Print Page   |   Contact Us   |   Sign In   |   Join
March-April 2002
Share |

March-April 2002 CoverMarch-April 2002

TABLE OF CONTENTS

Stories are available to subscribers or members only. Join now

[Stories marked with a * may be viewed by nonmembers.]

 

 

 

 

 

Features

Overcurrent Protection and the NEC

by George Gregory

The fundamental purpose of overcurrent protection is to protect conductors and equipment against the effects of excessive temperature on conductors and conductor insulation from overcurrent. Read more

Wiring Methods and Overcurrent Protection

by Robert McCullough

One of the most fundamental elements of an electrical installation is the connecting of the wiring method to an overcurrent device. Seems simple right? All most people seem to do (including inspectors) is to look at Table 310.16 and match up the numbers to a fuse or breaker. Unfortunately the actual selection process can be much more complicated than that. Read more

Selection of Arc-Fault Circuit Interrupters

by Steve Campolo

The 2002 National Electrical Code (NEC) requires that the branch circuits supplying outlets of dwelling unit bedrooms, as well as mobile homes and manufactured home bedrooms, be protected by arc-fault circuit interrupters (AFCIs). Rules 210.12 and 550.25 are clear in this requirement. However there is considerable confusion as to which type of AFCI meets the intent of the Code. Read more

Circuit Overcurrent Protection

by Clive Kimblin

Overcurrent devices protect the circuit conductors and conductor insulation from overheating. They also limit the damage associated with overheating and faults in downstream equipment. Fuses performed this function during the first days of electrical distribution, but circuit breakers of ever increasing sophistication have been available since the early 1900s. This paper focuses on circuit breakers and describes the wide variety of available devices. The emphasis is on low-voltage residential, industrial and commercial applications where the circuit voltages range from 120 volts through 600 volts. This is the area that is commonly encountered by electrical inspectors. Read more

Grounding Separately Derived Systems

by Michael Johnston

Grounding separately derived systems is required where the system meets the characteristics of 250.20. This section gives the conditions under which electrical systems are required to be grounded. A system that is grounded has one conductor of the system intentionally grounded. Whether the system is required to be grounded or is grounded by choice, it must follow all the requirements for grounding separately derived systems as covered in 250.30. Read more

Feeder and Transformer Secondary Tap Conductors

by Jim Dollard

Applying the rules of the 2002 NEC for tap conductors is a topic that has generated many interesting code discussions on jobsites as well as at inspector meetings. The discussion and application of the tap rules in the NEC must begin with the conductor in question. Read more

Selection of Arc-Fault Circuit Interrupters

by Daniel R. Neeser

The 2002 National Electrical Code (NEC) requires that the branch circuits supplying outlets of dwelling unit bedrooms, as well as mobile homes and manufactured home bedrooms, be protected by arc-fault circuit interrupters (AFCIs). Rules 210.12 and 550.25 are clear in this requirement. However there is considerable confusion as to which type of AFCI meets the intent of the Code. Read more


Temporary Installations

by Richard Owen

The first thing one notices about Article 305, Temporary Wiring, in the 2002 National Electrical Code is that it is no longer there! By direction of the Technical Correlating Committee, Article 305 has been relocated to Chapter 5 and re-identified as Article 527. Read more

Departments

Editorial

Another Step Forward

by Philip Cox

The electronic age has opened the way to an exciting world involving advanced methods of communications. What was once thought to be science fiction or unrealistic dreams is now reality. The feverish pace being experienced in the electronic or informational technology industry is difficult for many to understand well, much less to become skilled in its use. Improvements in computer hardware and software are constantly being made and users are at the mercy of those changes. By the time a new computer is purchased and put into use, it is likely that a newer and more advanced model is already being produced. Read more

Canadian Code

Parallel Generation

by Leslie Stoch

The Canadian Electrical Code, Rule 14-612 Transfer Equipment for Standby Power Systems prohibits the simultaneous connection of two or more power supplies to electrical equipment and facilities. There is an obvious exception. Rule 14-612 does not apply to parallel generation systems covered by Section 84 — Interconnection of Electrical Power Production Sources. Section 84 does apply when an electrical utility customer opts to connect and operate its own generation equipment in parallel with the electrical utility network. Read more

UL Question Corner

Can Power Strips be Daisy Chained or Plugged Directly into a Wall Receptacle?

by Underwriters Laboratories

GTO cable is Listed by UL under the product category, Gas Tube Sign and Ignition Cable (ZJQX). Listing information for GTO cable can be found on the UL Online Certification Directory at www.ul.com/database, or on page 119 of the 2001 print edition of the General Information for Electrical Equipment Directory (White Book). There currently are no stand-alone GTO cables that are UL Listed under ZJQX that do not need to be installed in a raceway. Read more

Other Code

The 2002 NESC Strength and Loading $$

by David Young

The most significant change to the 2002 National Electrical Safety Code (NESC) is in the strength and loading requirements for aerial electric distribution and transmission facilities. Supporting structures and their supported facilities shall be designed to withstand extreme wind loading and a combination of ice and wind loading. Read more


Recent Issues

January-February 2002November-December 2001September-October 2001July-August 2001May-June 2001

By Issue Date:
 
By Section