Final answer:
The NEC Article that specifies the percentage fill of fixture wires in a conduit or tubing is NEC Article 314. It contains essential guidelines for the safe installation of electrical wiring.
Step-by-step explanation:
The number of fixture wires in a single conduit or tubing is governed by the requirements specified in the National Electrical Code (NEC). The correct reference for determining the maximum percentage fill of conduit or tubing is found in NEC Article 314. According to NEC Article 314, the fill requirements are crucial to ensure the safe installation of electrical wiring by preventing overheating and allowing for future maintenance.
It's important to adhere to these codes to maintain electrical safety and prevent hazards such as fires or electrical faults. The NEC provides tables and guidelines to determine the correct conduit size and the maximum number of wires it can contain based on the sizes of the wires being used.