2008 NEC® Changes (Part 1)
NEC Digest®, October 2006 (necdigest®, National Electrical Code®, and NEC® are registered trademarks of the National Fire Protection Association, Inc., Quincy, MA 02169)
By James Stallcup, Sr. and Mark Ode
Editor’s note: James Stallcup Sr. and Mark Ode, two of the most knowledgeable and well-respected experts in the electrical industry, have teamed up to write a series of special Code Issues articles giving us the scoop on the most important upcoming changes for NEC 2008.
2008 NEC Products
This issue of the 2008 NEC changes covers the 25 most important changes to Article 100. Words that have been deleted are indicated by strikethroughs, while words that have added are underlined to help simply and clarify each change.
2005 NEC - Article 100
Bonding (Bonded). The permanent joining of metallic parts to form an electrically conductive path that ensures electrical continuity and the capacity to conduct safely any current likely to be imposed.
2008 NEC - Article 100
Bonded (Bonding). Connected to establish electrical continuity and conductivity.
Author’s Substantiation: This revision has been written to apply generally throughout the NEC and simply describe the purpose and function of bonding.
There are conditions in the NEC where specific bonding is required solely to minimize the difference of potential (voltage) between conductive components.
2008 NEC - Article 100
Branch-Circuit Overcurrent Device. A device capable of providing protection for service, feeder, and branch circuits and equipment over the full range of overcurrents between its rated current and interrupting rating. Branch circuit overcurrent protective devices are provided with interrupting ratings appropriate for the intended use but no less than 5,000 amperes.
Author’s Substantiation: A new definition has been added to clarify that a branch circuit overcurrent device is capable of providing protection for a service, feeder, and branch circuits.
2008 NEC - Article 100
Clothes Closet. A non-habitable room or space intended primarily for storage of garments and apparel. Author’s Substantiation: A new definition has been added to clarify what constitutes a “clothes closet.”
2005 NEC - 550.2
Manufactured Home. A structure, transportable in one or more sections, that is 2.5 m (8 body ft) (2.5m) or more in width or 12m (40 body ft) (12 m) or more in length in the traveling mode or, when erected on site, is 30 m2 (320 ft2) or more; which is built on a chassis and designed to be used as a dwelling, with or without a permanent foundation, when connected to the required utilities, including the plumbing, heating, air conditioning, and electrical systems contained therein. Calculations used to determine the number of square meters (square feet) in a structure will be based on the structure’s exterior dimensions, measured at the largest horizontal projections when erected on site. These dimensions include all expandable rooms, cabinets, and other projections containing interior space, but do not include inside bay windows.
For the purpose of this Code and unless otherwise indicated, the term mobile home includes manufactured homes.
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FPN No. 1: See the applicable building code for definition of the term permanent foundation.
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FPN No. 2: See Part 3280, Manufactured Home Construction and Safety Standards, of the Federal Department of Housing and Urban Development, for additional information on the definition.
2008 NEC - Article 100
Manufactured Home. A structure, transportable in one or more sections, that, in the traveling mode, is 8 body-ft (2.4 m) or more in width or 40 body-ft (12.2 m) or more in length or, when erected on site, is 320 ft2 (29.7 m2) or more and that is built on a permanent chassis and designed to be used as a dwelling, with or without a permanent foundation, when connected therein. The term manufactured home includes any structure that meets all the provisions of this paragraph except the size requirements and with respect to which the manufacturer voluntarily files a certification required by the regulatory agency, and except that such term shall not include any self-propelled recreational vehicle. Calculations used to determine the number of square feet (square meters) in a structure are based on the structure’s exterior dimensions, measured at the largest horizontal projections when erected on site. These dimensions include all expandable rooms, cabinets, and other projections containing interior space, but do not include bay windows.
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FPN No. 1: See the applicable building code for definition of the term permanent foundation.
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FPN No. 2: See Part 3280, Manufactured Home Construction and Safety Standards, of the Federal Department of Housing and Urban Development, for additional information on the definition.
Author’s Substantiation: This definition has been relocated from 550.2 to Article 100 to assist the user by providing consistent meaning of defined terms throughout the National Fire Codes.
2005 NEC - Article 100
Dwelling Unit. A single unit, providing complete and independent living facilities for one or more persons, including permanent provisions for living, sleeping, cooking, and sanitation.
2008 NEC - Article 100
Dwelling Unit. One or more rooms arranged for complete, independent housekeeping purposes, with space for eating, living, and sleeping; facilities for cooking, and provisions for sanitation.
Author’s Substantiation: This revision simplifies and clarifies what a dwelling unit is and meets the needs of the NEC, NFPA 1, NFPA 101, and NFPA 5000.
2008 NEC - Article 100
Electrical Power Production and Distribution Network. Power production, distribution, and utilization equipment and facilities, such as an electric utility system that delivers electric power to the connected loads, that is external to and not controlled by an Interactive System.
Author’s Substantiation: A new definition has been added to correlate with the definition in section 2.41 of Underwriter Laboratory Standard 1741 – Inverters, Converters and Controllers for Use in Independent Power Systems.
2005 NEC - Article 100
Equipment. A general term including material, fittings, devices, appliances, luminaires (fixtures), apparatus, and the like used as a part of, or in connection with, an electrical installation.
2008 NEC - Article 100
Equipment. A general term including material, fittings, devices, appliances, luminaires (fixtures), apparatus, machinery, and the like used as a part of, or in connection with, an electrical installation.
Author’s Substantiation: “Machinery” has been added to the definition to ensure that electrical machinery is included in the definition for electrical equipment.
Section 110.2 requires conductors and electrical equipment required or permitted by the NEC to be only acceptable if approved. Adding machinery will now make it clear that industrial equipment installations are covered by the NEC.
2005 NEC - Article 100
Ground. A conducting connection, whether intentional or accidental, between an electrical circuit or equipment and the earth or to some conducting body that serves in place of the earth.
2008 NEC - Article 100
Ground. The earth.
Author’s Substantiation: The definition of ground has been simplified by deleting the intentional or accidental connection to earth or to some body serving in place of the earth.
2005 NEC - Article 100
Grounding Electrode. A device that establishes an electrical connection to the earth.
2008 NEC - Article 100
Grounding Electrode. A conducting object through which a direct connection to earth is established.
Author’s Substantiation: The present definition for grounding electrode was rewritten to better describe its function. The grounding electrode establishes and maintains a direct connection to earth.
2005 NEC - Article 100
Grounding Electrode Conductor. The conductor used to connect the grounding electrode(s) to the equipment grounding conductor, to the grounded conductor, or to both, at the service, at each building or structure where supplied by a feeder(s) or branch circuit(s), or at the source of a separately derived system.
2008 NEC - Article 100
Grounding Electrode Conductor. The conductor used to connect the grounding electrode(s) to a system conductor or to equipment.
Author’s Substantiation: There are times where a grounding electrode conductor is connected to equipment, such as permitted where a supplementary electrode is installed in accordance with 250.54.
2005 NEC - Article 100
Grounding Conductor, Equipment. The conductor used to connect the non-current-carrying metal parts of equipment, raceways, and other enclosures and to the system grounded conductor or to grounding electrode conductor , or both, at the service equipment or at the source of a separately derived system .
2008 NEC - Article 100
Grounding Conductor, Equipment. The conductive path installed to connect normally non-current-carrying metal parts of equipment together and to the system grounded conductor or to grounding electrode conductor. FPN No. 1: It is recognized that the equipment grounding conductor also performs bonding. FPN No.2: See 250. 8 for a list of acceptable equipment grounding conductors.
Author’s Substantiation: This revision has been written to apply generally throughout the NEC and simply describe the purpose and function of the equipment grounding conductor.
2008 NEC - Article 100
Intersystem Bonding Termination. A device that provides a means of bonding communications equipment at the service equipment or the disconnecting means for any additional buildings or structures.
Author’s Substantiation: This new definition describes a device used to connect the communications equipment to the service equipment or the disconnecting means for additional buildings or structures in accordance with Part II in Article 225.
2005 NEC - Article 100
Luminaire. A complete lighting unit consisting of a lamp or lamps, together with the parts designed to distribute the light to position and protect the lamps and ballast (where applicable) connect the lamps to the power supply.
2008 NEC - Article 100
Luminaire. A complete lighting unit consisting of a light source, such as a lamp or lamps, together with the parts designed to position the light source and connect it to the power supply. It may also include parts to protect the light source, ballast, or distribute the light. A lampholder itself is not a luminaire.
Author’s Substantiation: The rewording of the definition clarifies the issue that a lampholder is clearly not a luminaire and the remainder of the text was for clarification.
2008 NEC - Article 100
Neutral Conductor. The conductor connected to the neutral point of a system that is intended to carry current under normal conditions.
Neutral point.The common point on a wye-connection in a polyphase system or midpoint on a single-phase, 3-wire system, or midpoint of a single-phase portion of a 3-phase delta system, or a midpoint of a 3-wire, direct current system.
FPN:At the neutral point of the system, the vectorial sum of the nominal voltages from all other phases within the system that utilize the neutral, with respect to the neutral point, is zero potential.
Author’s Substantiation: Added two new definitions to provide information on what constitutes a neutral and a neutral point. 2005 NEC - Article 100 Qualified Person. One who has skills and knowledge related to the construction and operation of the electrical equipment and installations and has received safety training on the hazards involved.
2008 NEC - Article 100
Qualified Person. One who has skills and knowledge related to the construction and operation of the electrical equipment and installations and has received safety training on to recognize and avoid the hazards involved.
Author’s Substantiation: Adding the phrase “to recognize and avoid” to the definition of qualified person provides a reason for the safety training.
2008 NEC - Article 100
Short-Circuit Current Rating. The prospective symmetrical fault current at a nominal voltage to which an apparatus or system is able to be connected without sustaining damage exceeding defined acceptance criteria.
Author’s Substantiation: Adding this definition provides a definition for the phrase used in 110.10 and various other locations in the Code.
2008 NEC - Article 100
Surge Protective Devices (SPDs). A protective device for limiting transient voltages by diverting or limiting surge current; it also prevents continued flow of follow current while remaining capable of repeating these functions and designated as follows:
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Type 1 -Permanently connected SPDs intended for installation between the secondary of the service transformer and the line side of the service disconnect overcurrent device.
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Type 2 - Permanently connected SPDs intended for installation on the load side of the service disconnect overcurrent device; including SPDs located at the branch panel.
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Type 3 -Point of utilization SPDs.
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Type 4 -Component SPDs, including discrete components, as well as assemblies.
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FPN No. 1:For further information on Type 1, Type 2, Type 3, and Type 4 SPDs, see UL 1449, Standard for Surge Protective Devices.
Author’s Substantiation: A new definition has been added to replace the term transient voltage surge suppressor used in 285.2.
2008 NEC - Article 100
Ungrounded. Not connected to ground or a conductive body that extends the ground connection.
Author’s Substantiation: The word “ungrounded” is used extensively in the NEC, previously without a definition.
2008 NEC - Article 100
Utility-Interactive Inverter. An inverter intended for use in parallel with an electric utility to supply common loads and sometimes deliver power to the utility.
Author’s Substantiation: The purpose of this change is to add a new definition of Utility-Interactive Inverter that will be used in Article 690, 692, and Article 705. Code Making Panel 13 should be given authority for this definition to appear in Article 100. The definition is the same as the definition in Section 2.4 of Underwriter Laboratory Standard 74, Inverters, Converters and Controllers for Use in Independent Power Systems. This new definition will be used in the definition of Interactive System used in Article 100, 690, 692 and Article 705. This change is being proposed as part of a rewrite of Article 690, 692 and Article 705 with respect to the interconnection of systems and equipment for use with distributed energy resources.
UL 74 is currently under revision with a title change from Inverters, Converters, and Controllers for Use in Independent Power Systems to Inverters, Converters, Controllers and Interconnection Systems Equipment Use with Distributed Energy Resources. However the definition of Utility- Interactive Inverter remains unchanged.
2005 NEC - 110.12
(A) Unused Openings. Unused cable or raceway openings in boxes, raceways, auxiliary gutters, cabinets, cutout boxes, meter socket enclosures, equipment cases, or housings shall be effectively closed to afford protection substantially equivalent to the wall of the equipment. Where metallic plugs or plates are used with nonmetallic enclosures, they shall be recessed at least 6 mm (1/ 4 in.) from the outer surface of the enclosure.
2008 NEC - 110.12
(A) Unused Openings. Unused openings other than those for the operation of equipment or for mounting purposes shall be closed to afford protection substantially equivalent to the wall of the equipment. Where metallic plugs or plates are used with nonmetallic enclosures, they shall be recessed at least 6 mm (1/ 4 in.) from the outer surface of the enclosure.
Author’s Substantiation: The change indicates all unused openings should be closed except for those required for the functional operation of the equipment or enclosure or for the proper mounting of such equipment or enclosure.
2005 NEC - 110.16
Flash Protection. Switchboards, panelboards, industrial control panels, meter socket enclosures, and motor control centers that are in other than dwelling occupancies and are likely to require examination, adjustment, servicing, or maintenance while energized shall be field marked to warn qualified persons of potential electric arc flash hazards. The marking shall be located so as to be clearly visible to qualified persons before examination, adjustment, servicing, or maintenance of the equipment.
2008 NEC - 110.16
Flash Protection. Electrical equipment, such as switchboards, panelboards, industrial control panels, meter socket enclosures, and motor control centers that are in other than one- and two-family dwelling occupancies and are likely to require examination, adjustment, servicing, or maintenance while energized shall be field marked to warn qualified persons of potential electric arc flash hazards. The marking shall be located so as to be clearly visible to qualified persons before examination, adjustment, servicing, or maintenance of the equipment.
Author’s Substantiation: One- and two-family dwellings do not normally have high enough flash hazards to require marking so this is a reasonable point of demarcation. Many multifamily dwellings have services that are large enough or are supplied from utility company power sources with high enough inrush current that a flash hazard exists and should be required to be field marked to indicate a flash hazard. Adding the words “electrical equipment” now requires flash protection marking for large fusible switches and similar electrical equipment where a flash hazard may exist, such as a 1600 fusible wall mounted switch.
2008 NEC - 110.20
Enclosure Types. Enclosures (other than surrounding fences or walls) of switchboards, panelboards, industrial control panels, motor control centers, meter sockets, and motor controllers, rated not over 600 volts nominal and intended for such locations, shall be marked with an Enclosure Type number as shown in Table 110.20.
Author’s Substantiation: Table 430.91, covering motor controller enclosure types, has been used by many Code users for enclosures for numerous kinds of equipment, even though it is stated in 430.91 that it only applies to motor controller enclosures. Moving the requirements of 430.91 and Table 430.91 into a general application area of the Code and specifically stating the kinds of equipment to which they apply, will add clarity.
2005 NEC - 110.22
Identification of Disconnecting Means. Each disconnecting means shall be legibly marked to indicate its purpose unless located and arranged so the purpose is evident. The marking shall be of sufficient durability to withstand the environment involved. Where circuit breakers or fuses are applied in compliance with the series combination ratings marked on the equipment by the manufacturer, the equipment enclosure(s) shall be legibly marked in the field to indicate the equipment has been applied with a series combination rating. The marking shall be readily visible and state the following:
CAUTION - ENGINEERED SERIES COMBINATION SYSTEM RATED _ AMPERES. IDENTIFIED REPLACEMENT COMPONENTS REQUIRED
FPN: See 240.86(B) for interrupting rating marking for end-use equipment.
2008 NEC - 110.22
Identification of Disconnecting Means. Each disconnecting means shall be legibly marked to indicate its purpose unless located and arranged so the purpose is evident. The marking shall be of sufficient durability to withstand the environment involved.
Where circuit breakers or fuses are applied in compliance with series combination ratings selected under engineering supervision and marked on the equipment as directed by the engineer, the equipment enclosure(s) shall be legibly marked in the field to indicate the equipment has been applied with a series combination rating. The marking shall be readily visible and state the following:
CAUTION - ENGINEERED SERIES COMBINATION SYSTEM RATED _ AMPERES. IDENTIFIED REPLACEMENT COMPONENTS REQUIRED
FPN: See 240.86(B) for interrupting rating marking for end-use equipment. Author’s Substantiation: The addition of the text in 110.22 for series-combination ratings selected under engineering supervision in existing installations provides coordination between Sections 110.22 and 240.86(A), where permission for series rated systems selected by calculation was added in the 2005 NEC.
2005 NEC - 110.26(C) Entrance to Working Space
(2) Large Equipment. For equipment rated 1200 amperes or more that contains overcurrent devices, switching devices, or control devices, there shall be one entrance to the required working space not less than 610 mm (24 in.) wide and 2.0 m (6 1/ 2 ft) high at each end of the working space. Where the entrance has a personnel door(s), the door(s) shall open in the direction of egress and be equipped with panic bars, pressure plates, or other devices that are normally latched but open under simple pressure.
A single entrance from the required working space shall be permitted where either of the conditions in 110.26(C)(2)(a) or (C)(2)(b) is met.
2008 NEC - 110.26(C) Entrance to and Egress from Working Space
(2) Large Equipment. For equipment rated 1200 amperes or more and over 1.8 m (6 ft) wide that contains overcurrent devices, switching devices, or control devices, there shall be one entrance to the required working space not less than 610 mm (24 in.) wide and 2.0 m (6 1/ 2 ft) high at each end of the working space. Where the entrance has a personnel door(s) that is less than 1.8 m (6 ft) from the working space, the door(s) shall open in the direction of egress and be equipped with panic bars, pressure plates, or other devices that are normally latched but open under simple pressure.
A single entrance to and egress from the required working space shall be permitted where either of the conditions in 110.26(C)(2)(a) or (C)(2)(b) is met.
Author’s Substantiation: The previous Code text appeared to only address the entrance into a working space. By adding “egress from the working space” there will be equal emphasis on permitting sufficient room leave the electrical equipment work space.
The new text clarifies that the personnel door(s) requirement for panic bars and similar hardware and the opening in the direction of egress applies to personnel doors that are less than 6 feet from the equipment working space. This requirement would not apply to doors located 6 feet or more from the working space.
This change effectively returns the requirement for large equipment to be considered over 6 foot in width, as well as being 1200 amperes or more. The over 6 foot requirement had been deleted for the 2005 NEC.
2005 NEC - 110.33 Entrance and Access to Work Space.
(A) Entrance. At least one entrance not less than 610 mm (24 in.) wide and 2.0 m (6 1/ 2 ft) high shall be provided to give access to the working space about electric equipment. Where the entrance has a personnel door(s), the door(s) shall open in the direction of egress and be equipped with panic bars, pressure plates, or other devices that are normally latched but open under simple pressure.
2008 NEC - 110.33 Entrance to Enclosures and Access to Working Space.
(A) Entrance. At least one entrance to enclosures for electrical installations as described in 110.31 not less than 610 mm (24 in.) wide and 2.0 m (6 1/ 2 ft) high shall be provided to give access to the working space about electric equipment. Where the entrance has a personnel door(s) that is less than 3.7 m (12 ft) from the working space, the door(s) shall open in the direction of egress and be equipped with panic bars, pressure plates, or other devices that are normally latched but open under simple pressure.
Author’s Substantiation: The change in this section requires at least one entrance to provide access to the working space for a high voltage enclosure as described in Section 110.31. The new text clarifies that the personnel door(s) requirement for panic bars and similar hardware and the opening in the direction of egress applies to personnel doors that are less than 12 feet from the equipment working space. This requirement would not apply to doors located 12 feet or more from the working space.
Continue to Part 2
Reprinted with permission from necdigest®, Copyright 2007, National Fire Protection Association, Quincy, MA 02169
necdigest®, National Electrical Code®, and NEC® are registered trademarks of the National Fire Protection Association, Inc., Quincy, MA 02169
