This article is Part 2 of a series that provides a concise and complete understanding of some of the significant changes that have been incorporated into the 2011 edition of the National Electrical Code (NEC). There were 5,077 Code change proposals and 2,935 public comments that the NEC technical committees acted on during the 2011 development process. This article does not present all of the 2011 Code changes, and the changes it covers are in the numerical sequence in which they appear in the NEC. Chapter 2 of the Code provides requirements related to wiring and protection and is so titled.
Chapter 2 Wiring and Protection
Section 200.4 Neutral Conductors (New)
Section 200.4 is new and provides users with text that prohibits the use of neutral conductors with more than one branch circuit, more than one multiwire branch circuit, or more than one set of ungrounded feeder conductors unless specifically permitted by other provisions in the NEC. Note that Section 215.7 permits the use of a common neutral for more than one set of feeder conductors as addressed in that particular rule.
Sections 210.8(A) and (B) Dwelling Units and Other than Dwelling Units (Revisions)
Ground-fault circuit interrupter (GFCI) devices, installed to comply with the requirements of 210.8, must be installed in a readily accessible location. This readily accessible requirement applies to GFCI devices installed in dwelling units and those installed in other than dwelling units.
Section 210.8(B)(8) Garages, Service Bays, and Similar Areas (New)
The addition in 210.8(B) of new list item (8) will now require that all 125-volt, single-phase, 15- and 20-ampere receptacles installed in “garages, service bays, and similar areas” be GFCI-protected.
Section 210.12 Arc-Fault Circuit Interrupter Protection (Revision)
The definition of the term “arc-fault circuit interrupter” has been relocated to Article 100. The use of metal-clad cable is now permitted where Exception No. 1 or Exception No. 3 are applied. Exception No. 1 has been modified to recognize the use of an outlet branch-circuit type AFCI at the first outlet. Exception No. 3 now requires an individual branch circuit. New AFCI provisions have been added to 210.12(B) to address branch-circuit modifications, replacements or extensions. A listed outlet branch-circuit AFCI is now permitted to be installed at the first receptacle outlet of an existing branch circuit to protect any modifications, replacements or extensions of that branch circuit.
Section 210.52(G) Basements, Garages, and Accessory Buildings (Revision)
All accessory buildings for a one-family dwelling unit, such as sheds, greenhouses, pool houses or pole barns, which are supplied with electricity, are now required to have at least one receptacle outlet in addition to those for specific equipment installed.
Section 225.70 Substations (New)
New requirements have been added to Article 225 to address the installation of substations on the load side of the service point. Previous editions of the NEC provided no requirements for installers or the authority having jurisdiction where a substation was installed on the load side of the service point. Additional changes to aid the Code user in this type of installation include a new Article 399, “Outdoor, Overhead Conductors, Over 600 Volts.” This new section, 225.70, is intended to address outdoor substations for outdoor branch circuits and feeders rated over 600 volts.
Section 230.40 Exception No. 4 (Revision)
New text added to 230.40 Exception No. 4 now permits a single service to supply the “house panel” required by 210.25 for multiple-occupancy buildings, two-family dwellings and multifamily dwellings.
Section 230.44 Cable Trays (Revision)
All cable trays containing service conductors are now required to be identified with permanently affixed labels. The label must include the wording “service-entrance conductors.” Wiring methods that are permitted to be installed in cable tray as service-entrance conductors are now in a user-friendly list format.
Section 230.72(A) Exception (Revision)
A new marking requirement has been added to the 230.72(A) Exception to identify the location of a service disconnect that is remotely located as permitted by this exception. This revision (in addition to the general rule of 230.72(A)) will now permit a disconnecting means used only for a water pump but intended to also provide fire protection to be located remote from the other disconnecting means. A plaque shall be posted at the location of the remaining grouped disconnects denoting its location.
Section 230.82(9) Equipment Connected to the Supply Side of the Service Disconnecting Means (New)
A new list item (9) has been added to 230.82 to permit the connection of listed communications equipment on the supply side of the service-disconnecting means where it is under the exclusive control of the serving electric utility and where suitable overcurrent protection and disconnecting means are provided. This new list item permits the use of new equipment and installations associated with smart grid applications and lifeline (e.g., emergency calling) communications equipment powered at the premises. This new provision allows equipment to be installed without a disconnecting means where the supply is installed as part of a meter socket, such that access can only be gained with the meter removed. This revision is necessary to allow for the safe operation and installation of a new generation of metering and communications equipment.
Section 240.15 Ungrounded Conductors (Revision)
The reference to 210.4(B) is deleted in 240.15(B)(1), as this section requires all ungrounded conductors with a means of simultaneous disconnect, and this section addresses protection requirements. The permission for protection of a multiwire circuit without handle ties is deleted. The requirements of 240.15(B)(2) are clarified to apply only to single-phase AC 120/240-volt circuits.
Section 240.87 Noninstantaneous Trip (New)
Section 240.87 is new and requires that, where a circuit breaker is used without an instantaneous trip, documentation be available and a means be provided to reduce the incident energy when justified energized work must be performed. Three methods to reduce the incident-energy levels are provided in this section, as follows:
1. Zone-selective interlocking that allows the upstream circuit breaker and downstream circuit breaker to communicate with each other, resulting in faster clearing time when needed
2. Differential relaying accomplishes the same goal by monitoring the amount of current through the upstream circuit breaker and the downstream circuit breakers
3. An energy-reducing maintenance switch allows the trip unit to be set on instantaneous whenever working within the flash-protection boundary and then turned back to the short time-delay mode when finished. Where an energy-reducing maintenance switch is provided, it must have a local status indicator to notify people of the position of the switch.
Section 240.91(B) Devices Rated Over 800 Amperes (New)
This new subdivision (B) in Section 240.91 permits conductors in circuits rated over 800 amperes to have overcurrent protection applied at values above their rated ampacity. This will apply only where the equipment is listed and marked for the application and within the limitations provided for supervised industrial installations, as follows:
1. The conductors are protected within recognized time versus current limits for short-circuit currents.
2. Where all equipment in which the conductors terminate is listed and marked for the application
Section 250.2 Supply-Side Bonding Jumper (New)
A new definition that applies specifically to bonding jumpers on the supply side of services or separately derived systems has been added to 250.2. The new term has also been incorporated within Article 250 as appropriate and provides users with specific guidance to sizing rules directly related to equipment bonding jumpers installed on the supply side of a service or separately derived system.
Section 250.21 Ungrounded Systems (Revision)
Section 250.21(B) has been restructured into a list format and revised to require the sensing devices for ground-fault detection equipment to be installed as close to the source as practicable. A new subdivision (C) has been added to this section and provides a requirement to mark ungrounded systems at the service equipment or source equipment.
Section 250.30 Grounding Separately Derived Systems (Revision)
This section has been revised to provide a more logical order and layout. Section 250.30(A) and (B) were revised to include both editorial and technical revisions. The term “equipment-bonding jumper” has been changed to “supply-side bonding jumper” in Section 250.30(A)(2). The system-bonding jumper for a separately derived system must now remain within the enclosure where it originates. Section 250.30(C) is new and covers outdoor sources. New subdivision (C) requires a grounding-electrode conductor connection to be made outside if the separately derived system is installed outside the building. Two new informational notes have been added following the driving text in 250.30 and provide information related to the use of transfer equipment with generators that are separately derived systems.
Section 250.32(C) Ungrounded Systems (Revision)
Section 250.32(C) has been revised and expanded to address buildings or structures supplied by feeders or branch circuits and those supplied by ungrounded separately derived systems. The section has also been revised into a list structure in accordance with the NEC Style Manual. List item (2) includes feeders from an ungrounded, separately derived system where no overcurrent protection is provided at the point the feeders receive their supply or for feeders that have no overcurrent protection at their point of supply but instead at the building disconnect. List item (2) includes two subdivisions (a) and (b) that address feeders from ungrounded separately derived systems that do not have overcurrent protection and feeders from ungrounded separately derived systems that are provided with overcurrent protection. The difference relates to sizing rules for either an equipment-grounding conductor or a supply-side bonding jumper.
Section 250.52(A)(3) Concrete-Encased Electrodes (Revision)
Section 250.52(A)(3) has been revised for clarity and restructured into a list format. Concrete-encased electrodes are still permitted to be installed in either a horizontal (the most common) or vertical orientation, as long as there is not less than 20 feet of concrete in direct contact with the earth. A new informational note has been added to advise users about vapor barriers and other insulators that defeat concrete-encased electrode effectiveness.
Section 250.121 Use of Equipment-Grounding Conductors (New)
A new Section 250.121, “Use of Equipment Grounding Conductors,” has been added to Part V of Article 250. This new rule prohibits equipment-grounding conductors from being used as grounding-electrode conductors. Previous editions of the NEC were silent about this type of installation that has been applied in the field. This revision clarifies that this type of installation and practice is not acceptable.
Section 250.190 Conductor Shielding as Equipment-Grounding Conductor (Revision)
This revision expands this rule to include requirements for equipment-grounding conductor use, sizing and connections. Connections to and minimum sizing of grounding-electrode conductors are clarified in new subdivision (B). The changes in subdivision (C) provide users with information that clarifies when shielding on cables can serve as the required equipment-grounding conductor for the circuit. Where the shield of cables is insufficient to serve as the equipment-grounding conductor, a separate equipment-grounding conductor must be installed and sized using Table 250.122 based on the rating of the fuse size or the setting of the overcurrent-protective relay.
Section 250.191 Grounding System at AC Substations (New)
A new section, 250.191, and an associated informational note have been added to Part X of Article 250. Previous editions of the NEC did not effectively address grounding systems commonly installed and used in high-voltage AC substations. ANSI/IEEE 80-2000, IEEE Guide for Safety in AC Substation Grounding, goes into much more detail on how to design a proper grounding system for AC substations. It is important to recognize that many substations are not under the scope of the National Electrical Safety Code or a serving utility and that NEC rules are typically applicable. This revision is a good first step toward expanding the requirements for substation grounding-electrode systems and provides an appropriate reference to Part III of Article 250. A new informational note has been added to provide users with a reference to the appropriate IEEE guidelines for installing substation-grounding systems. This change reflects the continuing effort to include appropriate medium- and high-voltage requirements in the Code that apply to installations falling under the NEC scope.
The December issue of Electrical Contractor will feature Part III in this series on 2011 NEC changes. For more detailed information about these or any other important NEC changes, refer to the textbook “2011 NEC Significant Changes” published by the National Joint Apprenticeship and Training Committee. Additional detailed information about each proposal and comment resulting in NEC changes is provided in the NFPA Report on Proposals and Report on Comments for the 2011 NEC.
JOHNSTON is NECA’s executive director of standards and safety. He is former director of education, codes and standards for IAEI; a member of the IBEW; and an active member of the NFPA Electrical Section, Education Section and the UL Electrical Council. Reach him at firstname.lastname@example.org.