Print Page   |   Contact Us   |   Sign In   |   Join
Juy-August 2010
Share |

July-August 2010 CoverJuly/August 2010


Stories are available to subscribers or members only. Join now. [Stories marked with a * may be viewed by nonmembers.]







Selective Coordination Enforcement: Overcurrent Protective Device Basics

by Tim Crnko

Merely having a higher ampere overcurrent protective device (OCPD) feeding a lower ampere overcurrent protective device does not assure a circuit is selectively coordinated. Designing a selectively coordinated system takes a knowledgeable person who is capable at the task and who has the necessary data available to select the proper devices. As an authority having jurisdiction (AHJ), evaluating whether a system is selectively coordinated does not require as much knowledge or work. However, it does require specific information which can be reviewed and interpreted. The specific information that must be provided for evaluation purposes depends on the method used to achieve selective coordination. This article covers the basics of selective coordination interpretation for fuse or circuit breaker circuits used in 600 V or less systems. Read more

Perspectives on PV

Odds and Ends

by John Wiles

In the course of daily business, I get some questions repeated many times. I try to address these areas of common and frequent interest in this series of articles, but there are always a few that need clarification or repeating. Read more

Mechanical Answer to Stray Voltage

by Adam Wilwerth

"Green" building... Tenants of the Time & Life Building in New York’s Rockefeller Center include Time Inc., publisher of more than 100 magazines. In an effort to "green” the building, shaft grounding rings have been installed to protect the bearings of HVAC fan motors. Read more

Air Conditioning… An Idea That’s Not as New As We Think!

by Jonathan Cadd

Air conditioning is a twentieth century phenomenon. The Romans had aqueducts. The British discovered electricity. The Americans had an engineer whose invention to control temperature and humidity changed the world forever — welcome to the air conditioner. Read more

The Difference between Success and Failure — How a Torque Wrench Improves System Reliability

by Christel Hunter

In NASCAR, pit crew members use impact wrenches with preset torque values to install lug nuts during a wheel change. A loose lug nut can mean the difference between winning and losing, as Greg Biffle found out in 2005 when loose lug nuts on the left rear tire caused vibration and forced him to take an extra pit stop at the Texas Motor Speedway. Biffle lost a lap and finished 20th, which cost him enough points to lose the Chase for the Nextel Cup to Tony Stewart. No race car driver or their pit crew would question the importance of using the proper tool and the proper torque on lug nuts. Yet many electricians go to work every day and tighten electrical connections with no more than a folding Allen set. Read more



Answers and Section Meetings

by Kathryn Ingley

In the fall of each year, IAEI members gather in each of the six sections to celebrate and to share the answers they’ve discovered. One of my fondest memories is my first visit to a code breakfast — at the Eastern Section, I think. The room was packed, plates were loaded with scrambled eggs, sausage and bacon, and hot breads; but, forgetting the hot food, men were lined up at twin microphones adamantly presenting their understanding of a code change. The panelists fielded the responses, asked insightful questions and led the participants to the official interpretations — only to be challenged from the floor. Too quickly, the final buzzer sounded; the time clock had run out. I looked down and realized I hadn’t eaten a bite. Read more

Canadian Code

Rule 10-812 — Grounding Conductor Size

by Leslie Stoch

Rule 10-812 specifies minimum grounding conductor sizes for low-voltage electrical systems up to 750 volts. This article discusses the complexities of this rule, which as you know, was revised in the 2009 Canadian Electrical Code. Read more

Canadian Perspectives

Tables 11 and 19 in the CE Code — are they necessary guides to the Code users or obstacles of using approved equipment?

by Ark Tsisserev

It should be noted that the vast majority of electrical equipment is made "approved” by its certification to an applicable CSA safety standard for electrical equipment. All such current product standards (known by the industry experts as "Part II” standards) are referenced in Appendix A to the CE Code, Part I. In fact, the installation Code is called the "CEC, Part I,” as the CSA safety standards for electrical products represent the "CE Code, Part II.” Read more

Safety in Our States

Flex Your Network & Phone A Friend…Knowing Your Resources

by Thomas A. Domitrovich

It is impossible to know the answers to all of the questions we are faced with on a regular basis; each job site will have unique and nuanced requirements. That said, it is critical to know appropriate and knowledgeable resources. Early in my career with Eaton Corporation, I worked in a technical application call center that took technical calls on advanced products manufactured by Eaton. I learned a valuable lesson in those years of my career: a sense of ownership is key to success, and you are as knowledgeable as the most knowledgeable resource programmed in your cell phone or stored in your email contact database. How you build that database is most important. Read more

UL Question Corner

Can Listed Water Heaters be Cord-and-Plug Connected?

by Underwriters Laboratories

No, UL has not Listed cord-and-plug connected central air-conditioning equipment or central heating furnaces. Read more

UL Question Corner

Does UL apply a Listing Mark to a product based on evaluation to an Outline of Investigation?

by Underwriters Laboratories

Yes, in cases where a published UL Standard does not cover a product submitted for investigation and certification, an Outline of Investigation may be used and contains basic requirements for such products. Read more

Recent Issues

May-June 2010March-April 2010January-February 2010November-December 2009September-October 2009

By Issue Date:
By Section