What requirement is there regarding open knockouts in cabinets and panelboards?

Open knockouts in cabinets and panelboards must have a cover installed to ensure safety and compliance with electrical codes. Leaving knockouts open can expose electrical components to dust, moisture, and foreign objects, which can create hazards and affect the operation of the electrical system. The requirement for covers helps protect the wiring and connections inside the enclosure, prevents accidental contact with live parts, and maintains the integrity of the enclosure.

While it is important to consider that some options may address specific conditions, the correct requirement is to ensure that any open knockouts are securely covered to prevent these potential hazards. This is a key safety practice in electrical installations, promoting both functionality and adherence to regulatory standards.