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Introduction to Transformers

by Stephen J. Vidal

A transformer is an electromagnetic device without any moving parts that allows for changes in voltage, current, and impedance. The goal of an ac power network is to generate a voltage on the generation side, step up the voltage for long distance transmission on the transmission side, and then step down the voltage for distribution to the load on the distribution side. Let’s look at an example. Read more

Perspectives on PV

A Critical Look at Load Side Utility-Interactive PV Inverter Connections 690.64(B) / 705.12(D)

by John Wiles

The NEC in sections 705.12(D) / 690.64(B) allows utility-interactive photovoltaic inverters to be connected on the load side of the service disconnect. This requirement has been in theCodesince the late 1980s when PV Article 690 first appeared. Except for a slight change in 2008, the requirement has been largely unchanged. A critical examination of the requirement and how it can be applied as well as various proposals that have been rejected over the years may yield insights on what is needed in the future. Read more

Electrical Inspections for the Combo Inspector, Part 6. Article 200, Use and Identification of Grounded Conductors

by Randy Hunter

This is the part of the NEC where new code students often start to become confused. It is essential to clearly explain the difference between grounded and grounding, and then find a way to etch this into the student’s mind so he or she will not confuse or misuse the terms. Therefore, we will go into detail to clearly identify the difference between the two terms. Read more

Over Code: The Anatomy of a Code Change Proposal

by Thomas A. Rorro, P.E., E.I.

The purpose of this article is to consider the requirements for bonding in 2011 National Electrical Code (NEC) 250.104, Bonding of Piping Systems and Exposed Structural Steel.1 Consider the simple hot and cold water lines on a 10-gallon ceiling-mounted hot water heater shown in figure 1. The heater serves a single sink in a small lunchroom directly below the heater. Read more

DC: The Return of the Titan

by Jonathan Cadd

With both the home and the workplace seemingly powered by alternating current (AC), the question has been asked throughout the electrical industry, Has direct current (DC) really gone the way of the old Ford Model T? Quite the contrary, direct current is alive and well. In this article we will look at the origins of AC and DC power and see how the two differ. Read more

Know Your Investment Risks and How to Respond

by Jesse Abercrombie

When you invest, you take some risks. While you can’t totally avoid these risks, you can take steps to help reduce their impact and increase your comfort level. And the more comfortable you are with your investments, the easier it will be to follow a long-term strategy that can help you meet your goals. Read more

Gratitude – the Common Denominator between Giving and Safety

by Steve Foran

Recently I found myself attempting to explain to a close friend and business associate why I left my job to start a new line of work. At some point in our conversation I said, "I have a need to give and I believe that everyone has this need to give, to serve, to help others.” I explained to him that it was born out of gratitude for everything that I had received in my life … a life that, I am sure like your life, has its share of hardships. Read more

Are You the Weakest Link?

by Christel Hunter

Good workmanship requires that the professional electrician make sure that equipment is suitable for the installation and used in ways that comply with applicable codes and job requirements. Since most electrical equipment must be physically connected by some form of conductor, those connections are critical to the long-term reliability and safety of the installed electrical system. Developing good connection techniques and understanding what makes a good connection are the hallmarks of a professional electrician. Read more

10 Ways to Protect Your Family from Fires

by Allen Wright

According to the National Fire Protection Association (NFPA): In 2009 there were 1,348,500 fires reported in the U.S., resulting in over 3,000 deaths, in 17,050 injuries and in property damage of $12.5 billion. One home fire was reported every 87 seconds. Households can expect to average a home fire every 15 years or five fires in an average lifetime. Read more



Risk comes from not knowing what you’re doing

by Kathryn Ingley

Know what you’re doing — not a bad lesson for us. At least I’ve found that continually adding to my knowledge keeps me alert and helps me to avoid errors better. That same concept underlies IAEI’s focus on CEU training and the huge emphasis placed on the Certified Electrical Inspector programs in the United States and Canada. Most writers in this issue focus on increasing our knowledge and applying it to installations and inspections and to examining current codes and making proposals for revisions or additions. Others apply the concept to investment, family safety, and training our successors. Read more

Canadian Code

What’s Wrong with Rule 14-100?

by Leslie Stoch

Rule 14-100 has requirements for reducing wire sizes connected to splitters, junction boxes and for control circuits such as pushbutton stations. The rule prescribes the minimum construction requirements for mechanical protection and maximum unprotected lengths of conductors so as to produce a safe installation. The rule is consistent in its overall requirements except for Sub-rule 100(d), which appears to be totally at odds with the remainder of the rule. Read more

Canadian Perspectives

Safety and performance of Codes

by Ark Tsisserev

Any electrical design and installation is based on a number of conditions. Traditionally, such conditions include reliability, performance and economics. Usually these conditions are dictated by the clients, who want such installations to function in a dependable manner and to be economically feasible. Read more

Safety in Our States

IAEI West Virginia: Getting Back to the Grass Roots of Safety

by Thomas A. Domitrovich

New electrical contractors enter our markets every year; these individuals perform work that electrical inspectors ultimately review. Involvement in activities in which these individuals participate, using the opportunities to educate, is getting to the grassroots of electrical safety. The IAEI West Virginia recognized an opportunity to be a leader in safety through involvement with the Skills-USA program in their state. Read more

UL Question Corner

When is the 2011 UL White Book available, and what is new for 2011?

by Underwriters Laboratories

The 2011 UL White Book started distribution April 1, 2011. The UL White Book is considered by many as "Part 2 of the Code.” That is because without the White Book, it is difficult to determine compliance with the National Electrical Code (NEC). Read more

UL Question Corner

Has UL investigated the effects of spray-on foam insulation on Type NM cable jackets or individual conductor insulation?

by Underwriters Laboratories

UL has not specifically investigated the effects of spray-on foam building insulation on the jacket or insulation materials of NM cable. UL Lists NM cable under the product category Nonmetallic Sheathed Cable (PWVX), located on page 293 in the 2011 UL White Book and online at and enter PWVX at the category code search field. Read more

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