When a conduit passes through an exterior wall, what is required according to the NEC®?

When a conduit passes through an exterior wall, it is necessary to ensure that the installation is protected from environmental conditions such as moisture, pests, and temperature changes. According to the National Electrical Code (NEC), appropriate measures must be taken to seal or plug the points where conduits penetrate exterior walls.

The correct response emphasizes that seals or plugs are a requirement to maintain the integrity of the electrical system and to prevent unwanted intrusion of air, water, or other elements that could affect the functioning of the electrical system. Using both seals and plugs ensures that the conduit is properly protected against these external factors.

Choosing only plugs, as suggested in one of the options, would not fulfill the requirement to adequately seal the penetration, potentially leading to issues over time. Therefore, the emphasis on using either seals or plugs reflects the NEC's stance on maintaining safety and longevity in electrical installations.