what to look for when hiring contractors for your new home construction. It also includes a detailed cost breakdown table and spreadsheet for estimating your own new home construction building costs.

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