IAEI News – January/February 2010 Digital Edition
January-February 2010
Not just in print, the current issue of IAEI News is also available online.
January/February 2010 is available now for you to flick through from cover to cover online! Try it out and give us your feedback. We would love to know what you think.
But remember, you can’t collect a website…
Edited on February 3, 2010 to fix link.
(No Ratings Yet)Are We Really Ungrounded?
Well?...
If you were to open an unopened jar, does that jar still qualify as “unopened”? No one would argue the fact that the moment I lock an unlocked door, that door is no longer “unlocked.” I must confess that this author has yet to come across an uneaten piece of cake and left that cake “uneaten.” So why do we consider an ungrounded system “ungrounded” when we are required to establish and connect a grounding electrode system to that ungrounded system? There seems to be a great misconception in both the installation and the enforcement of ungrounded systems as to the requirements for establishing a grounding connection at an ungrounded system. The fact of the matter is that there is nothing “ungrounded” about an ungrounded system. We are required to establish a grounding electrode system at the first means of disconnect to put the cabinets and other metallic equipment at earth’s voltage potential. Then we extend that grounded connection to the last point of the system through our equipment grounding conductors (see the definition of “grounded” and “bonded”). This equipment grounding connection is also the path we provide for clearing any ground faults likely to be imposed. Without a grounding electrode/equipment grounding system at this ungrounded system, we would have to rely on the earth as our fault return path which is prohibited by 250.4(A)(5) for grounded systems and prohibited for ungrounded systems by 250.4(B)(4). The component that is missing from an ungrounded system compared to a grounded system is the intentionally grounded conductor.
(No Ratings Yet)When is a sign not just a sign?
Rialto theater
Today’s demand for attention has brought on the need for signs to be more than just a display. Theses signs are designed for the potential customer to notice them and come in to check out the establishment. The sign might be portraying a message. Or it could be a show in itself. Let me take you on a quick step-by-step tour to inspecting signs.
Be aware of the codes
First, we inspectors need to be aware of the codes that affect the installation of signs (NEC Article 600), but also we might have other issues involved. Locally, one of the sign shops was contracted to recreate a theater marquee (see figures 1 and 2). This now incorporated some unique design criteria—such as luminaires, controllers, fluorescent cabinets, neon power supplies, and display lamps—and included compliance with additional code articles.
(No Ratings Yet)Standby and emergency power supply. Is there a difference?
Let say, a designer decides to install a backup power supply for the IT network in the office, or to provide an alternate source of power to the sump pump in a building. Or a decision is made to have a standby power source for lighting in all classrooms of a high school. Or what if a backup power supply is provided for all building exhaust, makeup fans and fans used for smoke control and smoke venting? And what about the same approach to the elevators or fire pumps? And how about the standby power intended for emergency lighting in exits or in corridors used by the public? And to make it fun, let’s even consider a backup power supply to a typical house. What kind of power supply sources should be used to provide a standby power supply to all these loads?
(No Ratings Yet)Safely Harnessing the Sun’s Energy
Photo 1. The photovoltaic system located at the Electrical Training Institute of Southern California generates sufficient power to meet most of the energy needs of the entire 144,000-square-foot ETI training facility, and serves as a hands-on training tool for apprentices, journeyman electricians, and contractors. Photograph from NECA; reprinted by permission.
Across the country and around the world, harnessing energy from the sun is becoming increasingly achievable for homeowners, businesses, and utilities alike. With an increased interest in solar photovoltaics (PV), comes a plethora of opportunities, as well as some challenges for the electrical industry. Amidst all the excitement and advantages of getting connected to alternative energy sources, the same safety hazards to persons and property should be realized by electrical industry partners, and more importantly, by consumers. Many competing specialty contractors are clamoring to complete these installations, but they often lack adequate training and understanding of PV systems—and the electricity they create. Electricity is electricity. Whether it comes from solar panels, dams, wind turbines, or other generation sources, the electricity produced is the same—and needs to be handled by those who are trained in and understand electricity. PV systems are electricity-generating equipment and require the same safety, standards, and expertise as any other high-voltage electrical system.
Electrical Safety
PV systems generate electricity, and a lot of it. A typical PV system for home or business produces between 400 and 1000 volts dc, which, at those voltages, can be every bit as dangerous as alternating current systems. New applications for PV technology are emerging all the time (see photo 2).
(No Ratings Yet)The Evolution of Communications Circuits & the NEC
Photo 1. Satellite TV and Broadband Antenna
In the beginning Samuel Morse, in 1844, started the digital data communications industry with a 37-mile stretch of wire sending what became known as Morse code from Washington, D.C. to Baltimore. Remember the day?
In early copies of the National Electrical Code, Chapter 8 was entitled “Communications and Control Systems.” Included in this chapter were signal and control systems and radio equipment. Article 800, Signal and Control Systems, scope included electric circuits for transmitting intelligence including telephone, telegraph, district messenger, call bell, and went on to include low-voltage circuits such as temperature control. Article 810, Radio Equipment, scope included radio receiving equipment and amateur radio transmitting equipment.
(No Ratings Yet)NSF International Announces New Strategic Partnership with the Nation’s First Nationally Recognized Testing Laboratory, MET Laboratories
ANN ARBOR, Michigan — NSF International, a leading public health and safety organization that writes standards and certifies products for food, water and consumer goods, today announced a new strategic partnership with MET Laboratories, the first Nationally Recognized Testing Laboratory (NRTL) in the United States.
(No Ratings Yet)The Microinverter and the AC PV Module
Microinverters
No discussion of PV systems would be complete without a look at the newest inverter technologies that the installer and inspector will face. These new technologies include the microinverter and the AC PV module.
Microinverters
The inverters that have been covered in the past several issues are known as string inverters because they operate with a string of series connected PV modules. These inverters range in power from one megawatt down to about 700 watts. DC maximum system voltages can get as low as about 125 volts.
(No Ratings Yet)The Importance of the AHJ in Fire Pump Installations
Photo 1. As codes and standards get revised every Code cycle, evidence suggests that there is ever greater reliance upon the “AHJ Industry” for code compliance assurance. This is no more critical than in fire protection. This article draws attention to two requirements that affect reliability, safety and performance under fire conditions.
The services of the inspection community are of utmost importance to maximize safety and reliability. This is especially true when the inspector serves as the AHJ for the installation. This article addresses two such instances pertaining to fire pumps, one is covered by the National Electrical Code (NEC) in 695.4 and the other in the National Fire Protection Association (NFPA) Standard for the Installation of Stationary Pumps for Fire Protection, NFPA 20.
In the interest of maximizing reliability, NFPA 20 has always preferred the direct connection which is to bring the supply conductors directly to the fire pump controller as described in NEC 695.4(A). However, NEC 695.4(B) does permit a supervised “single disconnecting means and associated overcurrent protective device” installed in these supply conductors. Based on a recent revision in 9.2.3.4, NFPA 20 (2010), NEC 695.4(B), which is extracted out of NFPA 20, will require the overcurrent protective device to be rated based on the LRC (locked rotor current) of the fire pump motor. Additionally, per NEC 700.27, “Emergency system(s) overcurrent devices shall be selectively coordinated with all supply side overcurrent protective devices.” In other words, a pump room fault is to be cleared by the fire pump controller circuit breaker rather than by an upstream overcurrent protective device which may very well be inaccessible for reset or fuse change during a fire. It is important that this coordination is based on the recognition that the circuit breaker in the fire pump controller is “set” to trip differently from protection values contained in NEC 430 covering ordinary motor circuits. Section 10.4.3.3 of NFPA 20 (2010) provides the electrical characteristics of the circuit breaker contained in the fire pump controller as follows:
(No Ratings Yet)GFCIs – Where are they?
Photo 1. GFCI kitchen counter
The 2009 Canadian Electrical Code is peppered with references to, and requirements for ground-fault circuit interrupters (GFCIs). For very good reasons, GFCIs have become prevalent throughout many sections of the electrical code. And usually without our knowledge, they have no doubt prevented many injuries and saved many lives. This article provides a summary of these CEC rules.
(No Ratings Yet)Stray Voltage — Catching What We Cannot See
Photo 1
“Where the cow won’t give milk anymore” is a standard lyric in old classic country songs; perhaps you’ve wondered why. Well, back in the early days many strange and downright bizarre occurrences happened on the farm, most of which were thought to be the product of superstition, bad living or old wives’ tales; but that was before modern measuring equipment, grounding methodologies, equipotential planes, voltage gradient ramps (transition areas) and ensuring a low-impedance path to ground. Let’s compare what many have believed and what modern principles of electricity have proven to be the real culprit and, in many cases, the reason for these strange and often devastating occurrences that plagued many livestock farms in the U.S. and throughout the world.
In this article we will look at some of the effects of stray voltage and then see how we can try to mitigate those effects through a good understanding of the many sources of stray voltage and of how those voltages interact, along with the different degrees of sensitivity of not only animals but also humans to the flow of electrical current.
(3 votes, average: 1.00 out of 5)Circuit breakers and old panelboard; will anything work?
Question
I have an old panelboard made by a company that was sold and no longer produces panelboards or circuit breakers under their old name. How do I find circuit breakers listed for use in the panel when the manufacturer is no longer in business, can I use any circuit breaker that fits?
(No Ratings Yet)When is the UL White Book published every year?
(No Ratings Yet)
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