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May-June 2007
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May-June 2007 CoverMay-June 2007


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Overcurrent Protection, Part 2

by Tim Crnko

Part I, which appeared in the March/April issue, provided readers with information about basic operation and basic time-current characteristics of branch-circuit, low-voltage fuses and circuit breakers. This article covers three overcurrent protective device ratings, their application in design, and NEC compliance aspects of low-voltage branch-circuit fuses and circuit breakers. Read more

Perspectives on PV

* Disconnect, Disconnect, Where For Art Thou?

by John Wiles

The requirements and necessity for, and the location of disconnects in a photovoltaic (PV) power system are always of great interest. While PV equipment manufacturers, designers, installers, and electrical inspectors are all interested in getting safe PV systems, there are usually some "friendly” discussions on the whys and hows of disconnects needed to achieve those ends. The following information may shed a little light on those sometimes elusive disconnect requirements and how they can be addressed. Read more

Electrical Safety: A Changing Environment

by Jim Dollard

What does the term electrical safety really mean? Stop reading for a moment and think about what electrical safety means to you. The hazards are electrical shock, arc-flash and arc-blast. Electrical safety is achieved by taking all of the necessary steps to provide our homes with safe electrical systems... Read more

Connecting with Aluminum

by Jacqueline Silvia

When deciding what type of connector material works best in an electrical application, specifiers and inspectors alike may instinctively assume copper is the best choice. And indeed, it may be. But there are some applications for which aluminum poses a cost-effective, easier and longer lasting alternative. Read more

Concrete-Encased Electrodes Required

by Joseph Weigel

Electrical arc-flash and shock hazards have been recognized as particularly dangerous and fairly frequent occurrences that put the lives and health of electrical workers at significant risk. Statistics indicate that five to ten arc-flash accidents that involve a fatality or serious injury to an employee occur every day in the United States. Read more

Case Study: A Fragile Environment in a Rugged Climate

by Todd Wimmer

Behind the scenes, a lot of mechanical engineering goes into creating and maintaining a tropical rainforest near Lake Erie, just 40 miles from the Canadian border. It is a feat accomplished by Cleveland (Ohio) Metroparks, a recreational authority that provides an "emerald necklace” of woodlands, golf courses, hiking trails and other attractions surrounding this Midwestern... Read more

When Disconnects Are Not Enough

by Michael Johnston

May is electrical safety month, during which the electrical industry draws attention to all aspects of electrical safety for persons and property. Section 90.1(A) of the NEC provides the essence and basis for this concept that is integral to the rules in the Code. Read more

Utility Deregulation, What Does it Mean to Inspectors?

by Len Frier

Deregulation of electric utilities is sweeping the country and is now available almost everywhere. The theory is that competition in the purchase of electric power would result in cheaper electricity and make utilities more responsive to consumers. This may be good in some areas and bad in others but it does put certain new elements of an electrical system under the authority of the local jurisdiction. Here goes…. Read more

The Texas Margin Tax: There’s a New Tariff in Town

by Jay D. Crutcher, Esq.

There’s a new tariff in town called the Texas Margin Tax. The margin tax replaces the old franchise tax and affects virtually every business entity in Texas (including out-of-state companies "doing business” in Texas). Vast numbers of limited partnerships, previously exempt from the old franchise tax, will now pay margin tax and it could be a sizeable amount. Read more




by James W. Carpenter

There are signs all around us telling us what to do, warning us of danger, and some we are not aware of until it is too late. There are all kinds of signs along the roads we drive on, telling us to stop, merge, or curve ahead. Speed limit signs—I suppose many of you can relate instances where nobody seems to obey the posted speed—are also seen along the roads we travel. We know the signs of spring; the grass turns green, the trees bud, and the flowers bloom. We are aware of all the seasons of the year by the signs we recognize. Read more

Canadian Code

Allowable Ampacities – Conductors in Cable Trays

by Leslie Stoch

In my experience, a discussion of conductor numbers and ampacities in cable trays is frequently met with a snicker or knowing smile. Could it be that the rule for wiring in cable trays is sometimes taken less than seriously? We have all seen trays overloaded with cables, if not at the time of installation, then in the fullness of time. Once the trays are in place as originally designed, it’s far too easy to add cables, especially when the trays follow a convenient route to the end destinations of the added cables. Read more

Other Code

What are you paying for electricity? Part 2, Residential Electric Rates

by David Young

To protect your and your company’s wallets, it is very important to understand the rates for which you are being charged for electricity. To get your feet wet, I am going to share with you and discuss in detail the electric rates of a typical utility. The example I am using is a utility that publishes their rates on the Internet. The electric rates for which you are being billed may vary greatly from my example. I recommend that you contact your utility to get a copy of your rate and find out what other rates are available to you. In most states, if a residential, commercial or industrial establishment wants electric service, they do not have a choice as to the service utility. Read more

UL Question Corner

Are all split bolt clamps Listed to be used for connecting copper grounding electrode conductors to steel rebar direct buried in earth, and if so how can these clamps be identified?

by Underwriters Laboratories

Typical split bolt connectors are not Listed for connection of a grounding electrode conductor to rebar, they are intended for connection of two conductors in an ordinary dry location inside an enclosure and are Listed under the category Wire Connectors, (ZMVV) located on page 307 in the 2006 UL White book or online at and entering ZMVV at the Category Code Search. These type of split bolts connectors are not intended to be used for grounding applications to connect a grounding electrode conductor to rebar or any other component of the grounding electrode system. The Listing Mark on the connector or packaging would identify it as a wire connector. Read more

UL Question Corner

Does UL List the spiralshaped compact fluorescent lamps (e.g. light bulbs)?

by Underwriters Laboratories

UL does List the spiral shaped types of compact fluorescent lamps (CFLs) that are very popular right now. These types of lamps consist of a self-contained fluorescent tube and ballast in an enclosure with a medium base screw shell adapter that will screw into any medium base lamp holder. This category also covers self-ballasted lamps employing light emitting diode (LED) lights. Read more

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