The NEC does not recognize NEMA 3R devices for indoor use because NEC paragraph 110.28 and Table 110.28 only acknowledge NEMA 3R devices for outdoor use. This is because NEMA 3R devices are designed to protect against outdoor conditions such as rain, snow, and dust, while indoor devices are not required to meet the same level of protection.However, some manufacturers, such as Schneider Electric, do list their NEMA 3R devices as being suitable for both indoor and outdoor use. This is because their devices meet the requirements of both the NEC and NEMA 3R standards. Ultimately, it is up to the user to decide whether or not to use a NEMA 3R device indoors. Flag for review