You can increase the total volume of a box by adding a mud ring that is____.

• A. Marked with its volume
• B. Painted with its color
• C. Made of metal only
• D. Attached with screws

Answer: (A)

When you add a mud ring, the total inside space of the box increases by the amount of volume the ring adds. The only way to know exactly how much extra space you gain is if the mud ring is marked with its volume, so you can add that number to the box’s existing capacity to stay within code. The other options don’t relate to space: color, or being metal, don’t change how much interior volume the ring provides, and screws don’t add usable volume for conductors and devices.