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July-August 2007
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July-August 2007 CoverJuly-August 2007


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Electric Shock Drowning

by James D. Shafer

Abstract Yachts moored in a marina and connected to shore power present a unique electrical safety hazard which may be as lethal as the proverbial "hair dryer in-the-bathtub.” This review will explore the implications of this and what we have learned from investigating many in-the-water electrical accidents, a number of which have involved fatalities. Read more

Perspectives on PV

* Continuous Currents through Curious Cables

by John Wiles

When inspectors see a photovoltaic (PV) power system for the first time, they will usually be faced with a type of wiring method not normally seen in residential or commercial electrical systems. That wiring method is the use of single-conductor exposed cables to connect the individual PV modules together in the PV array and is permitted by NEC 690.31. Exposed, single-conductor wiring is usually seen only in older neighborhoods as aerial feeders between buildings and in obsolete (but still with us) knob-and-tube wiring systems. Read more

Calculated Demand and Underground Ampacities

by Robert Edwards

The main thrust of this article is to establish that Section 8 of the Canadian Electrical Code Part I does not have adequate rules to address derating factors for continuous loads, or to calculate the minimum ampacity requirements for the safe sizing of conductors and electrical equipment, when the underground ampacity calculation is performed to size conductors, and to propose how solutions to these issues should be developed. The current derating factors for continuous loads apply strictly to installations above ground. Read more

Summer Camping Electrical Safety

by Bruce A. Hopkins

As the season of sun comes upon us, many folks will be planning their summer vacations. To enjoy the freedom of adventure and flexibility, camping is the perfect family getaway. Whether one is using a folding camping trailer, a full-sized motor home or any of the many other models of recreational vehicles (RV), fun is the key motivator. However, as with anything, safety is a primary concern and needs to be investigated to ensure that fun is the memory of the summer. Read more

Illegal Multi-Family Dwelling

by Bart Archibald

Connecticut had experienced unseasonably warm weather for the months of November, December and January, with days reaching into the sixties, but by February, winter had returned with a vengeance with nighttime temperatures declining into the minus six degrees range. Read more

A Swimming Pool Is Just a Big Bathtub, Isn’t It?

by Jim Maldonado

The answer to this question is yes and no. That sounds like an answer from an inspector, doesn’t it? Yes, it is just a large container of water, but when you mix electrical equipment, such as pumps, heaters, and lighting with this large container of water, there can be problems. Article 680 addresses "…all swimming, wading, therapeutic, and decorative pools; fountains; hot tubs; spas; and hydromassage bathtubs, whether permanently installed or storable…” (680.1 Scope). Read more

Isolated Power Systems in Health Care Facilities

by Michael Johnston

Grounded Systems Generally Required Generally, electrical systems used in power distribution systems for premises wiring are required to be grounded. The NEC includes rules that often make this determination. Some electrical systems are required to be grounded, while other systems are permitted to operate ungrounded (see 250.20 and 250.21). Read more

To Build Wealth, Look at Both Sides of the Balance Sheet

by Jesse Abercrombie

At a recent golf tournament for the construction industry, I spoke with a gentleman about a once very successful contractor who is no longer in business. I instantly figured that the gentleman had sold his business and pursued other endeavors. However, I found out that although he was successful, every dollar he made was spent on homes, cars and boats. This isn’t as common in the construction industry as it is in other industries, but I see more and more business owners get leveraged right out of business. Read more



IAEI and the NEC Code-Making Panels

by James W. Carpenter

Now that the cycle for the 2008 edition of the National Electrical Code is almost complete, IAEI must begin planning for the next cycle. IAEI continues to play an important role in the NFPA consensus code-making process by supporting inspector members on the code-making panels of NFPA 70 – National Electrical Code. Questions have been asked by members concerning the way IAEI selects inspector members for nomination to the various code-making panels. Let’s examine the process. Read more

Canadian Code

Substation Grounding

by Leslie Stoch

Section 10 of the Canadian Electrical Code, Grounding and Bonding, is probably the least well understood section of the electrical code, but it is one of the most important. Opinions abound on the absolutely correct interpretations. But almost everyone will agree that correctly installed grounding and bonding is most critical to a safe electrical installation. Read more

Other Code

What are you paying for electricity? Part 3, Commercial 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. In this segment, I am going to share with you and discuss in detail the small commercial 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. Some of the terms I am using in this article have been previously defined and discussed in parts 1 and 2 of this series. Read more

UL Question Corner

I was told that I could not plug one extension cord into another on a construction site. The NEC does not seem to prohibit this practice. Where do I find such information?

by Underwriters Laboratories

UL Lists what every one knows as "extension cords” as cord sets under the product category Cord Sets and Power Supply Cords (ELBZ), located on page 65 in the 2006 UL White Book or online at and enter ELBZ at the Category Code search. Cord sets and power supply cords are evaluated for compliance with the Standard for Safety for Cord Sets and Power Supply Cords, UL 817 Read more

UL Question Corner

I am a Canadian electrical inspector and want to know what is the UL White Book and is there a UL White Book for Canada?

by Underwriters Laboratories

The UL White Book is a regulatory reference tool that UL provides to AHJs and others to verify the Listing scope of UL Listed electrical products installed in the field. The Guide Information for each UL product category details the scope of the Listing, important installation and marking information, identification of the standard or other requirements used for Listing as well as how to identify products Listed under the product category. Read more

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