Why are missing knockouts on electrical panels and junction boxes not allowed?

Missing knockouts on electrical panels and junction boxes are not allowed primarily because they may expose energized components, posing a shock hazard. Knockouts are designed openings in the boxes that allow for the entry of wires. When these knockouts are missing, there’s a direct path to live electrical parts, increasing the risk of accidental contact. This can lead to serious injuries, including electric shock, if someone were to reach into the panel or box while it is energized.

Additionally, keeping knockouts intact helps ensure that the electrical system is securely housed and minimizes potential exposure to the elements or foreign materials, which could cause further safety hazards. The integrity of electrical panels and junction boxes is critical for safe operation and compliance with electrical codes.