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2005 NEC Changes Summary Articles 700 through 702

Chapter 7 Special Conditions

Chapter 7, which covers special conditions, is the third of four chapters that deal with special topics. Chapters 5, 6, and 8 cover special occupancies, special equipment and communications systems, respectively. Remember, the first four Chapters of the NEC are sequential and form a foundation for each of the subsequent four Chapters.

What exactly is a "special condition?" It's a situation that doesn't fall under the category of Special Occupancies or Special Equipment, but creates a need for additional measures to ensure the "safeguarding of people and property" mission of the NEC put forth in Article 90.

The NEC groups these logically, as you might expect. Here are the general groupings:

  • Emergency and standby power systems. Articles 700, 701 and 702. Article 700 addresses emergency standby systems, Article 701 addresses legally required standby systems, and Article 702 addresses optional ones.
  • Interconnected power sources. Article 705. This primarily has to do with generators or photovoltaic systems used for onsite power generation.
  • Low-voltage, low-power wiring. Articles 720 - 780. Examples include control, signaling, instrumentation, fire alarm systems, and optical fiber installations.

ARTICLE 700 Emergency Power Systems

In a few cases, an emergency system simply provides poer for exit lighting or the illumination of exit signs upon loss of main power or in the case of fire. Its purpose isn't to provide power for normal business operations, but rather to provide lighting and controls essential for human life.

These systems are legally required, often as a condition of an operating permit for a given facility based on its use. The authority having jurisdiction makes the determination as to whether an emergency system is necessary for a given facility and what it must entail.

This background information will help you understand that not all emergency actions to save human life will fall under Article 700. The general goal is keep the emergency operation as reliable as possible. One way to do that is to use inherently safe actuation devices, such as valves that go to a predetermined position upon loss of power. Another is to limit what needs to be an emergency load in the first place so the emergency system powers only what is needed to save human life.

In an emergency, it's difficult to administratively control loads. Thus, the emergency system must be able to supply all emergency loads simultaneously. When the emergency power source also supplies power for load shedding or other nonemergency loads, the emergency loads take priority over the other loads, and those other loads may be dropped to support the emergency loads.

As you study Article 700, keep in mind that emergency systems are essentially lifelines for people. The entire article is based on keeping those lifelines from breaking.

  • Text revised to clarify the conditions when a single generator is permitted to supply emergency, legally required, and optional standby system loads.
  • The overcurrent protective device of an emergency power system must now be selectively coordinated. This means that circuit protection schemes confine the interruption to a particular area rather than to the whole system. For example with selective coordination, if a short circuit or ground fault occurs in a branch circuit, the only protection device that will open will be the one protecting just that branch circuit. Without selective overcurrent protection coordination, the feeder circuit protection device might open, leaving the entire system without power!

ARTICLE 701 Legally Required Standby Power Systems

In the hierarchy of electrical systems, Article 700 Emergency Systems get first priority. Taking the number two spot are legally required standby systems, which fall under Article 701.

The main difference between the two is that the emergency systems of Article 700 take priority over the legally required standby systems of Article 701. But there are other differences. For example, legally required systems must supply standby power in 60 seconds or less after a power loss, instead of the 10 seconds or less required of emergency systems.

Article 701 systems do not serve the purpose of directly protecting human life. They supply specific loads that, if shut down, would create hazards or impede rescue operations. Thus, hospital communications systems fall under Article 701-evacuation instructions announced over the public address system are part of a rescue operation.

Article 700 basically applies to systems or equipment required to protect people who are in an emergency and trying to get out, while Article 701 basically applies to systems or equipment needed to aid the people responding to the emergency. For example, Article 700 lighting provides an exit path. But, Article 701 lighting might illuminate the fire hydrants and switchgear areas.

  • Text revised to clarify when a single generator is permitted to supply legally required, and optional standby system loads.
  • The overcurrent protective device of a legally required system must now be selectively coordinated. With proper selectively coordinated overcurrent protective devices, a fault in the legally required system will be localized to the overcurrent protective device nearest the fault. This allows the remainder of the system to continue to function.

ARTICLE 702 Optional Standby Systems

Taking third priority after emergency and then legally required systems, optional standby systems protect public or private facilities or property where life safety doesn't depend on the performance of the system. These systems are not required for rescue operations.

Suppose a glass plant loses power. Once glass hardens in the equipment-which it will do when process heat is lost-the plant is going to suffer a great deal of downtime and expense before it can resume operations. An optional standby system can prevent this loss.

You'll see these systems in facilities where loss of power could cause economic loss or business interruptions. Data centers can lose millions of dollars from a single minute of lost power. A chemical or pharmaceutical plant could lose an entire batch from a single momentary power glitch. In many cases, the lost revenue cannot be recouped.

When the power went out in Chicago in August a few years ago, restaurants lost millions of dollars in food inventory due to a loss of refrigeration. But many firms were using optional standby systems and didn't suffer such huge losses. In an extended outage, where the logistics of fuel delivery becomes a problem, optional standby systems would have to wait in line behind legally required standby systems, which would have to wait in line behind emergency systems.

  • A new exception exempts transfer equipment for the temporary connection of a portable generator, but only under restricted conditions.
  • New section added to coordinate the disconnecting means requirements between emergency, legally required, and optional standby power systems.

Mike Holt's Comment: If you desire more information about any of the above changes, be sure to order my Changes book and/or library (Video/DVD).

12a. NEC Code Changes Textbook
Mike Holt’s Illustrated Changes to the NEC 2005 textbook is here! So, get ready now!

The 2005 NEC is here and its time to adapt. Don’t let the scale of this change intimidate you. With Mike Holt’s Illustrated Changes to the NEC 2005, you’ll be up-to-speed in no time. Nearly 5,000 changes were proposed for the 2005 NEC! Over 225 of them will have a significant impact on designing, installing and inspecting electrical systems. Mike takes you through these changes, which he considers to be of critical importance. You’ll be able to easily gauge how these changes will impact your work and apply them instantly. This 120-page comprehensive full-color textbook includes 198 color illustrations for reference. Subjects include: General Requirements, Circuits and Protection, Grounding versus Bonding, Wiring Methods, Equipment for General Use, Special Occupancies, Special Equipment, Special Conditions, and Limited Energy and Communications Systems.

Why does Mike’s book give you an edge? Because of the extra effort put forth to organize these changes in an easy-to-follow manner. Each change includes:

  • Cross references to other related Code requirements to help you develop a better understanding of how the Code rules relate to one another.
  • Background information for each change along with explanations, which are delivered in Mike’s trademark style… easy-to-understand.
  • Author’s Comments – These sections were written by Mike to help you better understand the NEC material, and to bring to your attention things he believes you should be aware of.
  • Full-color detailed graphics to reinforce those difficult concepts and provide instant understanding.

Product Code: 05BK
ISBN: 1-932685-27-8
Pages: 120
Illustrations: 198

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