These requirements are echoed in NFPA 70-2017: National Electrical Code (NEC), Article 110. Both of these sections address the first reason to provide descriptive equipment labels: for personnel safety. formation and meet permanency of marking requirements. Compliance with permanency of marking requirements helps ensure that the labels will adhere to the. This standard describes requirements for numbering and labeling of real property electrical distribution equipment, circuits, and site lighting at Lawrence Livermore National Laboratory. This is an internal LLNL standard meant to guide the design of new facilities, facility modifications, and. Electrical insulation. Heating effects under conditions of use.