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.
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.
In section 250.52(A)(2) of the 2005 and the 2008 editions of the National Electrical Code (NEC), the metal frame of a building or structure is considered to be a grounding electrode if the metal frame is connected to earth by one of four different methods.
A group of apprentices asked if there is an easy way to locate equipment and wiring method requirements in the Na-tional Electrical Code (NEC). If indeed there is a procedure, they wanted me to demonstrate such by designing and installing a motor system with examples.
Article 110 Requirements for Electrical Installations; Article 210 Branch Circuits; Article 230 Services; Article 250 Grounding and Bonding; Article 310 Conductors for General Wiring; Article 338 Service Entrance Cable: Types SE and USE; Article 680 Swimming Pools, Fountains, and Similar Installatio
Recently, I fielded a question about the basic statement in Section 695.3 of the 2008 National Electrical Code (NEC) that “electric motor-driven fire pumps shall have a reliable source of power.” The question involved the reliability of the power source for one of the most important electrical motor
I conduct a number of National Electrical Code (NEC)-related seminars each month. Lately, people have been asking about the requirements for grounding and bonding systems together to provide an equipotential plane.
Article 110 Requirements for Electrical Installations; Article 210 Branch Circuits; Article 240 Overcurrent Protection; Article 250 Grounding and Bonding; Article 310 Conductors for General Wiring; Article 410 Luminaires (Lighting Fixtures), Lampholders, and Lamps; Article 424 Fixed Electric Space H
When inspecting a small office facility for a customer, I was surprised that he had a fuel cell system for his main power source that was backed up by an optional standby generator system. In other words, the complex did not depend on utility power.
While preparing a presentation, I noticed a photo taken at a facility where temporary power was needed periodically. The facility rented a generator when necessary. It showed a disconnecting means with four individual conductors stubbed out of the bottom of the enclosure.