Introduction

The National Electrical Code (NEC), produced by the National Fire Protection Association (NFPA), is known as NFPA-70 and is the "bible" of electrical design and construction. It is developed and written by a committee of some of the best electrical professionals who are knowledgeable in the safe and effective design, construction, operation, and maintenance of electrical systems, with input from the industry at large. It sets forth the minimum standards by which electrical systems should be designed and constructed.

While complying with the NEC minimum requirements will ensure safe and effective electrical system design and operation, good design practice often dictates that more stringent requirements be met, or more stringent requirements may be mandated by the local electrical inspector. Keep in mind that the authority having final jurisdiction for acceptance of an electrical system's design and installation is the local electrical inspector for the project. It may be prudent, therefore, to involve the local electrical inspector in the early stages of design and from time to time throughout the design process in order to help him or her become familiar with the project and your design intent and to see if there are any special requirements or possible differences in interpretation of the NEC, and thus to facilitate a design that will not only be safe and effective, but will be accepted with no costly surprises once in construction.

Interpretations of the NEC can be obtained from the NFPA both formally and...