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IAEI News provides educational forums, updates on electrical codes and reports of innovative research to facilitate the development and enforcement of practices designed to drive efficiency and compliance with the highest standards of product development and safety—for the public as well as for electrical personnel. The magazine reaches authorities with power of product specification, approval and acceptance. Published six times a year by the International Association of Electrical Inspectors.

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Case Study: Arizona Cardinals’ new state-of-the-art retractable stadium roof

Posted By Michael W. Vallier, Wednesday, November 01, 2006
Updated: Sunday, February 10, 2013

As professional sports venues become bigger and more complex in design and scale, architects and engineers are looking for bold new ideas. Retractable roofs have become a popular feature in those structures because they provide the ability to control the stadium’s interior environment more effectively. Only a select number of companies have the knowledge and expertise to mechanize and control these immense structures, which, themselves, become architectural feats.

Uni-Systems, based in Minneapolis, Minnesota, is just such an expert. Whether it’s a retractable roof, a retractable pitcher’s mound, movable walls or seating, Uni-Systems has established itself as the industry’s premier provider. The company’s impressive resume includes work on Minute Maid Park and Reliant Stadium, Houston, Texas; Miller Park, Milwaukee, Wisconsin; RFK Stadium, Washington, D.C.; and most recently, the Arizona Cardinals’ Stadium, Glendale, Arizona.

Photo 1. New Arizona Cardinals state-of-the-art retractable stadium


Photo 2. Cable drum with bull gear

With its curved roof track, the Arizona Cardinals’ project presented interesting challenges in designing the retractable roof mechanism. Uni-Systems partnered with ABB and selected the ABB ACS800 drive to provide optimum control of the roof’s torque-distribution system.

Building an Architectural Oasis in the Desert; Take the Grass Outside

When the National Football League’s Arizona Cardinals made the decision to construct a new arena several years ago, the desert climate was a major consideration in the design plan. The heat can take its toll on fans and players, alike, and can be detrimental to the playing surface, as well — especially if it’s natural grass. On the other hand, in cooler months, the world-famous climate is perfect for hosting outdoor activities.

The exterior design of the stadium resembles the basic form of the barrel cactus and was created by renowned architect Peter Eisenman, along with HOK Sport. The retractable roof can be closed so the facility can be air conditioned in the hot months, and then opened in the cooler months. The roof’s panels consist of a PTFE (polytetrafluoroethylene) coated woven fiberglass fabric, and are much lighter than a traditional, clad roof. The stadium design includes not only a retractable roof, but also a retractable playing surface.


Photo 3. 8 ACS800 drive control 16 motors per roof quadrant

The innovative, roll-out field will save an estimated $50 million in operating costs, as it is more economical to move the field outside, rather than having the entire roof retract to allow the necessary sunshine to reach the grass. The retractable, natural-grass playing surface is contained in a 16.9-million pound tray that is 234 ft wide by 400 ft long — the first of its kind in North America. All in all, the design of the stadium is so unique that, to date, it’s been featured in a multiple series on "The Discovery Channel.”

Direct Torque Control Provides More Accurate Feedback; Drive Proves Torque at Motor

This roof was different than any that Uni-Systems had previously constructed. According to Lennart Nielsen, Danish master electrician and senior electrical designer with Uni-Systems, one of the most important decisions was selecting motor drives to control the roof’s movement.

"An important factor in choosing the ABB drives was the inherent risks associated with running a roof on a sloped track,” says Nielsen. "This caused us to look for a variable frequency drive (VFD) that would allow us to test the drive torque before each roof motion, to ensure that each drive was operational and capable of a 100-percent torque output. The ACS800 was capable of this, so before each motion, the programmable logic controller (PLC) checks the torque output from the VFDs at 0 Hz, before committing to opening the motor brakes.” Nielsen also says the ABB drives could be installed and operated without the need for closed-loop encoders — a cost-effective option that helped the company meet budget requirements.

Nielsen explains that for other roofs that Uni-Systems designed, if the brakes were to release and the motors didn’t start up for some reason, the roof would simply remain in place. However, at the Cardinals’ new stadium — with its sloped roof track — if the brakes were released and the motors didn’t start up, the roof sections would fall into the parking lot.


Photo 4. Each retractable roof panel is raised and lowered on a steep slope

"The ABB set-up, with their direct torque control, can measure the feedback from the motor much more accurately than a standard drive,” says Nielsen. "And in their control/output algorithms, they can measure the characteristics coming back from a motor at 0 Hz (meaning that they start the energy field but don’t rotate it), and that’s a big reason why we chose them.”

"We wanted to have this capability all the way down to 0 Hz, and none of the manufacturers — except ABB — could guarantee that,” Nielsen continues.

ABB Drives Critical to Roof Functionality

The retractable roof consists of two moveable panels suspended between two parallel tracks — along the east and west sides of the structure. The tracks are curved to follow the roof’s slightly domed profile, which slopes down from its apex at the 50-yard line towards the north and south ends of the building. Each roof panel rests on eight, two-wheeled carriers: four along the west and four along the east side of the roof panel; each set of four carriers forms one quadrant of the entire retractable roof system.

Conventional techniques — such as the powered traction wheels that Uni-Systems used on previous stadium projects — were not an option for the Arizona stadium’s sloped roof. Instead, Uni-Systems designed a system in which each roof panel is tethered by four 1.5 inch-diameter steel cables on each side.

There are two cables running on each side of the roof rail, and each is wound on its own 48-inch-diameter cable drum. The cable drums are arranged with one on each side of the two upper carriers for each roof panel quadrant, and the two lower carriers in each quadrant are not powered. Each cable drum is equipped with a bull-gear along the outer rim, driven by four, geared 7.5 HP, 480 VAC motors with spring-set brakes.

The four motors per drum are controlled by two 20 HP ACS800 VFDs, meaning that each roof quadrant is powered by 16 motors that are controlled by eight VFDs. Accurate control of the VFDs was essential to distribute the load evenly to the roof cables. "It was deemed inadequate to let the roof PLC act as referee for each individual drive via the ProfiBus that was to handle the regular data communications between the PLC, VFDs, and remote I/O,” says Nielsen. "Instead, we use a parallel, fiber-optic communications network between each group of eight VFDs, where one VFD was designated as Master and the other seven as Followers.”


Photo 5. Retractable roof panels nearly closed

Once the roof is moving, it is extremely important to keep a very tight torque-and-speed envelope around each Follower drive in relation to each roof quadrant’s Master VFD,” Nielsen continues. "The ultra-fast switching direct torque control system of the ACS800 provides the means for doing this via the fast intra-VFD fiber-optic network.”

The PLC issues a speed (frequency) command to each of the two Master VFDs (one per side) and the seven Follower drives then match the torque output of the Master drive. Each roof panel’s PLC handles the position alignment between the two quadrants of each roof panel, which receives position feedback from an absolute encoder in each quadrant and from incremental encoders on each cable drum. If a roof side gets more than two inches ahead of the other — the rails are 257 feet apart — the PLC will signal the Master of the leading side to slow down until the two sides are again in alignment.

Since the roof rails are curved, the actual cable load increases as the roof panel moves towards the fully open position and the steeper sections of rail. For optimum motor torque, the VFDs output 60 Hz at the lower half of the rails, and to decrease operating times, 85 Hz on the upper half. Motors operate in both motoring and generating modes — generating when the panels are lowered, and motoring to lift and close the panels.

The ABB drives require no maintenance. They are mounted in air-conditioned enclosures that are on the carriers.

Retractable Roof Quick Facts

  • Two retractable roof panels at 1,100,000 lb. each (550 tons)
  • Each roof panel’s dimensions: 185 ft. long by 285 ft. wide, 16 ft. deep
  • 8 cables (1.5 in. diameter) connect each retractable roof panel to the stadium structure at the 50 yard line (over ½ mile of cable used)
  • 32 motors (7.5 HP) power each roof panel (480 total HP for stadium)
  • 16 crane wheels (36 in. diameter) support each retractable roof panel
  • 595,000 lb. of mechanization equipment used to make the roof move
  • 257.5 ft. span of retractable roof over stadium bowl
  • Two rail lines with 175 lb./yd. crane rail (over ¼ mile of rail used)
  • Maximum travel speed: 25 ft./min. or ¼ mph
  • Total travel time: 11.5 min. (10 min. run time, plus 1.5 min. of slow speed for final positioning)

Cable Oscillation Tests Drives Capabilities

During initial testing at the Cardinals’ stadium, Uni-Systems found that natural frequencies in the drive cables caused some oscillation or whipping in the cables as the roof was opened. "And the faster we ran, the more pronounced it was,” says Nielsen. "We saw that the drives actually made it worse. As each cable oscillated, the anchor points of the cables would see a varying torque. The master drive would then react to those changes by increasing or decreasing its torque output. And its torque profile would then be transmitted to the other drives that reacted to it — causing the whole cable system to start into harder and harder oscillations.”

This was an unforeseen challenge, but ABB was there to help develop the solution. ABB engineers visited the site to help Uni-Systems get the drives tuned in to deliver optimum control and eliminate the bounce in the cable as the roof opened. Nielsen says, "Our natural reaction would have been to just open up the tolerances more to allow a larger window around the optimal speed and torque to allow a little bounce without the drives reacting to it. But ABB application engineer Steve Boren went the opposite way and actually made that window extremely small so as not to allow it to react harshly enough to cause the oscillation. So we got everything to smooth out and work extremely well.”

"We simply needed to utilize a standard software feature in the ACS800 which allows for Loadshare (Torque) Followers to have, also, an over-riding speed window about the Master drive’s coordinated speed reference,” Boren said. "Because of the uneven cable stretch, which can be viewed as slip between the driven cable drums, it’s tough to make the drums share the load evenly. But by activating the ACS800’s Speed Window capability in the torque follower drives, and limiting the window (slip) to only 2 rpm on each motor, the cable drums have no choice but to evenly share the load of the immense roof.”

"Our experience with ABB has been very good,” says Nielsen. "It’s not the first time we’ve used ABB drives, but it’s the first time we have used them in one of our stadium projects. ABB has been very responsive as far as both sending personnel out during our prototype testing and getting the drives adjusted for optimal performance on the final product.”

Future Projects Already in the Works

With the Arizona Cardinals’ stadium nearing completion, Uni-Systems and ABB will soon turn their collective attention to several more new NFL stadium projects. Already in progress in Indianapolis, the Colts are replacing the RCA Dome with a new, state-of-the-art retractable roof stadium. "The system required for that roof is much more complex,” says Nielsen. "Instead of a nearly one-to-one, width-to-length ratio, the Colts’ panels are around five-to-one. This has resulted in a five-rail design, rather than a two-rail as in the Cardinals stadium, and twice as many cables and drives. Also in progress is a design for the new Dallas Cowboys’ stadium. Both of these stadiums will use the newer ACS800-U11, or regenerative drive, which was not available when the Cardinals stadium was designed.” The Cardinals stadium design uses stand-alone regenerative drives working with the ACS800 VFDs.

As both Uni-Systems and ABB gain more experience in this niche business, expect even bolder designs in the near future.


Read more by Michael W. Vallier

Tags:  Featured  November-December 2006 

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The Value of Electrical Inspection

Posted By Michael Johnston, Wednesday, November 01, 2006
Updated: Sunday, February 10, 2013

There is significant intangible value in many of the things we take for granted. For example, essential resources such as the air we breathe and the water we drink and use are often taken for granted. Society expects these life essentials to be safe, and not much thought is given to how safe they really are. Only when an identified problem surfaces, do people get concerned and fear sets in. The electrical power and lighting that powers society has become a resource that is taken for granted. People generally don’t think twice about the electricity they use until it is not available. Then its lack is inconvenient and creates challenges they are not used to. The coffee has to be brewed in the morning and the TV has to work in the evening, not to mention meals that have to be cooked and laundry that must be washed and dried. Society just expects things to work. Another expectation is that the electrical system within their dwelling or place of business is safe.

Photo 1. An inspector at work

Why Is It Safe?

Did you ever wonder how safe an electrical system really is? Think about the dwelling where you live and the business where you work. Electrical wiring is often buried within the hollow, inaccessible construction of the structure, so it would be difficult to detect deterioration of the electrical wiring. Most people just assume it is safe. Out of sight, out of mind, so to speak, so the question arises, how safe is the electrical system, and what are the reasons it is safe? What impact would it have if it were not safe? Could the building be subject to fire? Could the residents or building occupants be subject to electrical shock or even electrocution? The answer is, when electricity is in the mix, all of these events are possible. So what makes our electrical systems safe? They are safe because of qualified persons installing and qualified electrical inspectors verifying that minimum requirements are met for installations that are essentially free of electrical hazards. This article looks at the value of qualified electrical workers, and specifically the value of qualified electrical inspectors and the unseen job they perform on a daily basis so an expecting society can live safely.

Qualified Electrical Work Force


Photo 2. Generator paralleling equipment

Working in the electrical field requires training, and lots of it. The uniqueness and intricacies of the electrical field warrant extensive training initially for one to become a qualified and competent industry professional and require continuing education. Many states and local jurisdictions have laws that require these qualified workers to be licensed and to maintain their licenses through continuing education. This is essential because the electrical field is so dynamic. New technologies, methods, and products are constantly being introduced and installed. Not only do qualified electrical workers need to stay informed and trained in current technologies and applications, electrical inspectors really do too. Staying current is an essential part of their jobs.

Unsung Heroes — The Electrical Inspectors

The responsibilities of a building safety inspector are enormous, especially so for an electrical inspector. The value of what they do is an intangible, necessary benefit to society. People not only expect the electrical wiring to work, they expect it to never fail, and they definitely expect it to be safe. The services provided by electrical inspectors can be compared to other professions that relate to safety, such as fire department workers, police department workers, and medical workers. The difference is that these aforementioned heroes are very visible to the general public. The services of building safety inspectors are not often visible to the public, but the resulting installation and service it provides is.

The Responsibilities


Photo 3. Installers work to achieve code-compliance; inspectors verify it

It’s a tough job, but someone has to do it. Does that phrase sound familiar? Think about the responsibilities of a police officer, a fireman, or a doctor. The safety services they provide help protect people and save lives. The services they provide are based on needs at a point in time. When people become ill, they seek the services of medical personnel. If a building catches fire, the fire department will respond, hopefully, in time to save the lives and the building if possible. The police officer responds to speeding vehicles, crimes being committed, and other actions requiring intervention of law enforcement. All of these services are associated with the safety of society, but are provided in a reactionary fashion for the most part. In comparison, the unsung heroes—the electrical inspectors—furnish services that proactively provide environments safe from the hazards of electricity which can injure or kill people just as quickly as do fire or crimes. Electrical inspectors can prevent the smoke from happening, yet they never get much credit. In fact, electrical inspectors usually get negative attention because of the job they must do, such as sometimes rejecting an installation, which is not necessarily the popular thing. So the inspector often gets a bad rap for doing a good job.

Benefits of Electrical Inspection

Although construction code inspectors are often viewed as a necessary evil, there are significant benefits of a quality inspection program. This article is built around the value of electrical inspection. When one takes a close look at the value of electrical inspection, a few things come to mind. One value is the peace of mind that comes from knowing an electrical system is essentially free from hazards because it was inspected. For many, this is the most important value, but the business of electrical code enforcement provides other monetary values. It might not be viewed as an economic value or advantage, but in the bigger scheme of business, a good electrical inspection and building safety program can result in significant value for consumers.

The Insurance Services Organization (ISO) is concerned with providing accurate assessments of the services jurisdictions provide that result in safer buildings. Where inspection departments are providing quality and sufficient building safety inspection and plan review services, those jurisdictions are awarded a rating that can often result in lower insurance rates. Sounds like a pretty good value, safety, peace of mind, and lower insurance rates. What are the ISO ratings awarded to the jurisdiction in your area? These can be a good indication of whether public safety is deficient and in need of improvements. The fortunate aspect of knowing this information and understanding its impact is that jurisdictions can become proactive so the services they continue to justify provide the desired results.

Another intangible value that electrical inspectors provide is the contribution to the electrical Code development process. The electrical inspector is represented on each NEC code-making panel. The value they provide is asserting the voice of code enforcement in this process to assure that the safety rules produced in each new edition are practical, understandable, and, most importantly, enforceable. The International Association of Electrical Inspectors is committed to supporting this Code development process for these reasons and to promoting electrical safety through uniform application and understanding of the electrical codes and standards. Electrical inspectors also provide value to the product safety standards development through their contributions on the standards’ technical panels and the UL Electrical Council. The electrical inspector provides diligent service to the industry in these two areas, but it all happens out of the limelight. The recognition is not important, the service is. That is why they unselfishly give their time and expertise to this segment of the electrical industry. Electrical inspectors are teachers as well. The job they perform usually results in learning.

The Electrical Safety System


Photo 4. Violations are evident to inspectors

From the beginning, the quest to understand and use electricity has been an adventure. Lives have been lost, injuries sustained, and buildings have burned. Not long after electricity was discovered and refined to a usable status, society was provided with significant evidence of its force and how dangerous and even lethal it can be when not installed and used properly. Insurance companies recognized early on that regulation of electrical installations and the use of electricity were necessary for safety of persons and property. Insurance companies played an important role in the initial development of the National Electrical Code we use today. The North American Electrical Safety system has had an unprecedented role in developing necessary codes and standards relating to the safe electrical installations. Safe electrical installations of today resulted from years of experience and knowledge gained by unfortunate events that led to losses. This is the harsh reality of this powerful force, that society views complacently. The electrical industry has a long history of establishing an unprecedented electrical safety system that is every bit as effective and necessary today as it was in the past. In many cases even more so, as a result of today’s more complex, intricate electrical power systems and their diverse use. The safety afforded by regulation cannot be taken for granted at all.

The electrical safety system is the reason society can live and function in an electrically safe environment. Some essential elements that make up the electrical safety system that provides this protection are the qualified electrical testing laboratories, manufacturers, a qualified electrical work force, and quality electrical inspection of installations, equipment and systems. Each of these entities plays an important role in the safety we are afforded. Without a doubt, safe electrical installations are the result of each of these entities fulfilling its role in the electrical industry. Without all of them working for the same objectives, safety can be, and often is, compromised. It’s something to really consider when asking questions such as how safe is an electrical installation? What are the contributing factors that ensure it is safe?

The Role of Manufacturers

How do electrical product and equipment manufacturers contribute to the electrical safety system? By building quality products that meet or exceed the minimum electrical product safety standards that have been developed and established through research and experience. Time has provided the opportunity to invent and develop electrical products and equipment and often through the school of hard knocks, electrical safety lessons were learned. It’s a shame that lives had to be lost, injuries sustained, and properties damaged or lost along the way, but that is the nature of this powerful force. Electrical equipment manufacturers have come to depend on the established electrical safety system for the success of their business. By manufacturing equipment to meet or exceed minimum electrical standards, there are reasonable assurances that it will provide the level of service anticipated by a wealth of continuous industry needs. By having electrical products evaluated and tested to developed standards, their products become very marketable in an electrical industry that creates such demand. These manufacturers find comfort in the third party evaluation and testing and product certification process because they understand how valuable it is from a liability, marketing, and safety standpoint. It stands to reason that our electrical safety system is very dependant on electrical equipment manufacturers fulfilling their role in producing and certifying products that will meet the minimum standards for safety while providing a supply to the electrical industry.

The Role of Safety Standards Development Organizations

Did you ever wonder what is behind an electrical product certification mark such as UL, CSA, ETL, MET, TUV, or others? These marks of electrical products serve as an indicator to the electrical industry and society that a product meets the safety criteria for which it is intended. There are many qualified electrical testing laboratories in the industry today. It has become big business, and rightly so, with the ever-expanding use of electrical energy. The role of the qualified electrical testing laboratory is to determine that electrical products are essentially safe by verifying they meet the minimum requirements in established electrical safety standards. This awards an electrical manufacturer with recognition as a qualifying contributor to electrical safety. The qualified electrical testing laboratories play an important role in the electrical safety system because their work provides the electrical code enforcement community with a strong basis for their approvals. When inspectors are faced with equipment that does not bear such a mark indicating it meets electrical safety criteria and standards, the approval process is more difficult. Many authorities having jurisdiction base their approvals on the use of equipment that has been safety evaluated by a qualified electrical testing organization, such as those mentioned above. This is an essential part of the electrical safety system and is the common inspector approval criteria utilized where approvals of electrical equipment and installations are sought. From the beginning of electrical history, product safety evaluation and testing has been there and has seen the growth and demands paralleled in this industry. It is logical that the electrical safety system depends on the continuous contributions and services provided by qualified electrical testing laboratories and standards writing bodies.

The Role of Inspectors and Inspection Jurisdictions

Being involved in electrical inspection and promoting electrical safety through quality code enforcement is a noble profession. Many of the qualified electrical inspectors in the business today have evolved from being qualified electrical workers to becoming qualified electrical inspectors. Their contributions to the electrical safety that society enjoys today are taken for granted and expected.

There is no room for complacency when it comes to safe electrical installations. The role of the inspector is vital to the industry and as this industry progresses to include more and more advanced technologies and methods of electrical power distribution, the importance of the electrical inspector and his or her role are self-evident.

The responsibilities of electrical inspectors are focused on safety. That’s why they have chosen that career path. The service they contribute helps people. It is important to recognize that those that are knowledgeable about the electrical field understand the hazards electricity can bring to persons and property if it is not properly installed. Inspectors have a serious responsibility and the consequences of not fulfilling those obligations can be severe. So how important is the role of electrical inspector to the electrical safety system? It is extremely important, yet immeasurable. No one can place a dollar amount on the value of the job the inspector does; but examine the many cases where safety is not put first and the results are property losses and injuries and death. How essential are the services provided by electrical and other construction code inspectors? The answer rests with the consumer. The public wants electrical systems to provide quality service without interruption, and they just expect it to be safe. Therefore, the role and services of the electrical inspector are equally as essential as the visible services and work of the fire and rescue teams and the law enforcement departments. They are unsung heroes and their work is as essential today as it was back in time when society first started working with this powerful force.

IAEI Focus on Electrical Safety

IAEI is committed to electrical safety and the role of the electrical inspector and has been since long before the official establishment of the organization. IAEI continues to promote the uniform understanding and application of electrical codes and standards to installations and systems. This is an essential element of the electrical safety system. The focus of IAEI has always been on safety, and the value of the electrical inspector has always been in the interest of the association. Our industry would not be where it is today, nor would it be as safe, if it were not for the electrical inspectors and the job they do. Although the electrical inspector might not have the front page publicity of police officers, firefighters, and other emergency response team personnel, they are truly equally as valuable because their work is proactively resulting in electrical safety for society in general and, more specifically, for families and the way of life we’ve come to expect.

These dedicated members of the electrical field don’t expect recognition for what they do; they have chosen this career path because in their hearts they know and understand the importance and the need. Electrical code enforcement officials are necessary and the value they provide to society is more than just evident, it is undeniably essential.


Read more by Michael Johnston

Tags:  Featured  November-December 2006 

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Electrical Inspectors

Posted By David Young, Wednesday, November 01, 2006
Updated: Sunday, February 10, 2013

Two readers have e-mailed me with the question, "Is there a test I can take to become a certified National Electrical Safety Code‚ (NESC‚) inspector?” The short answer is, no. There are no such tests for the NESC‚ because certification as a NESC inspector does not exist. That doesn’t mean there are no qualified NESC inspectors. Let me explain.

Why do we need inspectors?

In Delaware, we consider electrical inspectors to be very important in protecting the property owners from property damage and the public from electrical hazards. Let’s face it: the people who design and install electrical facilities often screw up. In Delaware, every new or upgraded residential, commercial, and industrial building must pass inspection before a certificate of occupancy is issued. The electrical inspectors, who review the drawings and inspect the installation, catch a lot of the violations and hazards.

By law in most states, outside electrical facilities owned by electric utilities have to comply with the National Electrical Safety Code. The people who design and construct these facilities often screw up and because the facilities are outside, the condition of the facilities deteriorates. Both create hazards to the public.

Hazards are also created by field condition changes. For example, the homeowner installs a swimming pool under the aerial electrical service to the house. A sign is installed under and too close to utility lines. A fixed bridge over a river is replaced by a drawbridge to allow sailboats to go upstream under a power line crossing that was not designed for sailboats. A building is constructed too close to existing power lines.

In some cases, a building inspector should have caught these changes and disapproved the installation or notified the utility. The NESC‚ in Rule 214A requires all new facilities to comply with NESC‚ when placed in service and existing facilities to be inspected "at such intervals as experience has shown to be necessary.” Most utilities in the U.S. do not have inspectors dedicated to inspecting new installations. They assume their design engineers and construction personnel do not make mistakes and they rely upon these people to perform the inspection to insure compliance. As to facility deterioration, most utilities only inspect their poles for ground line deterioration. They rely on their field personnel to catch other deteriorations and field condition changes. Most utilities only use dedicated inspectors after someone gets killed or injured. The inspector is usually called upon to determine if the installation involved with the accident was in compliance with the NESC at the time of the accident.

How can one become a certified electrical inspector?

Here in Delaware, a person wanting to be a state-certifiedNational Electrical Codeinspector must have at least seven years’ experience as an electrician and must pass three tests. I understand that a person must be an expert on the NEC‚ in order to pass the tests. Inspector certification varies state to state.

To be recognized in a court of law as a qualified NESC inspector, one must prove he is an expert on the NESC‚ and prove he has extensive experience inspecting electrical facilities. Since inspection of aerial electrical facilities usually involves taking very accurate measurements of clearances, one must also show proof of extensive experience taking such measurements.

NESC expert

To become an expert in anything, one must obtain a high degree of skill or knowledge and understanding of that subject. The NESC is not easy to understand. Unlike the NEC‚ most of the NESC is directed toward the engineers who design the facilities. I’m not saying you have to be an engineer to understand the NESC‚ but it helps. The NESC rules often tell us how safe something must be, but do not tell us how to build it to make it that safe. For example, many of the NESC rules require some conductors and equipment to be "effectively grounded.” In the definition section, the NESC defines effectively grounded as "Intentionally connected to earth through a ground connection or connections of sufficient low impedance and having sufficient current-carrying capacity to limit the buildup of voltages to levels below that which may result in undue hazard to persons or connected equipment.” I’d say that if something is effectively grounded it is completely safe. So how does one design the facilities to insure that something is effectively grounded when the NESC does not tell you what is "sufficient low impedance” or "sufficient current-carrying capacity.” It also does not tell you what voltage levels "may result in undue hazard to persons or connected equipment.” If someone is injured or killed when they touch a conductor that was supposed to be effectively grounded, then the conductor was obviously not effectively grounded.

To answer the question, the engineer must have knowledge of and draw upon other industry standards to meet the requirements of the NESC. For example, IEEE Standard 80 addresses what is undue hazard to persons and how to calculate the hazard magnitude given the ground system impedance. So how does one become an expert on the NESC? In my case, I have been designing electric power distribution facilities to comply with, and teaching all aspects of the NESC for over 34 years. I have also been an active member of the NESC‚ Clearances Subcommittee since 1994 and the NESC Interpretations subcommittee since 1996. How does one gain extensive experience inspecting electrical facilities? In my case, over the past twenty-five years, I have assisted attorneys and claims personnel with over four hundred accidents involving electric power distribution facilities. My assistance usually involved taking clearance measurements, analysis of the measurements, and testifying in the litigation.


Read more by David Young

Tags:  November-December 2006  Other Code 

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What Do the Markings on Circuit Breakers Mean?

Posted By Ed Larsen, Wednesday, November 01, 2006
Updated: Sunday, February 10, 2013

Have you ever been confused about what the markings on circuit breakers mean? Understanding the markings on electrical equipment is a fundamental need to ensure a safe and reliable electrical installation. Circuit breaker marking requirements are established by the requirements found in the NEC and the UL 489 product standard. This article will discuss the most common markings and where they can be found.

The UL 489 product standard for Molded Case Circuit Breakers specifies the information to be marked on circuit breakers and where it is to be located, so let’s discuss what information needs to be marked on the circuit breaker and the location where you will find those markings. Keep in mind the UL® standard specifies minimum requirements. Circuit breaker manufacturers may provide additional information or provide information in a more convenient location.

Photo 1. Markings visible with trims or covers in place

Markings Visible without Removing Trims or Covers

UL 489 requires that some markings be visible without removing trims or covers. This location is typically referred to as the handle escutcheon (see photo 1).

Markings Visible with Trims or Covers Removed


Photo 2. Markings visible with trims or covers removed

UL 489 requires other markings be visible on an installed circuit breaker with trims or covers removed. This location is typically referred to as the face of the circuit breaker (see photos 2, 3, 4).

Other markings which should be visible with trims or covers removed are:


Photo 3. Markings visible with trims or covers removed

Independent trip –

Multi-pole circuit breakers are constructed with either a common trip, where all poles are mechanically tripped when one of the poles trips, or an independent trip construction where only the pole that is involved with the overcurrent condition trips. If a 2-pole circuit breaker does not have an internal common trip feature, then it must be marked "Independent Trip” or "No Common Trip.” NEC 240.20(B) is the foundational requirement for a common trip function in a circuit breaker; however, it also goes on to explain where independent trip is permitted.

For Replacement Use Only not-CTL –The Class CTL (circuit limiting) panelboard has only been in existence for about 25 years, even though the lighting and appliance branch circuit panelboard has been in the NEC for decades. CTL panelboards have a rejection means designed to reject more than the appropriate number of circuit breakers that can be installed in the panel. The marking "For replacement Use Only Not CTL Assemblies” means that the circuit breaker does not have CTL rejection provisions and is intended for replacement in older equipment pre-dating the CTL requirements for circuit breakers and panelboards. Circuit breakers with this designation should not be installed in a panelboard marked "Class CTL Panelboard” since that would be a violation of the listing of the assembly [NEC 110.3(B)].

Markings Found in Other Locations

The markings we will discuss below may appear in any location except the back of the circuit breaker. These markings include:

40°C –This marking indicates the maximum ambient temperature in which the circuit breaker can be applied at its marked ampere rating without rerating the ampacity of the circuit breaker. This marking is required for thermal-magnetic circuit breakers and is optional for electronic trip circuit breakers unless they are only suitable for a 25°C ambient, in which case they must be marked 25°C. When the ambient temperature rises above 40°C, the designer may need to consult the manufacturer to obtain rerating information (see item 4 in photo 3).

Class CTL –Circuit breakers marked Class CTL have a rejection means designed into the circuit breaker. Class CTL panelboards or assemblies, in conjunction with Class CTL circuit breakers, prevent more circuit breaker poles from being installed than the number for which the equipment is rated.

HACR type –This marking indicates the circuit breaker is suitable for use with the group motor installations typically found in heating, air conditioning and refrigeration equipment. TheNEC2005 no longer has this marking requirement. The electrical industry determined that circuit breakers are considered suitable for use with such equipment without any further testing, therefore, the HACR marking is no longer required on air conditioning and refrigeration equipment or on circuit breakers for use in these applications. The requirement for this marking has also been removed from the UL 1995 product standard for HVAC equipment (see item 3 in photo 1).

Maximum wire size –Circuit breakers are typically marked with a wire range, however that marking is not mandatory. If the circuit breaker cannot accept the next larger wire size required for the ampere rating, then the maximum wire size must be marked in any location except the back (see item 5 in photo 3).

Separately shipped connectors –If connectors are not factory installed on a circuit breaker, then it must be marked with the proper connectors or terminal kits required in any location except the back (see item 8 in photo 3).

Ground-Fault Protection for People

The GFCI function, as part of a circuit breaker, provides ground-fault protection for people and has a number of unique marking and instruction requirements.

Test function –The GFCI has a test function that requires action upon installation and on a monthly basis. GFCI circuit breakers must have a test button or switch that must be labeled in a location accessible without removing trims or covers in order to facilitate monthly testing.

"Class A” marking –A "Class A” ground-fault device is intended to protect people. The Class A marking indicates that the trip threshold of the GFCI is between 4 mA and 6 mA. This marking may be in any location except the back.

Instructions –All GFCI circuit breakers must include instructions for the installer plus instructions on the use of the test function. A hangtag or self-adhesive label must also be provided, instructing the user to test the GFCI at least monthly. Inspectors should check to see that the tag or label has been properly installed.

Ground-Fault Protection for Equipment

Circuit breakers may also include a ground-fault protection for equipment (GFPE) function that, like GFCIs, has a number of unique marking and instruction requirements.

Test function –GFPE circuit breakers may have a test button or switch that may be labeled in a location accessible without removing trims or covers in order to facilitate testing.

Trip level –GFPE circuit breakers must be marked with their trip threshold in milliamperes in a location accessible without removing trims or covers.

Instructions –All GFPE circuit breakers must include instructions for the installer.

Arc-Fault Protection

Circuit breakers may also include arc-fault protection (AFCI) that, like GFCIs, also has a number of unique marking and instruction requirements.

Device identification –AFCIs must also be identified appropriately. Branch/feeder or Combination type AFCIs must be so marked in a location visible when the trims or covers are removed. This is an important marking to note as we move into 2008, asNEC-2005 requires Combination AFCIs in bedrooms effective January 1, 2008 (NEC 210.12).

Test function –AFCI circuit breakers must have a test button or switch that must be labeled in a location accessible without removing trims or covers in order to facilitate testing.

Instructions –All AFCI circuit breakers must include instructions for the installer.

Circuit Breaker Markings Ensure a Safe Electrical Installation


Photo 4. Special marking

So why are all of these markings on circuit breakers? Without them, it would be nearly impossible to install or inspect an installation for the appropriate performance ratings and fundamental electrical connections. When designing or completing an installation, key items to review are:

1. Are the voltage, continuous current, and interrupting ratings appropriate for the application?

2. Does the application require SWD or HID ratings?

3. Is the wire type and size appropriate for the circuit breaker?

4. Is the circuit breaker suitable for the equipment in which it is installed? Have other protective functions such as GFCI or AFCI been provided as required by the NEC?

5. Is the temperature rating of the circuit breaker suitable for the application?

The UL Marking Guide for Molded Case Circuit Breakers is a valuable resource to understand circuit breaker markings that may further explain these and other markings in detail. If you have questions about CB markings not answered here, consult the Marking Guide or the manufacturer to assist in an NEC-compliant installation.


Read more by Ed Larsen

Tags:  Featured  November-December 2006 

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Temporary Services – an anything goes situation?

Posted By Michael Weitzel, Wednesday, November 01, 2006
Updated: Sunday, February 10, 2013

In most areas of the country, building construction is booming, and there is a huge need for and use of temporary construction power. As electrical inspectors and installers in the field, we either inspect, install, or otherwise work with these types of installations frequently, if not daily. That being the case, it can be easy to become too comfortable with electrical equipment that is commonplace and all around us. We may often be a little complacent regarding temporary electrical power. Installations with compromised Code requirements would never be allowed, but often are accepted in temporary service installations for expediency, because "That’s the way we’ve always done it,” or because others aren’t addressing the issue, or even because of the attitude that is prevalent in many minds in the construction trades — It’s only temporary! Keep your shirt on! Or as our Aussie friends say, No worries!

Temporary services can create challenges for installers and inspectors. This article focuses on temporary services, temporary service equipment short-circuit current ratings, common Code violations that may be found in temporary service installations, and the need for comprehensive inspections every time a service is installed, whether temporary or permanent.


Photo 1. Typical Temporary Service
 

Figure 1. Service equipment installed close to a transformer with large kVA capacities require suitable equipment short-circuit interrupting ratings.

Common Code violations indicate that there is somewhat of a lax attitude toward temporary power services. Hazards exist every day on construction sites. Let’s not add to the problem! Some perils are obvious, such as the possibility of a fall from an upper level of a high-rise building. Others may be just as real, but not as apparent. One such item is short-circuit protection and ratings of temporary electrical service equipment. The classic example is a temporary service rated 200 amperes or less, that is supplied from a 500 kVA or larger transformer and located immediately next to the service equipment, with a very short length of service conductor (see figure 1).


Photo 2. Temporary service

In this case, a ground fault in the electrical service equipment could result in high levels of fault current flowing into equipment that most often does not have a sufficient interrupting rating, possibly causing an explosion and/or damaging life and property. This type of installation would not comply with NEC 110.9 and 110.10, yet is commonplace. Many types of accidents occur on construction sites. A ground fault could easily occur when a temporary service is struck and knocked down by construction equipment. Overhead conductors may be snagged by a truck or forklift mast, etc., even if all Code minimum clearances were complied with. But not to worry; after all, it’s only temporary, right?

This is an issue, however, that many jurisdictions have not addressed. Again, it appears that there is an attitude of complacency. Is that a good reason not to require at least the minimum level of code-compliance? Some may ask, Where’s the ‘body count’? Remember that not every Code rule exists because of a death or injury, though that does get people’s attention, at least for a while. The rule may be totally appropriate, and necessary to a safe installation. Another concern is that requiring electrical equipment for temporary services to have adequate interrupting ratings would result in an uproar from the construction community, because of the additional cost for equipment with higher fault-current ratings. The minimum requirements of the Code apply whether the service is temporary or not. Appropriately rated equipment can be added, and the job can be done without a huge expense, though you are practically guaranteed to hear, We’ve never had to do that before! That’s true in many cases. But electrical systems and installations have improved greatly over the years for safety and usability, as has the NEC; and as an industry, we are learning all the time, or should be, as our trade is constantly changing. It should be noted that the calculations found in figure 2 are based on an infinite current supply from the serving utility.


Figure 2. Calculations based on an infinite current supply from the serving utility

The Code does not place any less importance on proper short-circuit protection and adequate ampere interrupting capacity of overcurrent protective devices and equipment ratings for temporary services as compared to permanent service installations. The question is, do we?

It is important to remember that chapters 1 through 4 of the NEC apply to temporary services. Section 590.2(A) states that "Except as specifically modified in this article, all other requirements of this Code for permanent wiring shall apply to temporary wiring installations.”


Table 1. Common code violations found in temporary service installations

Because of the heavy workload that many jurisdictions have, it’s often easy to feel rushed or get in a hurry when inspecting temporary services. The thought may prevail, It’s only temporary, it’s not a big deal. Such assumptions are risky, and can be dangerous. The need to inspect carefully each temporary service every time it is placed on a jobsite cannot be overlooked, even if you have previously inspected it, perhaps many times before. Even if the installation looks safe, there could be hidden hazards that may not be apparent. Also, things can happen to the equipment between the time it was first inspected and when it is used again on the next jobsite.


Table 1, continued

In some jurisdictions, electric utilities may provide — and their line crews may also install — temporary services. In such cases, it is possible that no electrical inspection is performed or required, or the persons inspecting may be professionals in their field but not trained electrical inspectors that understand the hazards and know what to look for to assure a safe installation that is code-compliant. The question is, are these types of installations truly safe?

If temporary construction power installations are within your responsibility, please consider the following suggestions: Good working relationships are important, but it’s wise not to make assumptions that because you know the contractor and/or may have inspected this particular piece of equipment before, that the equipment is still safe and meets at least the minimum Code standards. There may be hidden concerns or damage that you or they have no idea exists. Damage to electrical equipment can easily occur, for example, where the temporary power pole is removed by a backhoe that pulled it out of the earth. In the process, the service grounded (neutral) conductor was pulled on very hard, which destroyed the neutral and ground bar in the service equipment. In other cases, the service ungrounded conductors were completely pulled out of their terminations in the service equipment or meter base, or made very loose.

Another example is supply-side grounded and ungrounded conductors being connected to the wrong terminals of service equipment, which if energized will give off enough fireworks to remind you of the 4th of July! Many temporary service installations are installed by non-electrical personnel that often don’t realize what is needed or required for electrical safety. All they know is that "the boss said to put the pole in” and, by golly, that’s what they’re doing. And, usually, all the builder or owner is concerned about with his service is, How quick can you get this thing approved, and get me my power? Sound like the real world to you? It is common in field construction trades to have varying skill levels and awareness of electrical safety. Many non-electrical construction trades people really don’t have a good idea of what is electrically safe or not, and what items — especially subtle errors — may place their safety and others around them at risk.

OK, at this point you may be saying, Hey, give me a break! If there were conductors pulled out of lugs, I’d catch that in a heartbeat. Yes, you probably would catch the obvious stuff, but what about those more subtle things that can be deadly if ignored or bypassed because you have a huge inspection schedule, a limited amount of time, and you promised contractors that you’d be at their jobsites soon but you’re already running late? Most of us have "been there, and done that.” We enjoy being out in the field, being a part of what’s going on, and helping people. However, when it comes to safety, and signing our name to an inspection approval or citation, we need to take the time even when we don’t think we have it. Every installation is important, even if it’s a temporary one.

I have personally experienced situations where a construction laborer moved the ground rod from one temporary service that was approved and energized by the utility, to another lot location in the subdivision for a new temporary service. Hey, the power is on, it must be okay! The man didn’t do it maliciously, he simply had no idea of the importance of grounding, or how a lack of it could affect his own safety! Installers have the responsibility to comply with NEC 110.7, Insulation Integrity, and assure that their electrical installation is free from short circuits and ground faults. Installers also must continue to be encouraged to look over their work and check it as needed before calling it in for inspection. As electrical inspectors, we visibly inspect the installation, drawing on our experience, training, and Code knowledge for compliance with adopted codes and standards. Quality electrical inspections are a vital part of safety for persons and property arising from the use of electricity.

One proposal for NEC-2008 intends to improve safety on construction sites. Proposal #13-11 creates new Section 445.20, which will require GFCI protection for all 125 and 125/250-volt, single-phase, 15-, 20-, and 30-ampere receptacle outlets that are part of portable electric generators. It may surprise you that this has not been previously required in the Code, but it’s true.

Table 1 provides some common Code violations often found on temporary services. This is intended to be a useful guideline, but not an all inclusive checklist. Others items may apply to specific installations or geographical areas.

Installing a temporary service on a jobsite means that many more inspections will follow on the same site. As subsequent inspections are made, changes to the temporary service installation that had previously been approved may develop because of damage or abuse. Finding support posts knocked over, grounding electrode conductors cut in half or damaged, or other types of physical damage is not uncommon. The electrical permit holder has responsibility for the safety of the temporary service installation. However, as we become aware of unsafe situations regarding the temporary service electrical equipment, we need to alert the permit holder as soon as possible.

In summary, we have focused on temporary services, their equipment short-circuit current ratings, common Code violations found in temporary service installations, and the need for comprehensive inspections every time a temporary service is installed.

There is an apparent need in the field to be more aware of electrical safety for temporary electrical service installations. In general, the only difference between a temporary electrical service and a permanent one is the length of time that it exists. Making sure that service equipment has the proper ratings for the short-circuit current available at the equipment, and that every temporary service installation is thoroughly inspected will go a long way toward electrical safety.


Read more by Michael Weitzel

Tags:  Featured  November-December 2006 

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Electrified Truck Parking Space Equipment

Posted By Ron Janikowski, Wednesday, November 01, 2006
Updated: Sunday, February 10, 2013

Each code cycle, members of the code-making panels have the opportunity to review countless code proposals. Every now and then, a proposal to develop a new article is received. The Technical Correlating Committee (TCC) then has to determine its merits and assign a code panel, based on their assigned Code sections, to review and select which chapter in the Code would be the appropriate location for the new article. This year was no exception. Panel 12 was assigned to review a proposed new Article 626, Electrified Truck Parking Space Equipment As a principal member of CMP-12 and member of the task group assigned to this new article, I was excited to work on an article that could potentially revolutionize the long-haul commercial trucking industry and help reduce our dependence on foreign oil.

Photo 1. Shurepower stanchion-mounted pedestal

Background


Figure 1. States with idling regulations

By way of introduction to the members of CMP-12, this code proposal was developed by the Truck Stop Electrification (TSE) Committee of the National Electric Transportation Infrastructure Working Council (IWC), sponsored by the Electric Power Research Institute (EPRI). The TSE Committee is a multi-industry group of professional volunteers, involving truck manufacturers, TSE designers and implementers, component manufacturers, utilities, and members of the National Association of Truck Stop Operators, Society of Automotive Engineers (SAE), Environmental Protection Agency, Department of Energy, Department of Defense, Institute of Electrical and Electronics Engineers (IEEE), Electric Power Research Institute (EPRI), and others, working together to develop the TSE infrastructure.

The panel was asked to consider the following statistics:

  • U.S. DOT hours-of-service (HOS) regulations, revised in August 2005, require long-haul drivers to rest a minimum of 10 hours after driving 11 hours. The approximately 1.4 million heavy-duty long-haul trucks on the road typically idle 10–12 hours per night, 300 nights per year.
  • Trucks emit over 0.3 tons of nitrogen oxides and 21 tons of carbon dioxide each year while burning 1 to 1.3 gallons of fuel for each hour of idling.
  • Idling trucks collectively burn 3.7 billion gallons of diesel fuel annually at a cost of more than one trillion dollars to the industry. That number increases as the cost of fuel increases. Other areas of concern are engine wear and tear and noise.

Photo 2. IdleAire's cab control center

Over the past several years, the attention of regulatory agencies and environmental groups has focused on reducing truck idling. Developing a standardized, safe and efficient means of reducing fuel consumption and emissions has been the goal. As of today, more than twenty states and cities have already adopted legislation to reduce the number of hours a truck idles.

Today, approximately 500,000 truck parking sites exist in the United States, with an additional 200,000 sites in non-dedicated parking areas and loading sites around the country. Less than one percent of these sites now provide any electrified parking space equipment.


Figure 2. Stop idling!

Stiffer 2007 and 2010 emission standards for trucks also enhance the need to develop a means to reduce idle time while still providing for the "creature comfort” services.

The Challenge


Photo 3. Example of Shurepower equipment

The challenge is to develop specific electrical code rules that address the very specialized needs of trucks as they stop for their required downtime and connect to electrified truck parking space equipment. Truck stop electrification (TSE) equipment must provide an alternative for providing heat, A/C, and electrical power in the truck cab with the engine off. Once the connectivity issues of standardization, consistency and safety are in the Code, truck manufacturers can start to supply on-board standardized electrical equipment to mate with the off-board equipment the NEC governs. Article 626 will outline standard NEMA configurations, wiring methods and demand factors for the geographical areas of the country to make it economically viable to users. The infrastructure will be a major undertaking but federal grants and funds are available.


Figure 3. Anticipated growth in shorepower capable trucks

Another challenge is the initial hesitance of truckers to change their habits. Education, regulations and fleet owners can help change habits.

Future challenges have also been identified as the ability to power the truck refrigeration units (TRU). Approximately 10 percent of the trucking fleet has TRU units. Article 626 will be a good starting point as the industry comes on board with standard configurations. Future code proposals will tweak the code as new technology and standardization of the OEMs come on-board. It has also been discussed to have NAFTA-wide coverage for US, Canada and Mexico.


Photo 4. TSE hookup

Where We Are Today

To date, two companies have taken the lead in engineering and installation of TSE sites. IdleAire1 and Shurepower2 have existing installations currently open, with other sites under construction. IdleAire uses an overhead gantry system to supply HVAC, phone, electric, CATV, and internet services to the truck cab. Shurepower delivers reliable single-phase 220 and 120-VAC power along with high-speed Internet, phone and cable TV services through an all-weather stanchion-mounted underground power pedestals. IdleAire has 225,000 parking spaces under contract throughout the southern tier of states. Shurepower has installations throughout the state of New York, with other installations in the planning stages. The anticipated growth in shorepower capable trucks is expected to skyrocket to more than 500,000 units on the road by the year 2014. As on-board systems become the standard and additional states regulate idle time, the infrastructure will have to keep up with demand. The southern tier of states will demand more HVAC cooling, with the northern tier of states and possibly Canada requiring infrastructure to provide cab heating and outside receptacle outlets for block/fuel heaters. The trucking industry in today’s digital age mandates that drivers have the capacity to communicate with dispatch through not only telephone but also high speed Internet capable interfaces. Several sites have wireless Internet hot spots. These services are currently available by scanning a credit card at the site or pay/control kiosk on the grounds. Current costs are very favorable compared to the cost of fuel.


Photo 5. Example of Shurepower equipment installation


Figure 4. Loading dock equipped with TSE hookup

Conclusion

It has been exciting to work on a new Code article that will help preserve and clean up our environment as well as reduce our dependence on foreign oil. This article, which was accepted in principle at ROP meetings last December, is still a work in progress. The task group responsible for the final document has had several conference calls as well as one on-site meeting in Atlanta, Georgia, to visit existing and new TSE sites. As of this date, no standardized provisions for truck refrigeration units (TRU) exist. As the code cycle proceeds, TSE providers will have some guidance to provide the correct electrical systems to connect the TRU units.


1 IdleAire Technologies Corporation, 410 N. Cedar Bluff Road, Suite 200, Knoxville, TN 37923

2 Shurepower, LLC, 153 Brook Road, Rome, New York 13441


Read more by Ron Janikowski

Tags:  Featured  November-December 2006 

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Electrical Safety In Health Care Facilities, Canadian Perspective – What Should We Know?

Posted By Ark Tsisserev, Wednesday, November 01, 2006
Updated: Sunday, February 10, 2013

Which areas of a health care facility electrical system must be tested for voltage difference between ground points, for ground return path voltage rise — in grounded systems or for test of impedance to ground — in isolated systems? Which loads of an electrical system in a health care facility are considered to be essential system loads and what kind of the power supply must be provided to these loads?

These questions are often asked by the electrical designers and contractors. The answer may be found in a combination of the following documents: the National Building Code of Canada (NBCC), the Canadian Electrical Code (CEC) and the CSA Standard Z32 "Electrical Safety and Essential Electrical Systems in Health Care Facilities”.

Article 3.2.7.6. of the NBCC states that an emergency electrical power supply system for emergency equipment required by the Building Code (for elevators, smoke control and smoke venting fans, fire pumps) must be installed in conformance with CAN/CSA-Z32.

Z32 defines emergency electrical power supply system as "one or more in-house electrical generator sets intended to be available if all other supplies fail, and capable of supplying all of the essential loads”.

Essential electrical system is also defined by this standard. It means "an electrical system that has the capacity of restoring and sustaining a supply of electrical energy to special loads if the normal supply of energy is lost.”
Section 6 of Z32 provides requirements for essential electrical systems and explains that the essential system consists of the emergency equipment required by the NBCC (elevators, smoke control and smoke venting fans, fire pumps) and of special loads that are intended to provide effective and safe patient care in a health care facility.

Table 8 of Z32 classifies essential system loads and branches and their intended performance (vital, delayed vital or conditional) for a specific type of patient care.

So, now some of our questions posed at the outset — appear to be answered. But what about a difference in electrical installations between hospitals and, let’s say, doctors’ offices? Section 24 of the CEC helps to clarify this issue. Until the 2002 edition of the CEC had been developed, Section 24 was limited only to electrical installation requirements in patient care areas of hospitals.

However, Scope of Section 24 in the 19th edition of the CEC, Part I (2002 edition) had been expanded to cover installations within patient care areas of "health care facilities”. Respectively, definition of hospital has been deleted from Rule 24-002 "Special Terminology” and a new definition health care facility has been added.

This change from hospital(s) to health care facility(ies) had been made throughout Section 24 and Appendix B, to harmonize Section 24 with the CAN/CSA-Z32. CSA standard Z32 further subdivides health care facilities into three separate classes as follows:

Health care facility, Class A – a hospital, so designated by Canada or one of its Provinces or Territories, where patients are accommodated on the basis of medical need and are provided with continuing medical care and supporting diagnostic and therapeutic services;

Health care facility, Class B – a facility where residents, as a result of physical or mental disabilities, are unable to function independently and are accommodated due to a need for daily care by health care professionals;
Health care facility, Class C – a facility where ambulatory patients are accommodated on the basis of medical need and are provided with supportive, diagnostic, and treatment services.

Z32 provides a variety of examples of such health care facilities, and in addition to hospitals these examples include surgical, outpatient and doctor’s clinics, dentist offices, psychiatric and rehabilitation facilities.

The impact on installations is that facilities that were previously not included by Section 24 rules now have to follow the Patient Care Areas requirements (Rules 24-100 to 24-114) which have very specific criteria for circuits, bonding, receptacles and other equipment.

Thus, in our example above, electrical installations in a patient care are of a large teaching hospital have be similar to the installations in a typical doctor’s office that is located in a unit of an office building. Of course, such installation requirements for a patient care area occupied by a psychiatrist or a massage therapist may appear to be very drastic, as offices of such health care practitioners may be established in a typical unit of a commercial building where the previous tenant was a travel agent or an alteration shop and where special needs for receptacles, bonding, etc., have not previously existed.

It should be understood that relevant Rules of Section 24 are intended to apply to the installation of electrical wiring and equipment within patient care areas of those types of health care facilities where permanently or cord connected electro-medical equipment is used for the purpose of intentional contact at a patient’s skin surface or internally during the patient’s treatment, diagnostics or monitoring.

The inspection authority may require involvement of the professional electrical engineer at the permit and installation stages in order to ascertain a specific class of a health care facility and conditions of use of the electro-medical equipment and to supervise tests referenced in Appendix B Note on rules 24-104(1) and 24-112 of the Code.

Some jurisdictions provide additional clarifications to the electrical contractors on application of the requirements of Section 24 of the CEC.

City of Vancouver, for example, has developed a special declaration form for completion by a professional electrical engineer, where a statement is made that permanently or cord connected electro-medical equipment is not used for the purpose of intentional contact at a patient’s skin surface or internally during the patient’s treatment, diagnostics or monitoring; or that there will clearly be no danger from use of the electro-medical equipment when a typical commercial unit is intended to be occupied as a doctor’s office, etc., where a patient care area as defined by Section 24 of the CEC will exist.

However, where the installation of electrical wiring and equipment is done in patient areas of those types of health care facilities where permanently or cord connected electro-medical equipment is used for the purpose of intentional contact at a patient’s skin surface or internally during the patient’s treatment, diagnostics or monitoring, then all applicable provisions of Section 24 of the CE Code must be met, and all test requirements for voltage drop test, voltage difference between ground points test, impedance to ground test, etc., as mandated by Section 5 of Z32 must be met.

And as usual, authorities having jurisdiction must be consulted by designers and contractors contemplating electrical installations in patient care areas of health care facilities.


Read more by Ark Tsisserev

Tags:  Canadian Perspective  November-December 2006 

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Some 2006 Canadian Electrical Code Changes

Posted By Leslie Stoch, Wednesday, November 01, 2006
Updated: Sunday, February 10, 2013

The 2006 Canadian Electrical Code makes a number of changes from 2002. In this article, we will visit and discuss a few changes, take a look at why they became necessary, and in some cases, review their application.

Rule 32-200(b) Fire Pump Conductors

Fire pump wiring must be protected against fire exposure to provide continued operation of the fire pumps during a fire. Obviously, you don’t want a fire pump to stop working in the midst of a fire. Appendix B references the NFPA20 standard which offers additional details on the protection of circuits feeding fire pumps against fire damage. The reasons are fairly obvious.

Appendix B also offers some examples on how to satisfy the requirements of Rule 32-200(b) for protecting fire pump circuits by using heat-resistant wiring or enclosing the wiring in fire-resistant building materials. The Appendix B guideline includes:

  • installing the fire pump conductors in mineral-insulated cable;
  • installing fire pump conductors in conduit surrounded by a minimum 50 mm of concrete; or
  • installing the fire pump conductors in a shaft that provides a minimum one hour fire separation from the rest of the building.

Rule 10-302(a) and (b) Underground Service

An electrical utility’s metal-covered (metallic-sheathed or metal armoured) cable or metal conduit need not be bonded to ground at a customer’s premises if the cables or conduit are isolated from the customer’s internal metallic conduit or piping.

The reason for this rule change: Some electrical utilities prefer to isolate one end of metal-covered cable or metal conduit from ground at the customer’s location so as to minimize corrosion due to:

  • circulating currents induced by large single-conductor loads;
  • contacts and galvanic corrosion between dissimilar meals; or
  • improper operation of cathodic protection systems installed to protect the underground cables or conduit against corrosion.

Rule 36-006(1)(e)
Warning Notices

A warning sign carrying the words "Danger – High Voltage” or ”Danger —– V” must be displayed on every substation fence to be sure they are not overlooked:

  • next to the locks on all outdoor substation gates;
  • at all corners of the substation fence; and
  • the signs must not be spaced more than 15 m apart.

The reason for this rule change —to make sure that anyone, and in particular, untrained and unqualified people become well aware that the inside of the substation fence contains serious personal hazards by ensuring that the warning signs are available when approaching the station and in the most obvious places.

Rule 26-700(11)
General (Receptacles)

Any receptacle within 1.5 m of a sink, bathtub or shower stall must be connected with a circuit protected by a Class A ground fault current interrupter. You will recall that a Class A GFCI will trip and disconnect the electrical supply in the event of a ground fault of 5 milliamperes or higher. The only exceptions to this rule are stationary appliances (such as clothes washing machine), and so located that the receptacle would be inaccessible for general use.

The reason for this change—to prevent electrical shock hazards when receptacles are located in close proximity of well-grounded metal. We are most vulnerable to electric shock when we are well-grounded, especially when in contact with the grounded metal of water piping connected to sinks, bathtubs and shower stalls. It should be noted that in patient care areas of hospitals, Rule 24-106(3) Receptacles in Basic Care Areas now has an identical requirement for receptacles in a washroom and within 1.5 m of a wash basin.

Rule 26-724(4) Branch Circuits for Single Dwellings

An outdoor receptacle accessible from grade level must now be supplied from a dedicated branch circuit to ensure that operating an electric lawn mower or other outdoor electrical appliances or tools will not trip the circuits inside the dwelling. I’m sure everyone has suffered the frustration of a power outage while on the computer or finding the beer fridge out of service.

Rule 10-806(4) Installation of System Grounding Conductors

This rule change will affect you if you’re in the habit of protecting system grounding conductors using iron or steel. Magnetic materials (iron or steel pipe or conduit) used for mechanical protection of grounding conductors must now be bonded to the conduit or pipe at both ends.

The reason, when fault current flows in the system grounding conductor, unless a portion of the ground fault current is permitted to pass through the conduit, the magnetic material will have a "choking” affect on the grounding conductor, increasing the impedance of the grounding conductor. This reduces the flow of ground fault current, causing a delay in the operation of fuses or circuit-breakers to remove the fault.

As with past articles, you should always check with the local electrical inspection authority for a more precise interpretation of any of the above.


Read more by Leslie Stoch

Tags:  Canadian Code  November-December 2006 

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The Dream

Posted By Wayne Lilly, Wednesday, November 01, 2006
Updated: Sunday, February 10, 2013

By the time this editorial appears in the IAEI News my year as international president will almost be over. As most would do at this time, I am reflective about my years with IAEI and about IAEI then and now. It is said that the longest journey begins with a single step. Looking back over the years, we can trace the steps IAEI has taken to be where it is today. The journey began as a dream that someone had about an organization dedicated to electrical safety and education that made room for all the members of the electrical industry family. It leads from that first dream to a membership of more than 17,000 spread around the globe. It leads from a small, donated office space to a modern, two-story building with several offices, meeting rooms, state-of-the-art training facilities, and shipping, receiving and warehouse areas. It leads from typewriters to desktop computers to laptops. It leads from black and white publications to state-of-the-art, award-winning multi-colored publications. The journey is similar in many ways to the journey each of us has taken. It has many high and low places. It seems to meander at times with neither clear direction nor purpose. During these times, the road has many side trails that lead to dead ends. Steps can be seen that retrace over themselves. At other times, the road seems smooth and straight. The direction and purpose are crystal clear and it seems that cruise control was engaged with no radar in sight.

Knowing where we have been and where we are now are essential to preparing for the future. If IAEI is to exist in the future, we must study and learn from the past and the present. Although there have been some times in our history where we have been stagnant, generally we have been an organization constantly moving forward. We are ever seeking to expand our opportunities to offer education and services to our brother and sister members and others. We now stand on solid ground ready to spring forward into the future with a membership dedicated to a set of common goals, with an excellent financial status, with industry leading publications, with topnotch employees and with representatives to other organizations that are as good or better than any found within the industry. We are ready to take bold strides into the unknown that is tomorrow.

Where does tomorrow lead? We are trying to look into the future and see what is there. Do you sometimes wish you had a crystal ball that would let you peer into the uncertain, mist-covered future and see with clarity what lays hidden there? Or maybe a visit to the Twilight Zone would let you see in bright sunlight what is now covered by deep darkness? Trying to see the future is very much like driving in a heavy fog. You know that there is something out there, but you just can’t quite see it. As you move forward you begin to see dim shapes that become clearer and clearer as you get closer and closer. Sometimes those dim shapes become well-lit highways and other times they become stress in our path. If you decide not to move at all, everything remains hidden within the fog. Going nowhere means you will be passed by those bold enough to move cautiously forward.

Many of us are frightened by what might be just around the next corner and choose to hide our heads in the sand. We are frozen by fear of the future. However, standing still is not an option. If we stand still, we die as an organization. We must continue to move forward. Many of us seem to rush with abandon into the future without any concern for where it might lead us or what we might find there. It seems we are bent on self-destruction. I suspect that most of us find ourselves somewhere between these extremes. We want to know the future, but only the good parts. We want to go forward but ever so slowly so we can see the pitfalls, bumps and trees in the road so we can avoid them. We like to know as much as we can about the next step in the road before we take it.

If there is a tomorrow in the future, time will force us to move toward it. We must ask ourselves a question about this movement. In what direction do we go and how do we get there? Trying to look through the heavy fog that is the future is not easy. Crystal balls do not have a good track record. What we must do is forge together the notions of rushing forward with little or no concern about the consequences of hiding our heads in the sand. The correct path lies between these two. For us to move into the future we must mold these two into one. Doing so will not be easy. The pendulum will swing slightly to one side or the other. At times it will seem that we are too cautious and at other times we are rushing forward with little concern about the consequences. We will always face the question of boldness. Are we too bold or not bold enough?

In my humble opinion, we face a future that is fraught with everything from minor pitfalls to "atomic bombs”. We must constantly be stepping boldly while trying to avoid them. From time to time we will step into a pitfall. We may even set off bomb or two. I believe we have the strength of will and the fortitude to survive. The future will not be easy. It never is. An old proverb says, "Into each life a little rain must fall.” IAEI will certainly face its share of "a little rain.” However, I believe that as long as our eyes are set on the goals of electrical safety, education, support for each other and our fellowman, IAEI will be a strong and active association. We must not let our focus be diverted by petty squabbles or selfish motives nor should we let our ideals be compromised. If we realize that the goals are worth the effort, the race will be won. We must remember the dream that became IAEI and try continually to live it.

The opportunities we will be given in the future will be enormous. They may even be more enormous than the pitfalls and bombs. IAEI will have opportunities to grow into the entire world, to utilize the Internet and other electronic media in ways we cannot even imagine, to forge new partnerships and to advance the safe use of electricity in new and wonderful ways. We will see our working relationship with some old friends go by the wayside and make many new ones. The challenges associated with these opportunities will be difficult. To face those challenges, IAEI must maintain an open mind that is receptive to change and new ideas. It must put the dream that is IAEI into practice.

That original dreamer could not see through the mist-covered future. The dreamer had no idea that IAEI would be where it is today. There was no crystal ball to peer into that would reveal the future. Dreams are only dreams. It takes hard work, dedication, foresight and love of the dream to make a dream a reality. Sometimes, it even takes a little luck. IAEI is where it is today for these reasons. Each of us who are members is sharing in the dream that is IAEI. The duty of each member is to strive to keep the dream alive and flowering. I salute each and every one of you who are working to see the dream remain a reality. IAEI will not survive without you. It has been fortunate to have people who love the dream and work selflessly, with no desire for personal glory, to make IAEI a success.

Doctor Martin Luther King said, "I have a dream.” Because he had that dream and shared it with others, the United States and, in reality, the world was changed. I don’t pretend to equate the dramatic results, grandeur, scope, or need of the dream that is IAEI with the dream that is the civil rights movement. However, there is one thing they both have in common. Like the civil rights movement, the future of IAEI still lies with that original dream. If we continue to believe in and promote the dream that is IAEI, the future of IAEI will be safe. The duty belongs to each one of us. Are you a dreamer? Is IAEI important to you? Do you still believe in the dream? Stand up and do your part! Remember, "United we stand, divided we fall.”


About Wayne Lilly: Wayne Lilly was the 2006 International President.

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The Dream

Posted By Wayne Lilly, Wednesday, November 01, 2006
Updated: Sunday, February 10, 2013

By the time this editorial appears in the IAEI News my year as international president will almost be over. As most would do at this time, I am reflective about my years with IAEI and about IAEI then and now. It is said that the longest journey begins with a single step. Looking back over the years, we can trace the steps IAEI has taken to be where it is today. The journey began as a dream that someone had about an organization dedicated to electrical safety and education that made room for all the members of the electrical industry family. It leads from that first dream to a membership of more than 17,000 spread around the globe. It leads from a small, donated office space to a modern, two-story building with several offices, meeting rooms, state-of-the-art training facilities, and shipping, receiving and warehouse areas. It leads from typewriters to desktop computers to laptops. It leads from black and white publications to state-of-the-art, award-winning multi-colored publications. The journey is similar in many ways to the journey each of us has taken. It has many high and low places. It seems to meander at times with neither clear direction nor purpose. During these times, the road has many side trails that lead to dead ends. Steps can be seen that retrace over themselves. At other times, the road seems smooth and straight. The direction and purpose are crystal clear and it seems that cruise control was engaged with no radar in sight.

Knowing where we have been and where we are now are essential to preparing for the future. If IAEI is to exist in the future, we must study and learn from the past and the present. Although there have been some times in our history where we have been stagnant, generally we have been an organization constantly moving forward. We are ever seeking to expand our opportunities to offer education and services to our brother and sister members and others. We now stand on solid ground ready to spring forward into the future with a membership dedicated to a set of common goals, with an excellent financial status, with industry leading publications, with topnotch employees and with representatives to other organizations that are as good or better than any found within the industry. We are ready to take bold strides into the unknown that is tomorrow.

Where does tomorrow lead? We are trying to look into the future and see what is there. Do you sometimes wish you had a crystal ball that would let you peer into the uncertain, mist-covered future and see with clarity what lays hidden there? Or maybe a visit to the Twilight Zone would let you see in bright sunlight what is now covered by deep darkness? Trying to see the future is very much like driving in a heavy fog. You know that there is something out there, but you just can’t quite see it. As you move forward you begin to see dim shapes that become clearer and clearer as you get closer and closer. Sometimes those dim shapes become well-lit highways and other times they become stress in our path. If you decide not to move at all, everything remains hidden within the fog. Going nowhere means you will be passed by those bold enough to move cautiously forward.

Many of us are frightened by what might be just around the next corner and choose to hide our heads in the sand. We are frozen by fear of the future. However, standing still is not an option. If we stand still, we die as an organization. We must continue to move forward. Many of us seem to rush with abandon into the future without any concern for where it might lead us or what we might find there. It seems we are bent on self-destruction. I suspect that most of us find ourselves somewhere between these extremes. We want to know the future, but only the good parts. We want to go forward but ever so slowly so we can see the pitfalls, bumps and trees in the road so we can avoid them. We like to know as much as we can about the next step in the road before we take it.

If there is a tomorrow in the future, time will force us to move toward it. We must ask ourselves a question about this movement. In what direction do we go and how do we get there? Trying to look through the heavy fog that is the future is not easy. Crystal balls do not have a good track record. What we must do is forge together the notions of rushing forward with little or no concern about the consequences of hiding our heads in the sand. The correct path lies between these two. For us to move into the future we must mold these two into one. Doing so will not be easy. The pendulum will swing slightly to one side or the other. At times it will seem that we are too cautious and at other times we are rushing forward with little concern about the consequences. We will always face the question of boldness. Are we too bold or not bold enough?

In my humble opinion, we face a future that is fraught with everything from minor pitfalls to "atomic bombs”. We must constantly be stepping boldly while trying to avoid them. From time to time we will step into a pitfall. We may even set off bomb or two. I believe we have the strength of will and the fortitude to survive. The future will not be easy. It never is. An old proverb says, "Into each life a little rain must fall.” IAEI will certainly face its share of "a little rain.” However, I believe that as long as our eyes are set on the goals of electrical safety, education, support for each other and our fellowman, IAEI will be a strong and active association. We must not let our focus be diverted by petty squabbles or selfish motives nor should we let our ideals be compromised. If we realize that the goals are worth the effort, the race will be won. We must remember the dream that became IAEI and try continually to live it.

The opportunities we will be given in the future will be enormous. They may even be more enormous than the pitfalls and bombs. IAEI will have opportunities to grow into the entire world, to utilize the Internet and other electronic media in ways we cannot even imagine, to forge new partnerships and to advance the safe use of electricity in new and wonderful ways. We will see our working relationship with some old friends go by the wayside and make many new ones. The challenges associated with these opportunities will be difficult. To face those challenges, IAEI must maintain an open mind that is receptive to change and new ideas. It must put the dream that is IAEI into practice.

That original dreamer could not see through the mist-covered future. The dreamer had no idea that IAEI would be where it is today. There was no crystal ball to peer into that would reveal the future. Dreams are only dreams. It takes hard work, dedication, foresight and love of the dream to make a dream a reality. Sometimes, it even takes a little luck. IAEI is where it is today for these reasons. Each of us who are members is sharing in the dream that is IAEI. The duty of each member is to strive to keep the dream alive and flowering. I salute each and every one of you who are working to see the dream remain a reality. IAEI will not survive without you. It has been fortunate to have people who love the dream and work selflessly, with no desire for personal glory, to make IAEI a success.

Doctor Martin Luther King said, "I have a dream.” Because he had that dream and shared it with others, the United States and, in reality, the world was changed. I don’t pretend to equate the dramatic results, grandeur, scope, or need of the dream that is IAEI with the dream that is the civil rights movement. However, there is one thing they both have in common. Like the civil rights movement, the future of IAEI still lies with that original dream. If we continue to believe in and promote the dream that is IAEI, the future of IAEI will be safe. The duty belongs to each one of us. Are you a dreamer? Is IAEI important to you? Do you still believe in the dream? Stand up and do your part! Remember, "United we stand, divided we fall.”


About Wayne Lilly: Wayne Lilly was the 2006 International President.

This post has not been tagged.

Share |
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