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July-August 2006
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July-August 2006 CoverJuly-August 2006


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VFDs for Energy Savings in Hospitals – what they are, how they work, and how they save money

by Mike Olson

A variable frequency drive (VFD) is an electrical device we use to control the speed of a standard three-phase ac induction motor. The number of poles designed into a motor and the frequency applied to the motor determine the motor base speed. We can conveniently adjust the speed of a motor by changing the frequency applied to the motor. You could adjust motor speed by adjusting the number of poles, but this is a physical change to the motor. It would require rewinding, and would result in a step change in the motor’s base speed. So, for convenience, cost-efficiency, and precision, we change the frequency (and voltage). At any given frequency output of the drive, you get a new torque / speed curve from the ac motor. Read more

Perspectives on PV

* Achieving The Art of The Possible

by John Wiles

Those who have been following this series of articles for the last year or so may wonder what is involved in designing and installing a code-compliant, durable, reliable, and cost-effective PV system. Utility-interactive photovoltaic (PV) power systems are a mature technology. PV modules have warranties to 25 years and are predicted to produce significant amounts of power for 30 years or more. Inverters have warranties to 10 years and estimated life spans of 15 years or more with even greater longevity predicted in the future. PV systems can be designed and installed following existing guidelines and codes that will achieve long life, durable service, excellent safety, and cost effective power production. However, it is evident that great numbers of systems being installed today will not achieve the art of the possible because of poor design and installation practices. This article will address some of the steps that the PV systems vendor/designer/installer must accomplish to achieve a safe, durable, reliable, and cost-effective system. Read more

Article 675 – Electrical Driven or Controlled Irrigation Machines

by Robert McCullough

Welcome to the Rodney Dangerfield of NEC articles! Irrigation machines? Most of you will labor your entire electrical careers without ever having seen one of these, let alone inspect or wire one. Back in 1973, proposal number 115 was submitted to code-making panel 11 by the Technical Subcommittee on Electrically Driven Center-Pivot Irrigator Systems. This proposal was to add a new article 675 to put in place requirements that dealt with the unique characteristics of this type of equipment. It is no surprise that it was proposed for Chapter 6; if this isn’t special equipment, I don’t know what is. Read more

Should Changes at "The Fed” Affect How You Invest?

by Jesse Abercrombie

It’s been a long time since someone other than Alan Greenspan has served as chairman of the Federal Reserve Board of Governors. In fact, Greenspan has been at his current job since 1987. But in a few weeks, we’ll see a "changing of the guard” as Ben Bernanke takes the helm at the Fed. This is big news for economists and policymakers, but what about individual investors in the electrical business? How will you be affected by the emergence of a new Fed chairman? Read more

Choosing the Right Interconnect Solution for Your Application

by Paul Carter

The world’s population, although greater than ever, is also more connected than ever. We are linked by satellite, Internet, fiber optic cables, and high tech communication cords. We transmit data and power in fractions of seconds, often not giving a moment’s thought about the sophisticated technologies that allow these transmissions to take place. Read more

Buyers Beware: Electrical Instrumentation for Use in Hazardous Locations

by Robert (Bob) Baker

Buyers of salvaged, remanufactured, refurbished or new surplus electrical instrumentation for use in hazardous locations (including chemical process plants, refineries, and other industries/applications which are classified as hazardous) need to exercise caution in their instrumentation purchases. Doing so is especially important given the increased market for these items, which experts estimate at $100 million for the process industry and growing. There are several factors responsible for the rapid growth in this market: industry pressure for cost containment (maintenance budgets and small, local capital projects), increased overseas competition and the ongoing closure of North American chemical and hydrocarbon processing facilities. Read more

Analysis of Changes, Part 1, NEC-2008

by Michael Johnston 

Revisions to the NEC are inevitable, and given the unique and important nature of this electrical safety standard, very necessary. The NEC development process is ever dynamic and ongoing, because new technologies are continuously entering the electrical market and code rules must be developed or revised to address electrical safety concerns related to these new materials, equipment, emerging methods or technologies. There were 3,688 proposals, including all technical committee proposals, to change NEC-2008. These proposed changes were acted on by the technical committees at the Report on Proposals (ROP) meetings held in January 2006. This article provides an overview based on code-making panel actions taken on the proposals in the first stage of the development process. Read more



Be All You Can Be! Come to your section meeting

by James W. Carpenter

It is the middle of the summer and fall is just around the corner. Likewise, IAEI’s annual section meetings are approaching. This issue of the IAEI News highlights the six section meeting locations and programs. I always get excited about now, looking forward to traveling to all the great locations that have been selected to hold these meetings. Cities like Spokane, Washington; Traverse City, Michigan; Ottawa, Canada; Philadelphia, Pennsylvania; Fort Worth, Texas; and San Diego, California are where we are scheduled to go this year. Meeting new people, getting reacquainted with friends, and sharing all the many things that we have experienced in the past year is always exciting. What a wonderful opportunity to get together. Read more

Canadian Code

Tricky Rules

by Leslie Stoch

Several of the rules in the Canadian Electrical Code are quite complicated, and it requires our close attention to get them right. This article discusses two of those rules, 28-604 for motor disconnects and 4-004 for underground conductor ampacities. Read more

Canadian Perspectives

Emergency Lighting and Exit Signs Application and Installation Requirements

by Ark Tsisserev

Application of certain types of electrical equipment may be governed by codes other than the Canadian Electrical Code (CEC). Emergency lighting and exit signs are good examples of such types of equipment. Read more

Other Code

The 2007 NESC – Part 3

by David Young

This article is a continuation of what I see as significant changes that are coming in the 2007 revision of the National Electrical Safety Code. Read more

UL Question Corner

What are the new listing requirements for GFCIs and when will they go into effect?

by Underwriters Laboratories

Effective July 28, 2006, new requirements go into effect in the Standard for Safety for Ground Fault Circuit Interrupters, UL 943. These requirements are to address new requirements for an end of life test and for a revised miswiring test. Read more

UL Question Corner

What happens if I use the factory provided holes in the bus?

by Underwriters Laboratories

Switchboards are Listed under the product category Deadfront Switchboards, (WEVZ), located on page 264 of the 2006 White Book or online at and enter the Category Code WEVZ. Switchboards are not Listed for drilling holes in the buswork in the field and tapping branch circuits off of the bus. Read more

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