Given the title of this article, you might expect the citations to all be in Art. 430. But we begin with Art. 110.
Poor workmanship [110.12] is often a factor in motor failures. For example, an electrician troubleshooting a “failed” motor found the cause inside the weatherhead. The wires had been twisted together by hand and then wrapped in tape. That unreliable assembly method is a failure waiting to happen, and, in this case, it occurred.