Residential Electrical Boxes for DIY Home Improvement Projects

Electrical boxes are an essential component of almost every project involving electricity. The National Electrical code specifies that all splices and connections between wires must occur in a box that passes the code requirements, making it particularly important that you know which one is right for the job.

Most do it yourself homeowners will replace broken equipment with a newer model. However, with different materials and sizes available, you can often find an electrical box that will meet your specific needs better than the standard issue model. Here’s a rundown of the typical options you’ll find at a home improvement store and which are appropriate, or not appropriate, for a specific project.

Rectangle boxes

These rectangle electrical boxes are the most common in residential construction. These often contain a single light switch or a single pair of electrical outlets. Sometimes these have a detachable side that can be attached to another box to make it twice as wide.

Square boxes

A square electrical box will be 4″x4″ and is predominantly used for splicing cables and a double pair of electrical outlets or a single pair of light switches. If you find a square electrical model in a place where you need a rectangle, don’t bother replacing it: there are adapter covers that will make it function like a rectangle electrical box.

Braced octagonal boxes

A braced octagonal electrical box is made to be attached between ceiling joists. It has two adjustable braces that are attached to the joists on either side of the electrical box. These are used when centering a light fixture is essential but there are no nearby joists. Keep in mind that it is always preferable to attach directly to a joist if possible.

Outdoor boxes

An outdoor box has sealed seams and a foam gasket to prevent the elements from infiltrating the box and shorting the circuit. For this reason an outdoor residential model is essential for any exterior electrical job. Outdoor options will also hold up better than standard rectangles; they have a corrosion resistant coating that protects them from the weather.

Fiberglass boxes

Fiberglass boxes are still so new in the residential construction industry that different local codes have different rules regarding their use. Their greatest allure is their cost when compared to traditional options, although some are rated to withstand fire better than metal. If you are considering using this option, research the codes and manufacturer’s involved thoroughly before use.

Plastic boxes

These are only found in new residential construction and cannot be used for metallic cables. You may also have to install a grounding screw to use them and pass code. Some local codes prohibit their use and the only real advantage to using them is the cost savings involved. However, the amount of money saved when doing a small project is minimal when compared to the risks and other hassles of using plastic. For this reason, avoid using them when working with electricity.