What are listed or labeled boxes?

Boxes that have been tested and certified by a recognized testing laboratory are referred to as listed or labeled boxes. This designation indicates that these boxes meet specific safety and performance standards set by the National Electrical Code (NEC) and other applicable standards. The certification process involves rigorous testing to ensure that the boxes can safely contain electrical connections and withstand various environmental conditions.

Listed or labeled boxes provide assurance to electricians, inspectors, and consumers that the products used in electrical installations have undergone third-party verification for quality and safety. This is crucial, as improper or untested materials can lead to electrical failures, fires, or other hazardous situations.

In contrast, boxes made from recycled materials may not undergo the same level of scrutiny, and custom-made boxes don't necessarily meet standardized testing unless they also obtain certification. Similarly, simply being labeled by the manufacturer does not guarantee that the box has been independently tested and verified for compliance with the relevant electrical safety standards. Thus, the significance of listed or labeled boxes lies in the assurance of their reliability and safety through recognized testing protocols.