Charles R. Miller

Code Contributor

Charles R. Miller, owner of Lighthouse Educational Services, teaches classes and seminars on the electrical industry. He is the author of “Illustrated Guide to the National Electrical Code” and NFPA’s “Electrical Reference.” He can be reached at 615.333.3336, or

Articles by Charles R. Miller

January 2010
Article 220 of the National Electrical Code (NEC) provides requirements for calculating branch-circuit, service and feeder loads. Definitions for the three types of loads that Article 220 covers are in Article 100. A branch circuit is the circuit conductor between the final overcurrent device protecting the circuit and the outlet(s). READ MORE
December 2009
The National Electrical Code (NEC) contains an introduction, nine chapters and eight annexes; Article 90 is the introduction to the NEC, and it includes specifications that are essential to the rest of the Code book. The scope is one item covered in the introduction (in 90.2). Most articles have a scope, but there is a difference between this article and all other articles. READ MORE
November 2009
The first edition of the National Electrical Code (NEC) was published in 1897 by the National Board of Fire Underwriters, which is now the American Insurance Association. Safety was the reason a group of 23 people met to develop a national set of rules for electrical construction and operation. In 1911, the National Fire Protection Association (NFPA) assumed sponsorship and control of the NEC. READ MORE
October 2009
The National Electrical Code (NEC) contains many provisions where calculations are involved. Understanding the purpose of these calculations, as well as how to perform them, is essential to individuals who are in the electrical industry. Passing a journeyman’s, master’s or electrical contractor’s exam may depend on a thorough knowledge of NEC calculations. READ MORE
September 2009
Provisions in article 220 are few in number compared to the total number of provisions in the National Electrical Code (NEC) book. The number of pages containing requirements in Article 220 makes up approximately 1½ percent of the total number of pages in the NEC that contain requirements. This small percentage is not proportional in size to the importance of this article. READ MORE
August 2009
As stated in the introduction, the purpose of the National Electrical Code (NEC) is the practical safeguarding of people and property from hazards arising from the use of electricity [90.1(A)]. Ensuring branch circuits, feeders and services are not undersized is one aspect of practical safeguarding. READ MORE