One of the most important NEC requirements (and yet one most often ignored) is 110.22: Identification of Disconnecting Means. It reads: “Each disconnecting means shall be legibly marked to indicate its purpose unless located and arranged so the purpose is evident.
Jim Dollard has an extensive background in codes and standards. If you have a query about the National Electrical Code (NEC), Jim will help you solve it. Questions can be sent to firstname.lastname@example.org. Answers are based on the 2014 NEC. Point of supply