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Testing for Improved Power Distribution Reliability

Those responsible for a facility’s operation hear the same thing over and over again – reduce costs and improve productivity. Much attention has been given to reducing raw material and labor costs, increasing production efficiency, automating processes, and other key areas, but what about the often overlooked cost of an electrical outage? Depending on the type of facility, one outage can paralyze building systems and cost thousands – or even millions – of dollars in lost production, downtime, damage to equipment and product, and possible injury or death to personnel.

OSHA, NEC, NFPA Pieces of the Puzzle

The next time you are near the bulletin board at work, look for the poster that has the words “It’s the Law” and “OSHA” on it. It has probably been hanging there for a very long time but most people never really notice it or seem to read it. Further down on the poster is the statement “each employer shall furnish to each of his employees employment and a place of employment which are free from recognized hazards that are causing or are likely to cause death or serious physical harm to employees. This statement is known as OSHA’s General Duty Clause and is at the heart of linking many of the other standards to OSHA.

Grounding Power Distribution Systems

The NEC contains specific articles that dictate when you shall ground, when you shall not ground, and when you are permitted – but not required – to ground. These code requirements are based on various factors such as whether or not there are connected phase to neutral loads, whether only qualified persons service the installation, and operating voltage levels.

Hazardous Locations

The NEC defines a “Hazardous Location” as a location “where fire or explosion hazards may exist due to flammable gases or vapors, flammable liquids, combustible dust, or ignitable fibers or flyings.” There are 13 articles and 68 pages in the NEC regarding hazardous locations, installation practices and equipment requirements. Understanding what makes a location “hazardous” is the first step in providing a safer electrical system.

Materials that can cause a location to be classified as hazardous range from hydrogen, to grains, coal dust, petroleum products and many others.

Snow Job! Behind the Scenes at a Ski Resort

Every November the snow making equipment at your favorite ski resort is expected to start up flawlessly. The pumps, compressors, mechanical and electrical systems are good to go. The lifts are ready for the tens of thousands of people heading to the slopes. But what does it take to make all of that happen? Earlier this year I made a trip to Mount Snow, located in the mountains of Vermont, to see exactly what it takes to operate and maintain a ski resort.

Electromagnetic Compatibility of Variable Frequency Drives

Every electrical component can produce EMI when energized. Electromagnetic interference is caused by the voltage and current in the form of electric and magnetic fields. Depending on the strength of the fields, EMI can degrade or disrupt the performance of other devices. As power increases, the EMI can increase and if not considered in the design and installation of a device, significant problems can result. Some equipment intentionally produces emissions, such as cellular telephones and radio transmitters, while other equipment, such as computers, fluorescent lights, power lines and variable frequency drives produce unintentional emissions, so they’re referred to as incidental radiators.

Surf's Up - Broadband Over Power Lines

Are we on the edge of another technological tidal wave or will this just be a small ripple in the pond? Surfing the internet is once again beginning to move in a whole new direction. For the past several years there has been slow and steady growth towards using existing electric power lines for broadband. Known as “Broadband Over Power Line” or BPL, the concept is simple. In fact, electric utilities have been transmitting data on transmission lines to control substations for decades. Traditional pipelines for broadband have included cable and DSL but this new technology is often referred to as the “third pipeline.”

Dress for Success - PPE Selection

NFPA 70E has given a whole new meaning to the phrase “dress for success.” No, this is not about which shirt or tie to wear for a job interview. In this case, success means that if the very rare but potentially deadly arc-flash occurs, your chance of surviving with either no injury or only minor injury is greatly increased.

One slip of a screwdriver and an electric power system can act like a bomb releasing a tremendous amount of thermal energy, producing a blinding flash and pressure that sends molten metal and other debris hurling towards you at a frightening speed. In an instant, life could be changed forever.

U. K. Article - Fear of Flashover

PPE happens to be last resort in the UK risk control hierarchy behind removing and avoiding the hazard altogether. There is evidence that some UK companies adopt a comfort/protection balance argument such that it is better to allow a lower level of arc protection PPE rather than to insist on better protection that will be difficult to enforce because workers will not wear for comfort reasons.

How to Perform an Arc Flash Study in 12 Steps - Part 1 of 3

This is the first article in a three part series about how to perform an arc flash hazard calculation study that was published in the August 2007 Edition of NFPA's NECDigest Magazine. The series breaks the study process down into indiviual steps.

How to Perform an Arc Flash Study in 12 Steps - Part 2 of 3

This is the second article in a three part series about how to perform an arc flash hazard calculation study that was published in the October 2007 Edition of NFPA's NECDigest Magazine. The series breaks the study process down into indiviual steps.

Behind the Scenes - Ethanol Production

Recently, I had the opportunity to visit ICM, and learn how they have been working towards making the dream of energy independence a reality be engineering, building and supporting ethanol production facilities across North America.

How to Perform an Arc Flash Study in 12 Steps - Part 3 of 3

This is the third article in a three part series about how to perform an arc flash hazard calculation study that was published in the December 2007 Edition of NFPA's NECDigest Magazine. The series breaks the study process down into indiviual steps.

How Did We Get Here? The History of Electrical Safety

It seems like the more you attempt to learn about arc flash and electrical safety, the more confusing it becomes. A mixture of -letters such as OSHA, NFPA 70E, NEC, IEEE 1584, ASTM F1506 seem to be the secret language used by the electrical safety industry. Who created this alphabet soup of standards, and how did we get here?

Arc Flash - Unplugged

Dynamite, gasoline, gunpowder and electricity: What do these have in common? Each one can explode. Something as simple as the slip of a screwdriver can cause the electric power system to act like a bomb. Technically known as an arc flash, this potentially devastating explosion can occur when accidental contact is made between energized conductors or between one conductor and a grounded surface, such as an equipment enclosure.

U.K. Article Pt. 1 - Arc Flash - Not Just an Electrocution Hazard

A fundamental safety principle, which is embodied in U.K. legislation, is to design out, eliminate or remove the electrical hazard at its source. The Electricity at Work Regulations 1989 (EAWR 1989) 13 and 14 lead to the conclusion that the majority of tasks must be carried out with the equipment made dead or placed in an "electrically safe condition" as they say in the US. To work dead, the electricity supply must be removed in such a way that it cannot be reconnected or inadvertently become live again for the duration of the work. The Memorandum of Guidance HSR 25 on the Electricity at Work Regulations identifies the main features of an isolation system of work.

U.K. Article Pt. 2 - Arc Flash - Not Just an Electrocution Hazard

Working safely in accordance with the requirements of the Electricity at Work Regulations 1989 is about decision making. This includes the decision to work live in the first place through risk assessment. One of the factors that would need to be taken into account in deciding whether live proximity work could proceed is stated in the memorandum of guidance to the EAW Regulations "the level of risk involved in working live and the effectiveness of the precautions available set against economic need to perform that work". Even testing of electrical systems needs the same degree of care in decision making.

Arc Flash Warning Labels

Read the label? Use as directed? It sounds like I’m reading a prescription bottle. However, the warning label produced from an arc flash calculation study contains more than just the words Warning! Arc Flash and Shock Hazard It actually holds a lot of very specific information that can be used when preparing for work where electrical hazards may exist.

U.K. Article Pt. 3 - Arc Flash - Not Just an Electrocution Hazard

The need for risk assessment is embodied in European Law through directive 89/391 and is transposed into UK Law through Management of Health and Safety at Work Regulations. Most people are familiar with the general principles of prevention as laid down in these documents and in other UK regulations. They say that "Where an employer implements any preventative measures, he shall do so on the basis of the principles of prevention" shown below. The authors shown in italics on how these principles can be interpreted when it comes to arc flash prevention.

Arc Flash Boundary - Distance Equals Safety

When a bomb goes off, the further you are from the explosion, the safer you will be. This same concept applies to arc flash hazards. Whether you are a properly protected and qualified person performing the work or just an observer, the distance between you and the arc flash can make all the difference in the world.

Simplifying Arc Flash Studies - Select the Arc Rating First

Begin at the End - What Answer Would You like to Have? Simplifying arc flash calculation studies Would you like to know a little secret about how to simplify an arc flash calculation study? Perform the study backward. Well, not actually backward, it just seems that way

Performing the study: Arc rating > incident energy. An arc flash calculation study (AFCS) is one method that can be used to determine the level of flame-resistant clothing and personal protective equipment (PPE) that is appropriate for protection from the thermal energy of an arc flash.

Predicting Arc Flash Duration

Knowing how long an arc flash could last is the most important piece of information in predicting its severity. The duration is usually dependent on how fast an upstream protective device will trip. The longer it takes, the greater the incident energy and resulting hazard.

IEEE 1584 - 125 kVA Transformer / Less than 240 Volts Exception

One sentence in the IEEE 1584 Standard, IEEE Guide for Performing Arc-Flash Hazard Calculations, frequently has people scratching their heads: Equipment below 240V need not be considered unless it involves at least one 125 kVA or larger low-impedance transformer in its immediate power supply. What does this sentence mean? What is so significant about 240 volts and 125 kilovolt-amperes?

Get Ahead of It! - NESC Arc Flash Requirements

Determining how much incident energy could be available at a piece of equipment or location on a line is something you do not want to discover from a field test (accidental or intentional this means the only alternative is to predict it from calculations.

IEEE 1584 Two Second Rule

A lot can happen in two seconds. What may seem like the blink of an eye can feel like an eternity, especially during an arc flash. When calculating the incident energy as part of an arc flash study, sometimes the IEEE 1584 equations can produce unusually large values. Although many variables are included in these calculations, the two most significant are the magnitude of arcing short-circuit current and the duration of the arc flash.

Coordination and NEC 240.87

When selective coordination is critical, e.g., minimizing the extent of an outage, a common design practice is to use a main circuit breaker without an instantaneous tripping function and feeder breakers with one. Without an instantaneous, the main can time delay up to 30 cycles or 0.5 seconds.

Arc Blast and 40 calories/centimeter squared

You look at the arc flash warning label and scratch your head. Danger! No PPE Category Found. No personal protective equipment (PPE) category? Now what? This type of language is often on arc flash warning labels when the calculated incident energy exceeds 40 calories per centimeter squared (cal/cm²). What is so special about the number 40?

Using Correct Electric Utility Data

One of the first steps in performing an arc flash calculation study is to request short-circuit data from the electric utility company. This kind of request is pretty routine, and utilities have been providing this type of data for short-circuit studies for years. The problem is the data used for a short-circuit study may not be suitable for an arc flash study.

Keeping Skills Current in a Down Economy

What if you had been stranded on a deserted island for the past five years? By the time you were rescued, you would have missed the explosion of social media usage, including Facebook, YouTube and Twitter, as well as advancements in smart grids and wind and solar energy—it would be more than you could imagine. You may think, "How could the industry have changed so much? I was only lost for a few years."

What if you were stranded for just one year? You would have missed the latest tablet computer, the rapid development of smart phone apps and quick response (QR) codes (those odd looking bar codes for smart phone scanning). You even would have missed the latest edition of the National Electrical Code (NEC) and the 2012 edition of NFPA 70E.

Working Distance Mistakes

The term “working distance” appears 20 times in the 2012 Edition of NFPA 70E, the Standard for Electrical Safety in the Workplace. It appears 12 more times in the annexes. The working distance is an important component of the arc flash hazard analysis and is frequently listed on arc flash warning labels and in the arc flash report.

IEEE 1584—IEEE Guide for Performing Arc Flash Hazard Calculations 2002 defines the working distance as “the dimension between the possible arc point and the head and body of the worker positioned in place to perform the assigned task.”

Five common (and dangerous) working distance mistakes
Even though working distance seems to be a simple concept, it is not always properly considered when performing energized work. The following are five common mistakes: [Read More]

PREVIEW - Complete Guide to Arc Flash Calculation Studies

Jim Phillips, P.E. is author of the book: Complete Guide to Arc Flash Hazard Calculation Studies. There are many codes and standards exist that define arc flash protection and electrical safety requirements. However, no individual code or standard specifies how to perform the complete arc flash hazard calculation study.

This book is designed as a step by step approach to guide you through the entire study process. Using a series of flow charts, solved examples and calculation worksheets, the study process is broken down to a detailed step by step approach. From data collection to system modeling, calculations, analysis, labeling and recommendations and everything in between.