NEMA 3R enclosures can be used indoors.

NEMA 3R enclosures are designed for outdoor use, providing protection against rain, sleet, and snow while being vented to allow for airflow. However, they can also be utilized indoors because they offer durability and weather resistance. Using them indoors may be beneficial in areas where moisture or dust could be a concern, or where there is a risk of incidental splashing. This versatility makes NEMA 3R enclosures suitable for both indoor and outdoor applications, thus supporting the statement that they can be used indoors.