Electrical Exam Term
Knockout
A pre-scored, removable disc in an electrical box or enclosure that can be punched out to create an opening for conduit or cable entry.
Detailed Explanation
Knockouts come in standard trade sizes (1/2", 3/4", 1", etc.) and can be concentric (multiple sizes nested) or individual. All unused knockouts must remain intact to maintain the enclosure's rating and protection. When removed, an appropriate connector or fitting must be installed to secure the conduit or cable and maintain the enclosure's integrity. NEC 110.12(A) requires all unused openings to be effectively closed.
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Practice QuestionEasy
Which of the following best describes the concept of Knockout?
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