Types of Biscuit Jacks

No discussion of wall plates would be complete without a discussion of biscuit jacks, or surface-mount jacks that look like small biscuits (see Figure 1). They were originally used in residential and light commercial installations for telephone applications. In fact, you may have some in your home if it was built before 1975. Biscuit jacks are still used when adding phone lines in residences, especially when people can't put a hole in the wall where they want the phone jack to go.

 
Figure 1: An example of a biscuit jack

Types of Biscuit Jacks

The many different types of biscuit jacks differ primarily by size and number of jacks they can support. The smaller type measures 2.25 inches wide by 2.5″ high and is mainly used for residential-telephone applications. The smaller size can generally support up to a maximum of two jacks.

The larger-sized biscuit jacks are sometimes referred to simply as surface-mount boxes because they don't have the shape of the smaller biscuit jacks. These surface-mount boxes are primarily used for data communications applications and come in a variety of sizes. They also can have any number or type of jacks and are generally modular. Figure 2 shows an example of a larger biscuit jack that is commonly used in surface-mount applications.

 
Figure 2: Example of a larger biscuit jack

Note

Generally speaking, the smaller biscuit jacks are not rated for Category 5e (or any higher categories). They must be specifically designed for a Category 5e application. Some companies offer a modular-design biscuit jack that lets you snap in high-performance, RJ-45-type jacks for Category 5e and better compliance.