This article covers the purpose of the Code, the scope and arrangement of the Code, enforcement, mandatory rules, permissive rules and explanatory material, the method of obtaining formal interpretations, examination of equipment for safety, wiring planning and units of measurement. It should be noted that Section 90.1 states that the National Electrical Code is not intended to be used as a design specification for untrained people. It contains provisions for safety. Compliance with the Code does not ensure that the installation is adequate for good service or that it is convenient or efficient. These criteria are left to other qualified personnel such as electrical engineers or designers.