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Electrical Code for the Combination Inspector, Part 3

Posted By Randy Hunter, Sunday, January 02, 2011
Updated: Thursday, September 06, 2012

Last issue we made it through the "g” definitions in Article 100. In this article, we will finish reviewing selected definitions. Our first definition isin sight from(within sight from, within sight). These variations of phrase are used in various parts of the code, but would likely engender many arguments over meaning if theCodedid not include a clear definition. When we use one of these phrases, we are usually talking about the location of equipment in relation to the location of the disconnecting means. This definition specifies that the referenced equipment must be visible, and it must also be less than fifty feet away (see photo 1). Until recently, I thought this was a pretty simple concept and an easy-to-apply code requirement, but then I observed an installation involving a motor on a large conveyor system. The motor was located about 30 feet in the air on a platform, and the disconnect for the motor was located on a second platform (which also had another motor and associated disconnect). The two platforms were about 40 feet apart, but to get from the first platform to the second, you had to climb down the 30 feet, walk over about 40 feet then climb the stairs up 30 feet to the disconnect. Was the letter of the code met? Perhaps, but the intent of this requirement is that the disconnect is close at hand and easily accessible in case you need to operate it quickly and also that a worker can see the disconnect and maintain a level of safety when working on equipment. Now with OSHA requirements, we have taken this up a level with lockout tagout procedures.

Locations

Locationis separated into three distinct areas depending on the level of exposure to weather or moisture. First, we havedry location,which is a

Photo 1. Disconnects located in sight of the equipment they control

Photo 1. Disconnects located in sight of the equipment they control

location not normally subject to dampness or wetness. This location may temporarily be damp or wet, especially during construction. The next level isdamp location,which covers areas not subject to saturation with water or liquids, but subject to moderate degrees of moisture. This could include areas under eaves, or open covered porches, especially in areas of the country that have very high levels of humidity. The last definition iswet location, which covers those locations subject to saturation with water or other liquids and also those areas underground, in concrete or in masonry in direct contact with earth. Two examples of areas that fit into this category might be car washes and exposed exterior locations. Please keep in mind, not all of the wet location areas covered by this definition are exterior to a building, it is certainly possible to find areas inside buildings that are subject to all degrees of moisture or wetness (see photo 2).

Listed and Labeled

The next two terms to cover work together, and actually need to be reversed to help make sense. First we will coverlisted, which means that the equipment, materials, or services are evaluated by an organization acceptable to the authority having jurisdiction (AHJ). This service is generally done by a nationally recognized testing laboratory (NRTL). Most commonly this is done by organizations recognized by OSHA as a NRTL. However, you will notice that the actual code language states "acceptable to the authority having jurisdiction,” so it is really up to the AHJ to determine which organizations are accepted. The second term islabeled,which is usually the after-effect of listing. Once an item is listed, a label is affixed to the equipment stating it has been inspected and listed to a standard for that type of equipment. The listing and labeling requirements are often overlooked in many areas or jurisdictions. This is due to the fact that many of us are not familiar with the requirements for listing and labeling. This would include unique, custom-fabricated, or modified equipment. My personal recommendation is to establish a contact with a knowledgeable resource who works with a listing agency (or agencies) who will be willing to answer questions you may have if you see something that just doesn’t look right.

Overcurrent and Overload

We’ll jump toovercurrentandoverload. While these appear to go together, they are unique concepts and I will explain why. An overcurrent is any current in excess of the rating of any equipment or conductor. On the other hand, an overload is the operation of equipment or conductor in excess of its full load rating, which if it is not stopped, will eventually cause damage or dangerous overheating. A short circuit or fault to ground are not overloads, however, they are overcurrents. Overloads usually have a longer duration and result in a thermal reaction of an overload device in order to shut off the circuit.

Raceway

Photo 2. This receptacle may be in a wet location, while the light fixture is located in a damp location.

Photo 2. This receptacle may be in a wet location, while the light fixture is located in a damp location.

Our next definition israceway, which is simply an enclosed channel designed specifically for holding wires, cables or busbars. Sometimes there is confusion with this concept since we have several types of raceways that look very similar to manufactured cable assemblies. Cable assemblies are generally manufactured and listed to a UL Product Standard that contains very specific requirements for the design of the cable, and come as a complete system with the conductors inside. Alternatively, a raceway will have conductors installed in the field. The fill factors and installation requirements for cable assemblies and raceways that look similar may be quite different.

Separately Derived System

Separately derived systemis premise wiring that comes from a source other than the service provided to the premises by the utility, and it does not have a direct connection to the service. In the past, this system was usually generators or transformers, but now we have many alternative energy systems which can qualify as a separately derived system. These systems may trigger many specific code requirements, which will be covered as we get into the body of the code.

Service

Photo 3. These light bulbs would be considered utilization equipment.

Photo 3. These light bulbs would be considered utilization equipment.

The next four terms are all related: they areservice,service drop,service equipmentandservice lateral. Let’s start with service drop and service lateral; these are the wiring methods used from the street main or transformer to the premises service equipment. The difference between a drop and a lateral is the service drop is run overhead, whereas laterals are underground. Both types are covered under the general termservice conductors;it is just their location that gives them different names. Most new construction, if it is in or around metropolitan developments, is now required to run as much as possible underground, so the term service lateral has become the norm for a high percentage of construction. Also, the service drop conductors and laterals may be owned by the utility; if so, they are outside the scope of theNEC. Let’s move on to service equipment, which is usually one or more circuit breakers or fused switches located near the point of entrance of the supply conductors. It is usually located at a point close to the meter. Now to put this all together, the combination of the items in this paragraph constitute theservice; sometimes it’s just easier to start at the bottom of a list and work your way up, as is the case with the service definitions.

Short-Circuit Current Rating

Short-circuit current rating(SCCR) is a term that was largely overlooked for many years. The installer would size the wire, size the overcurrent protection device for the wire size, the load and voltage, and then head down the road. However, in the last decade, we’ve become enlightened and realize that we need to address the SCCR as well. The SCCR is the rating that equipment must have to withstand the maximum current which could possibly flow to that device. The reason we’ve heightened our awareness of this is to prevent catastrophic failures which result in the loss of property and possibly life. With the increased legal activity and OSHA enforcement which may occur after any large failure, we now pay a lot more attention in enforcement to make sure the installation can handle the available fault current. This involves several steps and calculations depending on the equipment, the fuses or breakers involved and the wire. The first step before any of these items can be calculated is the determination of the fault current available at the service point. You must find out what that value is from the serving utility. If the inspector does due diligence in verifying the values and calculations during plans check and field inspections, all equipment that is installed will be sized for the fault current available. In the event of a fault of any kind the equipment will operate as intended and avoid catastrophic failures. This is a newer concept that I’ve had to add to most classes just in the last few years, but it is a very important concept to introduce early in the course of study and is essential to safety.

Switches

Photo 4. Weatherproof

Photo 4. Weatherproof

Sometimes we have a simple term such asswitch, which we all know is just a little device in the wall that turns on a light or some device. However, at this point I will encourage you to once again get your code book out and notice that a switch might not be just a switch in every application. Once you review all the different types of switches, you will see that it is a good example of the many items in every trade that we may think of in a certain way (an apple is an apple). However, the more we learn the more we find out that we need to take the time to learn the nuances of even simple terms and to understand when there may be a variety of meanings (is that a Granny Smith or a crab apple?).

Thermally Protected

Thermally protectedis the next term I usually cover to those new to the electrical code. It’s applied to motors, and it means that the motor has a device in it which senses the current the motor draws. If for some reason the motor starts to pull too much power, the thermal protector will open the circuit to protect the motor. The best example to illustrate this is the push button on the bottom of your garbage disposal. I usually ask my class if they have ever jammed their disposal and had to reset the button on the disposal. This example usually rings a bell.

Utilization Equipment

The next term we’ll cover is one of my most memorable. The reason it is memorable was the circumstance where I came across it. I remember during a Master’s test I got to a simple question which stated, "Something that utilizes electricity?” It almost stumped me, as I had just answered over 100 questions of every type throughout the code book and suddenly I went blank — was it in Article 430, or was it 440, maybe 424? After what seemed like a long time, I finally decided to look in Article 100, and there it was, word for word in the definition forutilization equipment. Ever since that question, I make sure people understand that something that uses or consumes electricity is utilization equipment (see photo 3).

Voltage

Voltageis the next term to cover, and it has three unique definitions under the headingsvoltage(of a circuit),voltage, nominalandvoltage to ground. Each represents a slightly different application. To start with, let’s take nominal voltage, which is the voltage reference used for equipment and code language to identify the voltage system we are working with. For instance, frequently we say 110 volts when in fact you won’t find this in the code, since the nominal voltage in the code is 120 volts. In Article 430, you will find unique nominal voltages for motors. Voltage of a circuit is identified as the maximum voltage between any two conductors of a circuit; so for a 120/208 system the circuit voltage would be considered 208 volts, which is the maximum possible between two conductors. The last voltage term is voltage to ground, which is the maximum voltage between any one conductor and ground. This voltage will vary on systems depending on how we’ve grounded the service. We will cover more on this later when we discuss services. Voltage to ground is commonly used when we are working on the height clearances for conductors over streets, yards or buildings.

Watertight and Weatherproof

The last two terms for us to cover in the definitions also go together, they arewatertightandweatherproof, which are similar but have two levels of construction. The first is watertight which very simply means that moisture will not enter the enclosure under a specific test standard. Weatherproof has a little different concept which actually allows moisture to enter an enclosure, as long as it doesn’t interfere with the successful operation of the enclosed equipment. With this in mind, most equipment that is weatherproof is designed with a topside and has small weep holes in the bottom to allow any moisture which might accumulate within that enclosure to drain out (see photo 4).

This concludes the major definitions which I have always used as the basis for teaching theNEC. We will from time to time refer to other items in Article 100; however, the ones pointed out in this and the previous article will give us a good start. Once again, I would encourage you to review the other items in Article 100, as it can only help with the process of learning the electrical code. In the next edition, we will actually get into the meat of the code with Article 110, which often doesn’t get the attention it deserves since wire sizing and overcurrent or raceway installation issues often get most of the coverage. However, Article 110 covers a variety of the simple rules which are often overlooked and lead to code violations, which can come as a rude surprise to an installer. Hope you are hanging in there and are ready for the next issue.


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Tags:  Featured  January-February 2011 

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An Introduction to Electrical Fundamentals

Posted By Stephen J. Vidal , Sunday, January 02, 2011
Updated: Thursday, September 06, 2012
Benjamin Franklin

By strict definition a material can be classified as either a conductor, an insulator, or a semiconductor based on its electrical properties. Before getting into the definition of each of these, a brief introduction to atomic theory is in order.

The atom is the smallest individual structure that makes up any chemical element while retaining properties of the element. The atom has a nucleus that contains protons and neutrons. Electrons orbit the nucleus at various distances and with varying amounts of energy. Protons are positively charged particles, electrons are negatively charged particles, and neutrons are uncharged particles. These electrons known asvalence electronsare what we are primarily interested in from an electrical perspective. The valence shell is the outermost orbiting shell around the nucleus of the atom. It is important to note that electrons in the valence shell have higher energy than those orbiting closest to the nucleus. The distance away from the nucleus also allows these valence electrons to escape easier. The electrons that are given up from the valence shell become known asfree electronsand contribute to current flow. Figure 1 shows the atomic structure of Hydrogen.

Conductor

Figure 1. Atomic Structure of Hydrogen

Figure 1. Atomic Structure of Hydrogen

A conductor has the property of conducting electrical current very easily. Examples of conductors are gold, silver, copper, and aluminum. Gold and silver are not used as conductors in electrical construction because they are extremely cost prohibitive. Copper and aluminum are the traditional conductors used in electrical construction. These chemical elements are characterized by atoms that contain electrons in the valence shell that are not tightly bound and can easily contribute to current flow. Most conductors are metals and have high conductivities based on their resistivities.

Insulator

An insulator has the property of not conducting electrical current very easily. Examples of insulators are glass, porcelain, rubber, and mica. Note how these products are not individual chemical elements but rather chemical compounds made up of different chemical elements. These chemical compounds are characterized by atoms that contain electrons in the valence shell that are tightly bound and do not easily contribute to current flow. Most insulators are non-metals and have low conductivities based on their resistivities.

Semiconductor

A semiconductor has the property of behaving like something in-between an insulator and conductor. Examples of semiconductors are silicon and germanium. Silicon and germanium in elemental form are poor insulators and poor conductors. But when combined with other chemical compounds these devices can become insulators, conductors, or variations of both. Through a process known as doping, impurities are added to elemental silicon or germanium allowing the electrical properties of these materials to be changed.

So we have now learned that conductors can conduct current very easily, and insulators cannot conduct current very easily. What exactly is current and how does it flow through a conductor? To understand how current flows through a conductor we have to discuss four important terms: voltage, current, resistance, and resistivity.

Voltage

Figure 2. Example of Ohm's Law

Figure 2. Example of Ohm's Law

The technical definition of voltage is the unit of potential difference between two points when 1 joule (unit of energy) of work is expended to move a test charge of 1 coulomb (unit of electric charge) from point A to point B. The unit of voltage is the volt and the meter used to measure voltage is the voltmeter. The voltmeter is placed in parallel with the device under test. Depending on whether the voltage representation is an AC or DC waveform, terms you will encounter areAverage,RMS(root mean square), andP-P(peak to peak).

The technical definition of current is the movement of a test charge of 1 coulomb past a given point in 1 second. The unit of current is the ampere and the meter used to measure current is the ammeter. The ammeter is placed in series with the device under test.

The definition of resistance is the opposition to current flow that is measured when electric current flows through a conductor. The unit of resistance is the ohm and the meter used to measure resistance is the ohmmeter. A very useful equation known as Ohm’s Law is helpful in solving for the derived unit of resistance. See figure 2 for an example of Ohm’s Law.

Sometimes a mechanical analogy helps to keep these terms in perspective. Consider a garden hose that supplies the flow of water to a water fountain. The voltage would be the pressure of the water in the hose, the current would be the flow of water through the hose, and the resistance would be the friction the hose presents to the flow of water. The water fountain would be the load because it is performing some useful work.

Resistivity

Figure 3. Ohm's Law

Figure 3. Ohm's Law

The last term to define is resistivity. Resistivity is the resistance offered by a material to the flow of current designated by a specific length and specific cross-sectional area. The unit of resistivity is the circular mil-ohm/ft. One circular mil is the area of a circle having a diameter of 1 mil. One mil is 1/1000thof an inch. Copper is a conductor and therefore has a low resistivity and high conductivity. Rubber is an insulator and therefore has a high resistivity and low conductivity.

An example will help to clarify these points. Let’s take a #16 THHN copper conductor with a length of 100 ft. First recognize that the copper wire is a conductor and has a very low resistivity which means it will pass current very easily. Next recognize the THHN (thermoplastic insulation, high heat resistant, dry location only, nylon jacket) insulation is an insulator and has a very high resistivity which means it will not pass current very easily. From Table 8 Conductor Properties in Chapter 9 of theNEC,we find the diameter of #16 THHN to be 0.051 in. The resistivity of copper is 10.371 cmil-ohm/ft. Let’s calculate the resistance of 100 ft of this conductor.

L = 100 ft
Ρcu = 10.371 cmil − Ω ⁄ ft
D = 0.051 in = 51 mils
A = 2601 cmil
R (100 ft) = (ρ* (L)/A
= (10.371) * (100) / 2601

= 0.398 Ω

Voltage, current, resistance, and resistivity are important electrical units. Conductors and insulators are very common materials used every day in electrical construction. These core definitions will allow for further discussion of devices like resistors, capacitors, and inductors and how they perform in a variety of circuits and under a variety of conditions.


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Tags:  Featured  January-February 2011 

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Chuck Mello: 2011 International President

Posted By Chuck Mello, Saturday, January 01, 2011
Updated: Wednesday, September 05, 2012
Chuck Mello

As we begin this next year, it is a good time to reflect on the association in general, and most of this article will be some of my reflections and future goals, long range and for 2011 specifically. As I look back on my twenty-seven years as an IAEI member (as both an associate and inspector member), and the last eleven years on the International Board, this has been an unbelievable experience. I am deeply honored and humbled by your support and trust that have been placed in me. My most important goal is to serve and to represent you in the best way that I can.

I started my education in the electrical industry, as many of you probably did, in grade school science classes. I remember for my 6th grade science fair entry I built a mock stud wall assembly of 2x4s and plywood and wired together a pair of 3-way switches and three 4-way switches to operate a 120-volt light bulb. While my father did not share the level of enthusiasm as I had, he left me to my tinkering, I am sure with the hope that I did not somehow burn the house down. For that project, I had to explain how the wiring was done and how the circuit operated to turn the light on or off from any of the five positions. Moving from that humble beginning, I completed a college degree in electrical engineering with a power specialty at Oregon State University. Over the next thirty-eight years I have been able to work and continue to learn about electrical equipment and safe installations. My hands-on education was supplemented with needing to understand theNEC, as well as product standards such as IEEE and UL. All along the way, I also found myself being a teacher to electricians, inspectors and other engineers on various job sites and also doing seminars on these topics. As my career progressed, I moved into dealing more with product standards and into field evaluations of electrical products that were not certified as well as teaching electrical safe work practices. Over this time, I obtained licenses as a master electrician and electrical contractor from Louisiana, New Orleans, New Mexico, Nevada and Colorado.

Photos 1 and 2. New International President Chuck Mello receives the gavel from outgoing International President Rick Maddox.

Photos 1 and 2. New International President Chuck Mello receives the gavel from outgoing International President Rick Maddox.

I became a member of IAEI when an inspector asked me to make a presentation on installation and testing of ground-fault protection to the Oregon Chapter. I had met this inspector on a job site where I was performing the required GFPE field testing and was explaining to him how this particular ground-fault system worked in normal operation and when a ground fault occurred. He thought maybe the local IAEI chapter would be interested in this as a more formal presentation. Shortly thereafter, I became an associate member in the Oregon Chapter and was mentored by this sponsor and encouraged to attend meetings on a regular basis. I became active on the chapter board and several years later, after changing status to an inspector member, ultimately became the chapter president. I was the education chairman for the NW Section for several years and then started my tenure on the International Board. All through this time, I have been active with IAEI, both as a student constantly learning from all the members I have had the privilege to interact with, as well as being an instructor, and sharing what I have learned. Even as the instructor, I learn something from each class. I owe to a large degree whatever successes I have had in my career to my IAEI membership and the many opportunities it has given me to learn and to network with very special people all over North America. I continue to see new learning opportunities with PV, wind generators, electric vehicles, and now the "Smart Grid” with all its new changes both in the NEC as well in products.

Photos 1 and 2. New International President Chuck Mello receives the gavel from outgoing International President Rick Maddox.

Photos 1 and 2. New International President Chuck Mello receives the gavel from outgoing International President Rick Maddox.

When your International Board of Directors conducted the search for the new CEO/Executive Director, they heard the message from the membership that IAEI needed to evaluate our traditional way of doing things and look to some new directions. Our core purpose and mission remain the same, but we need to have some new beginnings while not necessarily losing our key core traditions. We need to explore how we are reaching out to our present members, but just as important, how we can reach out to and encourage participation by our new members. One of these avenues is through online communications and social network links. While the traditional division/chapter/section meeting with educational programs is still of great value and we need to continue to promote that, it is a fact that many younger people seek their education and networking by other means. If we are to stay relevant, we need to participate in both the traditional meeting and these electronic mediums and maximize the benefits of each. Otherwise we will just become irrelevant, deferring to others that do communicate that way. The hiring of Mr. Dave Clements is part of our new beginnings. In addition, the International Membership Committee has formed an ad hoc committee specifically to develop a strategic plan for membership and how we can better the membership for IAEI. A number of years ago, we set a goal of "30,000 members in 2000,” but what we failed to do was to develop and put a firm plan in place to accomplish that goal. This new ad hoc committee will be the ones to make that plan. The board has also tasked the Long Range Planning Committee to develop an overall strategic plan, a five-year plan of what IAEI should look like and be doing in five years and on out. This means looking at others in the electrical and inspection industries and forming strategic partnerships and then building on the synergies that can result from those partnerships. This includes our traditional activities with NFPA, NECA, and NJATC and others, but will also move to include more activities with ICC, IAPMO (International Association of Plumbing and Mechanical Officials), IEC, and the home inspectors associations (NAHI, ASHI, AAHI, and InterNACHI, to name a few). It also means planning for IAEI staff and facilities to accomplish this and how we will be funding that now and in the future. Lastly, it means looking at our resources and funding models to ensure we have the necessary resources there when needed.

2010 was a year of significant changes with the selection, hiring and transitioning of our new CEO/Executive Director. I see 2011 as a year with five main areas to move IAEI forward:

1. Membership growth and retention through the efforts of the Ad Hoc Membership Committee and very importantly continuing efforts at the local level;

2. Formalizing the Strategic Plan for IAEI overall and setting the course to meet those strategic goals with action plans and resources;

3. Finalizing the decisions for our building and moving that forward so that we provide adequate facilities with an eye to reduced cost of operations, and maintenance;

4. A complete review of our International Bylaws, International Operating Rules and Model Bylaws to ensure we are operating as we say we should be and to make changes where needed so we are set for our future direction and growth; and

5. Formalizing to a greater degree IAEI positions on NEC adoption, inspector qualification/certification, and support of the safety system we have in place that meets our mission.

As I am writing this, I am very excited about what lays ahead. I see an international board of directors that shares my enthusiasm for moving IAEI forward. My enthusiasm is tempered by the reality of today’s economy, and we will have to adapt to that reality as needed, but we cannot let this situation prevent any action to move forward. What I do know is we have a dedicated CEO in place, a dedicated staff and a membership that believes in what we are trying to accomplish. I look forward to a very productive year.


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Tags:  Featured  January-February 2011 

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The Art of Dispenser Safety: A Safe Environment for Vehicle Fueling Station Maintenance

Posted By Jonathan Cadd , Saturday, January 01, 2011
Updated: Wednesday, September 05, 2012
Photo 1

With the new 2011 National Electric Code hitting the streets all over the country, I am often asked, "Are we there yet?” No, this isn’t that yearly trip to the in-laws’ house halfway across the country, with one question seared into your brain that you know you will hear 500 more times before you arrive.

It’s the other burning question, Have we finally constructed the descriptive language that will convey the importance of avoiding and, perhaps, finally prevent an unsafe environment when it comes to an emergency in regard to vehicle fuel dispensers or to the servicing and maintenance of vehicle fuel dispensers?

Did we cover, at least for now, the latest technologies and integrate them into the requirements of the NEC properly; and did we make provisions to embrace new technologies? I have asked the question and had this same discussion with many of my colleagues. With many facets of the vehicle fueling industry—from manufacturer, installer, and inspector alike—all can agree that the language is much better than before, and our continued discussions are still passionate and filled with many talking points and scenarios that help us understand the intricacies that are involved with the subject.

We all have a slightly different take on simultaneous disconnect of all conductors andhowit should be done. Whether we will see a day when simultaneous disconnect can all be handled by a single device or combination of devices the use of which becomes as routine during an installation of a vehicle fueling dispenser as a GFCI is in a dwelling unit still remains to be seen.

Photo 2. Emergency shut off button

Photo 2. Emergency shut off button

We are completely in agreement, however, that simultaneous disconnectshouldbe done; and we are still perfecting the verbiage as we follow the industry, and keep our fingers on the pulse and blend technology with safe installation practices and requirements. In the end where will our efforts lead us, will we accomplish the task once and for all and achieve the safe environment we seek to provide? In this latest look at a well-discussed subject, we will visit previous technologies and methods, take a look at current methodologies, and see what the new 2011NECprovisions have in store for the industry in the quest for a safe environment for the servicing and maintenance of vehicle fueling dispensers.

With the many technical advances that have been made to ensure the safe everyday use of modern fuel dispensers in the motor vehicle fueling industry, there still remains the question, "How do we ensure that the requirements in theNational Electrical Codeare being adhered to,” particularly the provisions in NEC 514.11 and 514.13, when there is an emergency, or it’s time for service or maintenance of the fuel dispensers?

For many years and still today the practice of field-installed combinations of wiring and equipment that kind of gets the job done is, and has been, normal practice when it comes to simultaneously disconnecting "allconductors of the circuits, including the grounded conductor.” Many of these jobsite solutions are not listed as an assembly, nor have the individual components themselves been listed, labeled, or identified for the application.

The days of the old full-service gasoline station of our parents and grandparents have gone the way of the dinosaur; and in its wake, we have the modern self-serve vehicle fueling stations that offer fuel 24 hours a day, 7 days a week, 365 days of the year.

Photo 3. Unlike earlier dispensers, these versions are mostly solenoids, piping, and computer hardware

Photo 3. Unlike earlier dispensers, these versions are mostly solenoids, piping, and computer hardware

These modern service station dispensers of the vehicle fueling world are ready and willing to dispense fuel at a moment’s notice, and while, yes, some things have changed a bit, now you pump your own gas; checking the oil and getting your windows washed are out, but if you have the time there is gas a plenty to be dispensed. Nowadays, however, no one is in attendance at many of these modern vehicle fueling establishments when they are a fuel-only site without a convenience store; and if there were to be an adverse situation that occurred, the e-stops wouldn’t do any good if they are not properly installed and identified, and there is no one there to use them, or they may be installed, wired or modified in an unlisted or tested manner, and fail to perform as expected in an emergency. Conversely, if a person were to be performing service or maintenance on the fuel dispensers, what guarantee is there that the environment is safe for the operation? Who guarantees that all the field-built or modified wiring and equipment will function properly as intended without that third party certification?

With the advent of the very latest technologies like pump top advertising via premises-powered LCD screens affixed to the tops of the fuel dispensers, we now have more ignition sources for what might very well be an accident waiting to happen. With the rigorous pace that these new self-service dispensers are required to keep in this economy where every penny counts, it doesn’t leave a lot of time for downtime for service or maintenance.

This extended maintenance schedule and the sheer demands on the equipment can cause pumps, seals, and gaskets to fail prematurely, creating a dangerous situation that might affect not only the individual who is servicing or maintaining the dispenser, but also the everyday user.

So what do we do? Many vehicle fueling stations run just fine, utilizing methods that have been field-wired to achieve a simultaneous disconnect of the conductors that were thought to be current-carrying or at least carrying enough current to cause a concern. Some critics will even hold that as long as the line voltage is disconnected the low-voltage circuits are of little or no concern. Is this true?

Photo 4. Here we see the humble beginnings of a super station

Photo 4. Here we see the humble beginnings of a super station

If there is no listed and labeled device or a known piece of utilization equipment that can fulfill the requirements for maintenance disconnects for fuel dispensers, what is the solution? Let’s look at what has been done to satisfy this requirement. All manner of shunt trip devices, contactors, and the like were used in many vehicle fueling stations and are still used today.

The issue here is that there is no guarantee that these field-wired, unlisted and untested methods would hold up to the environment to which they were subjected or that they could actually perform to an established product standard. Certainly, one would not want to install such an arrangement of wiring and devices knowing that there is, or even could be, the potential for serious damage or loss of life.

Without applying even the basic premises of theNECand certainly starting at 110.3(A) and following through with 110.3(B) at the very minimum, there is no way for anyone to be sure of the performance of these methods. Many installers and inspectors alike have throughout the years applied their own brand of interpretation to the subject and a lot of the time best practices and methods prevailed where there was lack of consensus on the requirements; many of those installations exist today.

Photo 5. Technology has led the user to believe that vehicle fueling facilities are safe and foolproof. Slide the card, pump the gas. But safety still needs to prevail at maintenance time.

Photo 5. Technology has led the user to believe that vehicle fueling facilities are safe and foolproof. Slide the card, pump the gas. But safety still needs to prevail at maintenance time.

Notwithstanding that proper plans were drawn up and submitted, ultimately reviewed, and are now on a jobsite ready for implementation, the question is still there. Now with new verbiage in the 2011NEC, can we finally say with certainty that we have enough language in the requirement to ensure that level of safety? Can we ensure with this new language that when the green tags are all affixed, we are starting out with a better installation that will ensure a safer environment? I think so. We now have very strong, yet simple, language — "All associated power, communications, data, and video circuits”— added to the mix and it certainly quantifies which circuits and conductors are to be simultaneously disconnected.

This language should be clear to the reader and should assist the installer and inspector alike in providing that safe environment for vehicle fueling establishments. There is no more discussion about types or amounts of voltage, about what will make a spark and what won’t — everything gets disconnected now.

We have thwarted the fire triangle again by removing the ignition source, where a fuel source might exist. We all understand that the third part (oxygen) is in abundant supply all around us and that there is little to be done with this element short of making sure
that the other two elements are controlled or removed from the equation.

Let’s look at the service and maintenance side covered inNEC514.13. Once again we have strong and effective, yet simple, language. "Each dispenser deviceshallbe provided with a means to removeall external voltage sources, including power, communications, data, and video circuits, and including feedback, during maintenance and servicing of the equipment.” This is the language that was discussed and started in past code cycles by the many authorities from the fuel industry, reviewed and amended by today’s authorities and code panel members and forged into finite, yet all encompassing, language that will take into account the new technologies that are no doubt on their way.

I think that it is clear to the reader that the question has been answered and that even the elements of ignition themselves have been spelled out, leaving very little ambiguity or discussion at this point. Until new sciences and technologies emerge, we have gained a solid foothold on just how to ensure the safe environment that the industry demands for installer, inspector, and consumer.

Photo 6. Signs warn users not to mix fuel with any source of electricity. Static discharge in dryer climates has become problematic.

Photo 6. Signs warn users not to mix fuel with any source of electricity. Static discharge in dryer climates has become problematic.

There is always a since of urgency when it comes to electrical safety, and particularly when we deal with hazardous (classified) locations. Keeping up with industry is a daunting task in and of itself, much less making sure that there is adequate language to enforce the requirements necessary to ensure safe environments. The electrical industry as a whole works diligently — year after year, code cycle after code cycle — to actively provide for a safe working environment not only for themselves but for all who will come into contact with electricity.

In this article, we have examined the immediate hazards of the dispenser in the vehicle fueling environment and the ultimate goal of the industry. We have seen what has transpired in the past due to the lack of hard-hitting language, the lack of critical code requirements and the lack of communication throughout the industry added to the extreme pace of the technological advancements in the dispenser industry.

We have also seen the strong response and formidable answer handed down from the fueling and electrical industry professionals by way of the code-making panel and theNECgoing the distance and taking another hard concentrated look at how to clarify, to maximize and to convey the language required to assist the installer and inspector alike, and providing that language to ensure the safe environments that we have come to expect, where time is precious and maximization of that time is the ultimate goal.

And so with new information at your fingertips, with all the reading and discussion you will have between the former and the new requirements for vehicle fuel dispensers in 514.11 and 514.13, you will, like many industry professionals, reach a conclusion; but you still have to ask the question, don’t you? "Are we there yet?”


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Ring in Some Financial New Year’s Resolutions

Posted By Jesse Abercrombie , Saturday, January 01, 2011
Updated: Wednesday, September 05, 2012

Now that 2011 is here, you may want to make some New Year’s resolutions. Planning to volunteer? Go to the gym more often? Learn a new language? All worthy ambitions, of course, but this year, why not add some financial resolutions as well?

Which resolutions should you make? Here are a few ideas to consider:

Boost your retirement accounts.No matter how old you’ll be in 2011, one thing is certain — you’re a year closer to retirement than you were in 2010. And that’s why you’ll want to increase your contributions to your retirement accounts. If your salary is going up in 2011, boost the amount you defer for your 401(k) or other employer-sponsored retirement plan, such as a 403(b) plan (if you work for a school or other tax-exempt organization) or a 457(b) plan (if you work for a state or local government). With tax-deductible contributions, tax-deferred growth of earnings and several investment options, these types of plans are tremendous ways to save for retirement. And try to "max out” your traditional or Roth IRA, too.

Look for opportunities.With the uncertainties in the economy and the volatility of the financial markets, many people decide to head to the investment sidelines for a while. Yet, this environment may actually be a good one for investors with patience, discipline and the ability to look beyond yesterday’s headlines. For one thing, many quality securities are now good values. Also, we’re still seeing low inflation and low interest rates — factors that may lead to greater economic demand and improved strength in the financial markets.

Don’t over-react to market swings.Over the past few years, we’ve seen plenty of sudden, sharp swings in the financial markets, and you’re likely going to see more of them in 2011. Don’t over-react to either the ups or the downs of the market. Over-reacting leads to short-term thinking — and successful investors are the ones who can maintain a long-term perspective.

Rebalance when necessary.At least once a year, review and rebalance your portfolio, as necessary, to make sure it still reflects your goals, risk tolerance and family situation, all of which can change over time.

Reduce your debts.While the sluggish economy of the past couple of years has obviously been a cause of concern for everyone, we have seen one silver lining in that many people, concerned about overspending, have shed some of their debt load. The less money you have to spend on your debts, the more you’ll have available to invest for your future, so do what you can to cut down on what you owe.

Maintain adequate cash levels.As an investor, you’ve got at least two good reasons for maintaining enough cash in your portfolio. First, having adequate cash available means you’ll be ready to act quickly to take advantage of good investment opportunities. And second, by having a cash cushion, you won’t be forced to liquidate long-term investments to pay for short-term needs such as a major car repair, a new furnace, a big doctor’s bill, and so on.

By following these suggestions, you can position yourself to make progress toward your long-term goals in 2011 — and in all the New Years that follow.


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Energy Update: Technology Converts Waste Material into Electricity

Posted By USDA , Saturday, January 01, 2011
Updated: Wednesday, September 05, 2012

A dairy farm in North Troy, Vermont, is using an innovative technology to convert farm waste products, such as manure, into electricity. The project was funded with assistance from USDA.

"Anaerobic digesters like the one at Chaput Family Farms will benefit our environment as well as America’s dairy farmers, who can profit from the production and sale of this renewable energy source,” said Natural Resources Conservation Service (NRCS) State Conservationist Vicky Drew. "In addition to reducing greenhouse gas emissions through the collection of methane, the digester will also reduce energy needed to produce and haul bedding to the farm by recycling the manure onsite into a dry bedding material for the cows, creating a closed-loop system.”

USDA Rural Development Vermont State Director Molly Lambert added, "Expanding the nation’s renewable energy sources is a priority of the Obama Administration and Agriculture Secretary Tom Vilsack and is consistent with a memorandum of understanding the United States signed in Copenhagen last December to work together with dairy producers to reduce greenhouse emissions by 25 percent by 2020.” She was joined on the tour of Chaput Family Farms by Rural Business-Cooperative Service Administrator Judith Canales and Farm Service Agency State Executive Director Robert Paquin.

The 300 kilowatt anaerobic digester system that the USDA officials toured at Chaput Family Farms will digest manure from a dairy herd, produce biogas and combust the gas to generate renewable energy on a continuous basis, and provide digester effluent for use as crop fertilizer and for cow bedding material. USDA Rural Development helped finance the digester with a loan and grant through the Rural Energy for America Program (REAP), authorized through the 2008 Farm Bill.

"This project highlights the way USDA agencies are working together to help rural farmers and businesses,” Canales said. "Supporting our farmers in projects like this is good for them, good for the environment, and good for businesses and residents throughout the community.”

Chaput’s digester is the first to go online through Vermont’s Standard Offer Program. The state will pay the farm a fixed price of 16 cents per kilowatt hour for the next twenty years. In addition, the farm will receive a renewable energy credit of 4 cents per kWh for the next five years through Central Vermont Power Service’s "Cow Power Program.”

The farm will produce all of its on-farm electricity, heat, hot water and bedding for the cows. It will sell the excess power to the local utility. The excess bedding will be sold to local farms.

USDA is extensively involved in renewable energy development efforts. The REAPprogram provides development assistance, grants for energy audits and funds to help agricultural producers and rural small businesses purchase and install renewable energy systems and make energy efficiency improvements. NRCS provides technical and financial assistance to producers for anaerobic digesters through the Environmental Quality Incentives Program (EQIP), and this year funded four new digesters in Vermont. NRCS offers technical and financial assistance for practices that are necessary components of anaerobic digesters; such as waste storage facilities, waste transfer, composting facilities, solid/liquid waste separation, nutrient management, and many others. NRCS developed the Agricultural Energy Management Plan (AgEMP) Conservation Activity Plan that can assist producers with on-farm energy conservation.

USDA’s Farm Service Agency (FSA) recently implemented a new conservation loan program that can be used to finance anaerobic digester projects that have been approved by NRCS. FSA will make direct conservation loans of up to $300,000, and will guarantee loans made by commercial lenders up to $1.12 million. FSA conservation loans can be made in conjunction with grants and other commercial financing. More information about USDA renewable energy programs is available from any State USDA office or by going to: http://energymatrix.usda.gov/.

Chaput Family Farms is a partnership of brothers Reg and Mike Chaput. Their legal partnership began in 1991 and was the result of the consolidation of four farms owned individually by Reg, Mike and their father Leo. The 1,800-acre farm milks about 830 cows. The digester was constructed to accommodate future expansion and is designed to handle manure from 1,600 mature cows plus young stock. The farm has also participated in EQIP to improve water quality concerns around the barnyard.


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Inspection Best Practices and More Inspection Perspectives

Posted By Thomas A. Domitrovich, Saturday, January 01, 2011
Updated: Wednesday, September 05, 2012

As members of IAEI, we are among some of the best when it comes to inspectors, something of which we must take advantage when it comes to doing what you do on a daily basis, inspect. We work hard across the country to understand the National Electrical Code and all of its grey areas as well as the application of products in our industry, but sometimes it is that one overlooked detail, like how do you conduct an inspection, that can make all of this knowledge for naught. If your methods of executing the inspection are sloppy and erratic, there is a good chance that a code violation goes overlooked or completely missed because a room was skipped. New inspectors especially have a daunting task in front of them. Not only must they become masters of the NEC, they must deal confidently with those who will question their objections and with the stress of time management; and they must also learn the fundamentals of how to conduct the inspection itself. The question of how to conduct an inspection may seem trivial to a person who has been inspecting for more than twenty years but be not mistaken—remember back when you first began—this is not as easy as it seems.

Figure 1

Figure 1. With 113 respondents, and more coming even after the survey was shut down, this survey was well received and very popular. All of the 102 inspector respondents to this survey were IAEI members. The message I received loud and clear was how eagar IAEI members are to help others succeed.


Simply Moxie

I never cease to be amazed by some electrical inspectors when they spout article, section and titles of the NEC as if they have the entire book memorized, including the year that particular section was adopted in the code. How in the world can a person absorb that much information and just how long does it take to achieve that level of expertise? are thoughts that echo in my head. I am amazed when walking a site with a seasoned electrical inspector, watching as his/her eyes scan an installation, and a violation is seen. Without blinking an eye, he gives an article and a section number and shows me exactly what was not installed correctly. Not only do I have the article and section but if I probe, I can get the why and when this portion of the code was put in place, a complete history lesson in the matter of a few minutes.

Figure 2. With an average of 142 inspections per month, it is quite clear that working efficiently is very important for an inspector. Some respondents reported more than 300 inspections per month.


Individuals that have these abilities did not get there overnight. They didn’t wake up one morning, implant the NEC chip in their head, and become this wealth of information. They worked for it. This is from years of walking various structures, researching and living their trade. At some point in time, they were new to this business and the code book seemed impossible. I have spoken to many electrical inspectors in hopes of creating an article that would be enlightening to some on the inspection itself. Just like the person who can spew code articles and sections, these individuals devour a structure in a way that leaves no stone unturned. It is second nature and, again, it didn’t happen overnight. Today’s "Safety in Our States” will share the results of my survey and hopefully plant seeds, lay the foundation so to speak, for future dialog on this topic. After all, this is yet one more benefit of your IAEI membership. If you are a new inspector, you are among the best. Take advantage of those who have been in the business for years and are darn good at it.

Insight from the survey

As you review the tables in this article for some of the results of this survey, it should be clear that this is just the tip of the iceberg. There is a huge opportunity in the area of providing organized materials around guidance and tools related to conducting an inspection. In researching for this article, I found that the resources for new inspectors are minimal at best. That being said, there was one common message that I heard. Inspectors were clear that the primary source of education for conducting inspections is in their IAEI membership, the contacts they have made. This is the unmeasured value of your IAEI membership and attendance of local, state, and section meetings. Never underestimate the value of your membership. Usually we tend to measure value in how much we saved on books and on training or other tools. It’s usually where we can affix a dollar amount to what we receive. What we sometimes fail to realize is the hidden value that you cannot measure. When it comes to educational material, I could argue that more learning occurs around a coffee pot and a water fountain than you could possibly imagine. It’s that quick conversation, that aha moment, which is your IAEI membership delivering the value to which it is impossible to affix a price tag.

Figure 3. Survey respondents were nicely distributed representing a wide range of experience (108 of the respondents to this survey answered this question).


After sifting through the results of this survey, I can conclude that there is more work to be done. There was one specific question that was asked to which this article does not share the results. The question was pertaining to what specific technique inspectors use while inspecting a structure and what educational classes have been taken. The responses varied considerably. The message received loud and clear was that an inspector should have a process and be consistent. Keep your eyes on this column for more on this topic as I will be probing deeper on this topic.

Sharing words of wisdom

I will leave you, the reader, with the following words of wisdom left by the electrical inspectors responding to this survey. I hope that these quotes spur more discussion and debate on this topic. There is a huge opportunity to provide those tools necessary for young and new inspectors coming in to this trade. IAEI is the resource for this knowledge.

"Keep an open mind. The code book offers many routes to a code-compliant installation. Just because you haven’t seen it before doesn’t mean that it defies the Code.”

Figure 4. NEC-2008 was most popular in this survey. We will begin the 2011 NEC adoption cycle across the U. S. and there are still some areas on the 2002 version of the NEC. One respondent reported that his jurisdiction will be on NEC-2011 beginning January 1, 2011. Some jurisdictions inspect to more than one version of the NEC, for example a respondent from Texas indicated he inspects to the 2002, 2005, and 2008 versions of the NEC.


". . . develop a process for specific types of inspections and use the same process every time. That should minimize the chance of missing components of the inspection that are important.”

". . . Dress the part . . . Wear a shirt and a tie and look the part!”

"Learn the Code and verify your code violations. Don’t go by memory or by what you think is in the Code. I think a checklist would be very valuable to those starting out.”

"Listen before you talk and ask questions before deeming something is non-compliant, you may not be seeing the full picture. Realize that you do not know everything in the Code; even experts disagree on the correct interpretation of the Code. Do not discount the knowledge of your customers (contractors). . . . Remember to communicate. When you listen to a different opinion you will learn. The object is education, either you educate the contractor or the contractor can educate you; both are win/win. You earn the respect of your customer as someone willing to listen and work with and not to be feared.”

Figure 5. Commercial and residential inspections topped the charts, but hospitals and high-rise buildings were not too far away. Inspections on each of these types of facilities are going to vary. Know the structure you are going to inspect, as what you may be looking for will probably be different. A few respondents noted that they will do some research before going to the inspection.


"Join the IAEI and talk to experienced inspectors.”

"Do not be in a hurry. If something looks questionable, then cite it; a retraction, if you are in error, can always be withdrawn.”

"Be consistent, be comprehensive, be accurate, and be respectful.”

"Know the electrical code. Have experience with the installations. Be at or above the level of knowledge of those you are inspecting.”

"Enforce the code to individuals with the same respect and foresight that you would in justifying yourself to a judge and a twelve-person jury.”

"Take all the time you need; don’t get in a hurry.”

Figure 6. Checklists are quite controversial for various reasons. One hundred ten respondents to this survey answered this question. Fifty-eight of them have used a checklist in the past but only 22 still include a checklist as part of their work.


"Be firm and fair and consistent.”

"If you don’t know something, don’t bluff your way through it. Tell them you will research it and get back to them.”

"Know the electrical code and how to apply it. Know how electrical systems are installed and work.”

"Slow down…. Do not allow yourself to be distracted by individuals while making your inspection.”

"Leave it better than you found it.”

"Conduct yourself in a professional matter.”

"Be calm, be patient and, most of all, remember it’s not personal.”

"Ask questions! If you get asked a question in the field and you are not sure of the answer, tell them you will get back to them after looking it up; you are not required to have the code memorized. A right answer is better than a guess. If you have never performed a job (hazardous, high voltage, etc.), when you have a contractor you can trust, pick their minds. You both learn from it. At field evaluations, talk to the person doing the field evaluations; find out what different standards allow. Be willing to learn, even from the electricians. Remember, no one is perfect. Do not be afraid to admit you made a wrong call.”

Table 1. Only 75 respondents indicated the state in which they reside. Thank you to everyone who participated.


"Study and attend meetings pertaining to the NEC.”

"Do not forget when you were on the other side of the fence.”

"Be accurate and know the code!”

"Go through the code book and make a list of what you are looking for on each job.”

"Take your time and don’t get in a hurry. Always check grounding and bonding.”

"Do not try to memorize the code, just learn to use it.”

"When issuing a correction notice, always cite the code violation with code sections. Never say that this is the way YOU want it. Be courteous and confident. Show respect and you will get respect.”

"Serve an apprenticeship with an experienced inspector.”

"Be sure the violations you write up are valid. Cite the code section and issue. Do not slip above the minimum standards of the NEC.”

"Know the code and understand each inspection. There is a lot of interpretation.”

"Take notes — document everything.”

"Always study the NEC article that pertains to what you are looking at. You will discover that it takes 4–5 years’ experience before you really feel comfortable in your inspection process. Always keep an open mind and use some common sense; never forget you are a public servant in this endeavor, not the electric sheriff.”

Table 2. It is clear from these results that this question should be a survey unto itself. The question was not formulated in such a manner as to stimulate the reviewer. A future article just may be in order to dig deeper in this area.


"You can’t know everything, especially at first, but use as many timesaving tools as possible; and attend IAEI meetings and training as often as possible. Through all my years in an apprenticeship, as a journeyman and as an electrical contractor, I did not learn as much as I have by attending IAEI meetings.”

"Purchase a NEC Handbook and read the commentary. There is always more than one interpretation of what is written, but stay consistent and treat everyone equally. Strict but fair. Be an educator and moderator.”

"Don’t be afraid to ask questions of the electricians or your supervisor, as nobody can keep all this stuff straight when it may have been years since you last saw a certain situation.”

"Look at each jobsite individually. Do not attempt to judge a job by the installer.”

"Slow down, stay calm. Take the job in small parts and not as a big project, it can become overwhelming.”
"You don’t have to worry about learning the code it will come with experience, work more on how you treat the people you’re working with (like you would want to be treated).”

"Look at code issues in relation to safety first and installation second. Also be on time and organized and willing to listen and educate your inspection clients.”

"The job is not about inspector vs. contractor. They are our customers and the first thing you should learn is customer service. Without contractors, we would not have a job. Our primary focus should be on electrical safety, but we must be able to point out violations in a way that is palatable to our customers. We can all learn from each other; and the first guy you meet that thinks he knows everything, you should run from him. He will be the one that gets someone hurt.”

"Do a ride along with other inspectors to see how they do it or more. Just to see how each looks at a job and how problems are worked out.”

"It’s simple, ‘Most anyone can read a book and regurgitate the requirements, but a true professional inspector knows his customer and gets his message across without overpowering or belittling the customer.’”

"Challenge yourself with thought-provoking questions regarding code requirements and hunt for the answers in the code book—you’ll learn so much!”

"Recognize that you have limitations with your knowledge and don’t be afraid to seek assistance. Membership in IAEI gives you unlimited access to industry experts to answer those unique, one-of-a-kind scenarios. Be firm, fair, and factual in your approach to inspections—most of all, be diplomatic.”

"Don’t just look at an electrical installation, trying to find code language that makes it in violation of the code; but rather look for proper interpretation and all exceptions that would make the installation code-compliant.”

"Keep a safe distance from arc flash potential. Study the codebooks and workbooks. Discuss things with electricians and other inspectors.”

"Know the code and be able to explain, in a nice way and with patience, what the code requirement is and why it is important.”

"Be as thorough as you can be, and document all corrections and send a copy—not just a phone call—to installers. I keep a copy of all inspection reports, and it has helped me when an issue arose a year later.”

"Ask yourself, before writing up a violation, two questions: What is the hazard? and Am I exercising common sense?

"Make sure that there isn’t any power on what you are inspecting.”


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Tags:  January-February 2011  Safety in Our States 

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Grounding Resistance and Spacing of Ground Rods

Posted By Leslie Stoch, Saturday, January 01, 2011
Updated: Wednesday, September 05, 2012

As we already know, the Canadian Electrical Code requires a minimum distance of 3 m between ground rods forming an electrical system grounding electrode. Why? This article discusses the reasons for this code requirement.

As everyone knows, Rule 10-700(2) specifies that a rod grounding electrode (with a few exceptions) must consist of at least two ground rods driven a minimum of 3 m apart. And for high voltage substations, Rule 36-302(1) also requires that every station must be grounded with at least four ground rods, not less than 3 m long, spaced a minimum distance of one rod length apart. Why does spacing between ground rods matter? What would be the problem if ground rods were to be more closely spaced?


Our story begins with the grounding resistance of every grounding electrode, which has three components:

  1. the resistance of the metal ground rods, grounding conductors and connections;
  2. contact resistance between the grounding electrode and the earth; and
  3. the resistance of the earth.

As it turns out, the first two are relatively small and can usually be considered insignificant when considering total grounding resistance. Grounding resistance can be considered as mainly the resistance of the earth.

To help us grasp the idea of grounding resistance, let’s assume that the earth around a single ground rod is made up of a series of concentric, equally spaced shells. The nearest shells have the highest resistances to current flow since they have the smallest cross-sectional areas and volumes. The shells further from the ground rod are larger and therefore have lower resistances. Therefore, when ground current flows away from the ground rod, through the earth, Ohm’s Law tells us that the shells nearest the rod will have higher voltage rise than those further from the rod.

Tests have shown that the earth within the first few cm of a ground rod will have the highest resistance and the highest voltage rise during a ground fault. Since the resistance of the earth near each ground rod will be very high, adding a second ground rod will not reduce the overall grounding resistance by very much unless the rod is located some distance from the first. Driving the rods close together will result in a high mutual resistance and the current flowing from each will raise the ground potential of the other.

For the above reasons, rods must be spaced far enough apart so as to avoid the effects of the higher resistance shells, so that the voltage rise around each does not affect the other. We don’t need to look very far for further proof. Measurement of grounding resistances at various distances from a grounding electrode have shown that approximately the following percentages of the total grounding resistance will occur at the following distances from the rod:

  • 25% of total at .03 m
  • 52% of total at .15 m
  • 94% of total at 3.0 m
  • 100% of total at 7.6 m

This tells us that ground rods would need to be spaced 7.6 m apart to achieve the best grounding effect. Obviously, the 3 m rule provided by the Canadian Electrical Code is a compromise, good but not perfect.

Other available data also supports these findings. Question – if we know the grounding resistance of a single ground rod (say 25 ohms), and we want to reduce the resistance by adding a second rod spaced in accordance with the CEC, will this reduce grounding resistance to 50%? Actually, no. It will only reduce the total grounding resistance to 25/2 x 1.16 = 14.5 ohms. The result of adding two rods will be 25/3 x 1.29 = 10.75 ohms. Multiplying factors for multiple rod arrangements are available.

As with previous articles, you should always consult the electrical inspection authority in each province or territory for a more precise interpretation of any of the above.


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Main protective and control devices for emergency generators — are we consistent on this issue?

Posted By Ark Tsisserev, Saturday, January 01, 2011
Updated: Wednesday, September 05, 2012

Let’s say, you are a supplier of an emergency generator or a designer of an emergency distribution system, and your task is to select an emergency generator and main disconnecting means and overcurrent devices that will manually or automatically disconnectthe electrical system supplied from the emergency generator.

The question is, Must the generator be provided with a singleprotective and control device?

This innocent question appears to create lots of confusion for the suppliers of emergency generators, electrical designers and electrical safety regulators; and the approach to this issue in the industry is far from being consistent.

Perhaps, the best place to find the answers is the Canadian Electrical Code — the standard for the electrical installation criteria.

Our first stop would be Section 28, as this section covers motors and generators. Rules 28-900 – 28-908 govern protection and control of generators, and it would beseemed logical to seek the answer within these rules. We may consider ourselves lucky, as the very first rule in this subsection (Rule 28-900)deals with disconnecting means required for generators.

This rule in part states that, "Generators shall be equipped with an indicating switch or circuit breaker by means of which the generator and all protective devices and control apparatus are able to be disconnected entirely from the circuits supplied by the generator…”

So, the issue appears to be solved, and the answer to our question above is deemed to be "Yes.”

But let’s take a deep breath and review the requirement mandated by Rule 28-900.

First of all, thisrequirement relates to generators in general, and it does not necessarily deal with an emergency generatorthat is governed by Section 46 of the CE Code.

Secondly, the requirement of Rule 28-900 appears to be inconsistent with the scope of the CE Code, as it does not deal with the installation criteria but seems to coverrequirements of "approved” product installed under rules of the Code.This latter observation means that Rule 28-900 does not appear to belong to the installation Code, as installation Code covers only installation of "approved” equipment. This also means that if a generator is, indeed, required to be equipped with "an indicating switch or circuit breaker,” such requirement should be in the CSA safety standard C22.2 No.100 that covers design and constructionof motors and generators.

S/C responsible for Section 28 has acknowledged this inconsistency, and the proposal to modify this requirement is currently being deliberated by this S/C.

Therefore, the answer to our question posed at the outset of this article has not been provided as yet.

Now is the time to make the second stop — Section 46. This section covers installation criteria forsources of the emergency power supplymandated by the National Building Code of Canada for life safety systems. Life safety systems are defined in Section 46, and this article is not intended to dwell on this matter. For the purpose of our discussion, the important fact is that Rule 46-202(3)(c) states that where a generator is utilized as a source of required emergency power supply for life safety systems, then such generator mustconform to the CSA standard CAN/CSA C282.

Before we’ll review this standard, let’s look at another provision of Section 46 in respect to the overcurrent device for an emergency power supply.

This next step will lead us to Rule 46-206(1). This rule states that "the overcurrent device for an emergency power supply shall be coordinated with the overcurrent devices of feeders and branch circuits supplying life safety systems and other electrical equipment connected to the emergency power supply in order to provide selective operation of the branch circuit overcurrent device when a fault occurs in that branch circuit.” If we’ll review this statement carefully, and if we’ll check out figure 8 in Appendix B Notes on Section 46 (page 430 of the CE Code), we’ll acknowledge that this rule does not specifically mandate the installation of the overcurrent device for an emergency power supply (as this O/C device may be mandated by the CSA standard C282). This rule simply states that the O/C protective device for an emergency generator must be coordinated with downstream O/C devices installed in accordance with the CE Code. And such coordination is required only between the emergency generator O/C device and O/C devices installedin feeders and branch circuitsthat supply life safety systems connected to the emergency generator. Figure 8in Appendix B Notes on Section 46 also appears to explain that the single O/C device for an emergency generator (which must be coordinated with the O/C devices of downstream feeders) is outside the scope of the Code, as it is a part of an emergency generator in accordance with provisions of the CSA standard C282.

But before we’ll move to this standard, let’s take a look at the CEC generic requirements in respect to protective and control devicesat any point of supply.

Section 14 of the CE Code is the place for these requirements. Rule 14-010 of the Code provides general criteria for such protective and control devices. This rule mandates that unless specifically indicated in the Code, all "electrical apparatus and ungrounded conductors” must be providedwith:

(a)automatic devices that open the electrical circuit when the current in the circuit "reaches a value that will producea dangerous temperature in the apparatus or conductor” or "in the event ofa groundfault”; and

(b) manual devices that "will safely disconnect all ungrounded conductors of the circuit at the point of supply simultaneously.”

Another rule of Section 14 could be appropriate for reviewof the O/C protection requirements of conductors. This rule is 14-100. It states in part that "each ungrounded conductor shall be protected by an overcurrent device at the point where it receives its supply of current…”

Thus, from the CE Code perspective, it is abundantlyclear that a single protective and controldevice must be provided at the point of supply.

Now is the perfect time to evaluate C282 provisions on this subject.

Subsection 8.7 of C282 is dedicated to "overcurrent devices” under scope of this standard.

Clause 8.7.1 of this Subsection states in part that "the overcurrent devices in the emergency distribution system shall be coordinated to maximize the selective tripping of branch circuit breakers when a short-circuit occurs.” This clause does not appear to specifically mandate a single disconnecting means/overcurrent protective device for an emergency generator, but simply requires coordination between the O/C devices in the emergency distribution system. This requirement is consistent with Rule 46-206(1) of the CEC, as was discussed earlier.

However, Clause 8.7.2 of this subsection states the following: "A lockable automatic device shall be used to disconnect the generator from the loads in the event of a fault current. The minimum rating of the automatic device(s) shall be equal to the full current of the LTP rating.”

This is interesting…..and a bit confusing. Does the wording of Clause 8.7.2 imply or direct a standard user that there can be only one main disconnect (i.e., breaker) device on an emergency generator?

Let’s review this latter requirement of C282 in light of the earlier observations. Based on the provisions of the CEC quoted above, it is clear that a single set of control devices must be provided with an emergency generator. Another piece of relevant information could be found in the ULC standard S524. Article 3.2.4 of this standard covers requirements for an emergency power supply derived from an emergency generator. Clause 3.2.4.3 of this article mandates that "the disconnecting means for a generator emergency power supply” must be fitted with a locking device. This requirement of the ULC S524 indicates that each generator conforming to C282 and intended to provide an emergency power supply source to a fire alarm system must be equipped with the disconnecting means.

Therefore, the logical conclusion based on this discussion is that an emergency generator must be provided with a single protective and control device.

Now is the time to support this conclusion by recommendation to amend Clauses 8.7.1 and 8.7.2 of C282.

Such recommendation has been sent to the technical committee responsible for the development of C282.

Meanwhile, as usual, the regulatory bodies with jurisdictional power must be consulted in order to clarify this subject.


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Tags:  Canadian Perspective  January-February 2011 

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Is it permissible to stub up conduits into the bottom of a stationary generator enclosure and continue the conductors out of the conduit directly into the generator itself, or...

Posted By Underwriters Laboratories, Saturday, January 01, 2011
Updated: Wednesday, September 05, 2012

Question

Is it permissible to stub up conduits into the bottom of a stationary generator enclosure and continue the conductors out of the conduit directly into the generator itself, or do I need to continue the conduit to the generator termination box?

Answer

It is permissible to stub up conduits into a generator enclosure and have exposed conductors inside of the generator enclosure provided that the generator is mounted on a non-combustible surface such as concrete. Stationary generators are evaluated for compliance with the Standard for Safety for Stationary Engine Generator Assemblies UL 2200 and Listed under the product category Stationary Engine Generators (FTSR), located on page 150 in the 2010 UL White Book. You can also access the Guide Information for FTSR on UL’s Online Certification Directory at www.ul.com/database and enter FTSR at the Category code search field.

UL 2200 requires that engine generators be provided with a complete enclosure. The bottom of the enclosure can be mounted on a non-combustible surface such as concrete, similar to an open bottom switchboard. Conduit stubs ups into the enclosure may expose conductors within the enclosure; however, connection to the generator terminations box must be in compliance with the installation instructions and the NEC and be accessible to the AHJ for inspection.


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Tags:  January-February 2011  UL Question Corner 

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