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May-June 2011
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Article 110, Requirements for Electrical Installations

by Randy Hunter

In the last issue we discussed the NEC requirements up through 110.14, Electrical Connections, so we will start with 110.15, the requirement for identifying the high leg. Now you’re probably asking, what is ahigh leg? To answer that, we have to review some of the basics related to voltages and transformer windings and connections. We have two basic transformer configurations, wye (Y) and delta (∆). Read more

Perspectives on PV

Changes and Challenges

by John Wiles

For nearly a century from about 1897 to 1997, premises wiring systems in residences and commercial buildings have largely been collections of passive conductors, disconnects and overcurrent devices. Certainly there have been incremental improvements in these systems and they can be quite complex with the addition of transformers, motor controllers, GFCIs and AFCIs, but much of that complexity is due to the connected loads that are not covered in inspections under the requirements of the NEC. Read more

Electrical Plan Review in the Emerging Renewable Economy

by Jonathan Cadd

Get ready for the new future of the renewable, alternative, everything-we-can-invent-and-provide-an-infrastructure-for era. The second wind of the 21st century is upon us, and the best technological minds available have joined forces to help consumers and users of these new technologies usher in this bright new future. With the flood of these new technologies growing daily by leaps and bounds, we now have to look toward global solutions to harness the power that is to be provided in various ways by these emerging technologies. Read more

Electric Vehicles Turn Homes and Offices into Fuel Stations

by John R. Ferris

Electric Vehicles (EVs) are expected to account for as much as 15 to 20 percent of annual vehicles sales worldwide, which means millions of vehicles that use electrons as power will be plugging into the grid. What does that mean for electrical inspectors and those who write building codes across the U.S. and around the world? Read more

IAEI’s Role in Electric Vehicle Infrastructure Training

by David Clements

As society moves towards emerging technologies, there come many challenges. This is true with introduction of the electric vehicle. It should be as simple as telling the owner of an electric vehicle "all you need to do is plug your vehicle into an outlet and charge the battery.” However, we all know that there are major factors that must be first considered: electrical infrastructure to accommodate the charging equipment, utilities to ensure they meet the power demands, safety requirements for first responders, training for inspectors, electrical contractors, electrical design engineers and the list goes on. Read more

The Tragedy of Complacency — Improving Safety with Gratitude

by Steve Foran

Complacency causes accidents. Although many other factors come into play in the prevention of accidents, few are simpler to overcome than the state of being complacent. Read more

Electric Vehicle Charging

by Christel Hunter

Car buyers who wish to take advantage of new technology electric vehicles — either battery electric vehicles or plug-in hybrid vehicles — have several choices. With no additional electrical system upgrade to their home, battery electric vehicles and plug-in hybrid electric vehicles can be charged using a standard 120-volt, 20-amp receptacle. This is referred to as Level I charging. Unfortunately, a full charge at this voltage can take quite some time, generally estimated at 8–20 hours. Read more

Copper Protects MIT Computer Center

by David Brender

When one of the nation’s leading technical institutes sets out to design a new center for computer, information and intelligence sciences, top-quality electrical power was high on the list of must-have features. Why? Because all of the sensitive electronic equipment in the center would need clean, stable power, or the equipment simply would not work as it should. And so, in 1999, when the Massachusetts Institute of Technology began planning the Ray and Maria Stata Center as part of its campus redevelopment program, planners gave very careful attention to the new structure’s electrical and grounding systems. Read more

"Hazardous Locations” Not Confined to Article 500 Installations

by Andre Cartal

If you have been an inspector for any length of time, you already know that "hazardous locations” often exist in other than Article 500 installations. The following four photographs demonstrate this situation. Read more

Basic Electrical Calculations

by Stephen J. Vidal

Electrical calculations generally fall within two categories: dc circuit analysis and ac circuit analysis. In a typical engineering curriculum dc circuit analysis is introduced first with resistive networks. Once all the network theorems are discussed and evaluated, ac circuit analysis is introduced. AC circuit analysis is more complex and requires the use of calculus if the circuits are evaluated in the time domain. Usually the concepts of inductive reactance, capacitive reactance, and impedance simplify the circuit analysis in the frequency domain. Read more

Performance Meter Socket Configurations

by Peter Pfeifer

Because meter sockets are now being installed on the other side of a customer’s load center, as part of PV installations, it is important for an inspector to understand the terminal configurations to help ensure the equipment was installed in a safe manner. Read more



A sure way to win…

by Kathryn Ingley

Technology seems to always start out huge and bulky and becomes smaller, streamlined and faster as it is refined; and because it seems to need less input from humans, we either embrace it intuitively or we reject it and act disinterested. Sometimes we embrace technology so strongly that we begin to feel it is virtually infallible, or we expect it to supersede all previous technology. Not so. Read more

Canadian Code

Electrical Equipment Vaults

by Leslie Stoch

The Canadian Electrical Code defines a vault as "an isolated enclosure either above or below grade with fire-resisting walls, ceilings and floors for the purpose of housing transformers and other electrical equipment.” This article discusses the CEC requirements for electrical equipment vaults designed to house flammable liquid-filled equipment. Read more

Canadian Perspectives

Consistency in requirements for electrically connected life safety systems in different Codes and Standards

by Ark Tsisserev

In general, electrical designers, contractors and regulators are quite comfortable in applying the CE Code requirements for the electrically connected life safety systems. Read more

Safety in Our States

A Counterfeit Challenge

by Thomas A. Domitrovich

Our industry is experiencing a challenge that jeopardizes safety: growth of counterfeit products. The act of counterfeiting is not new to our society and can, in fact, be traced to ancient times — the Romans fell victim to fake currency. Back in 1862, the U.S. Government established a national currency due to the counterfeiting problem at that time. Then in 1865, the Secret Service was established to stop the spread of forged money in the United States. Simply take a look at a few bills in your, or preferably a friend’s, wallet. Read more

UL Question Corner

Is there anywhere I can get a repository of UL Question Corner columns in one place and organized by topic?

by Underwriters Laboratories

Yes, UL has a repository of UL Question Corner columns going back to the year 2000 located on UL’s recently enhanced Code Authorities web pages located at The Code Authorities page on is the website for UL’s Regulatory Services Department that is charged with supporting the UL Mark by supporting you, the users of UL’s certifications. Read more

UL Question Corner

Can a manufacturer add labels to a UL Listed product in the field, even if the label is not a Listing Mark?

by Underwriters Laboratories

No, when you add labels to a Listed product after it leaves the factory, it is considered a Field Modification. The product was never reviewed to determine if the attribute identified on the added label or marking is accurate or continues to comply with UL’s requirements. In order for UL to determine if that product still complies with UL’s requirements, UL would have to conduct a Field Inspection or Field Evaluation to determine if the modifications are still in compliance with the UL’s requirements. Read more

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