This article is the third in the series of proposed changes for the 2011 National Electrical Code (NEC). The May and July issues of ELECTRICAL CONTRACTOR covered some of the proposed changes through Article 300. This article examines revisions between Articles 300 through 450 (covered in Chapters 3 and 4 of the Code).

The revisions result from the actions of the NEC technical committees at the report on proposals meeting in January 2009. There were more than 5,000 proposals submitted this cycle; more than 1,000 proposals were acted on favorably by the Code-Making Panels. The closing date for submitting public comments for any of the 2011 NEC change proposals is Oct. 23, 2009. Changes covered in this article can be modified based on public comments to the proposals or actions at the 2010 NFPA Annual Conference and Exposition.

Article 300 Wiring Methods and Materials

Section 300.4(E) Cables, Raceways, or Boxes Installed in or Under Roof Decking

Proposals 3-34, 3-39 Log Nos. 2763, 4608

(Revision) This requirement has been revised to clarify the minimum clear distance between cables and raceways from the lowest surface of corrugated roof decking material. The revision clarifies that the lowest surface is the measuring point. The other revisions to this section are the inclusions of boxes in the clearance requirement and a restriction from installing wiring methods concealed within the decking material. These wiring methods and materials are all vulnerable to penetration by roofing material fasteners. Maintaining the minimum clearances from the lowest underside surface of the decking material reduces likelihood of damage from roofing installation or replacement operations.

Section 300.11(A)(2) Non-Fire-Rated Assemblies

Proposal 3-73 Log No. 486

(Revision) Support wires and associated fittings for installing electrical wiring methods must provide secure support and have to be installed in addition to the ceiling-grid support wires. Where independent support wires are used, they have to be secured at both ends of the wire. The revision in this section provides a requirement for independent support wires for wiring methods in non-fire-rated suspended ceilings to be identified distinguishable by color, tagging or other effective means. This change results in improved enforceability and consistency with the same requirement for support wire identification that currently applies to independent support wires installed in fire-rated suspended ceiling assemblies.

Section 300.22(C)(2) Cable Tray in Other Spaces Used for Environmental Air (Plenums)

Proposal 3-97 Log No. 2298

(Revision) This new section recognizes the use of metallic cable tray systems in other spaces used for environmental air (plenums). A companion proposal removes the restriction of cable trays for use in 300.22 applications from Section 392.4 that existed in previous NEC editions. It is recognized that cables suitable for installation in other spaces that are used for environmental air handling should be permitted to be supported by metallic cable tray systems. These revisions clarify the permitted use and limitations.

Section 310.10(E) Shielding and Exception No. 2*

Proposals 6-21a, 6-21b, 6-23 Log Nos. CP 600, CP 601, 3868

(Revision) This section has been revised to remove the text describing the purpose of cable shielding from the Code text and incorporate it into a fine print note (FPN), because it is informational and not a requirement. The new FPN clarifies the purpose and the benefits of shielding in medium-voltage cables. This section has also been revised by inserting the words “equipment grounding conductors,” which clarifies that cable shields can be connected to equipment-grounding conductors in addition to grounding electrodes, grounding-electrode conductors and grounding busbars. A new Exception No. 2 has been added to permit listed nonshielded insulated conductors for use up to 5,000 volts for replacing existing nonshielded conductors in industrial establishments only under restrictive conditions as follows:

1. Where the condition of maintenance and supervision ensures that only qualified personnel install and service the installation

2. Conductors shall have insulation resistant to electric discharge and surface tracking, or the insulated conductor(s) shall be covered with a material resistant to ozone, electric discharge and surface tracking.

3. Where used in wet locations, the insulated conductor(s) shall have an overall nonmetallic jacket or a continuous metallic sheath.

4. Insulation and jacket thicknesses shall be in accordance with Table 310.13(D).

* Note: Article 310 has been renumbered and reorganized in the 2011 edition.

Article 399 Outdoor, Overhead Conductors, Over 600 Volts

Proposal 7-162 Proposal 680 Log No. 680

(New) This new article provides the requirements for overhead conductors outside that are installed for systems operating at over 600 volts. Many overhead electrical infrastructures are customer-owned and are outside of the control of serving utility companies. The NEC has been expanded to provide new rules that apply to overhead conductor installations. This proposal is the work of a specific task group assigned by the NEC Technical Correlating Committee to strengthen the NEC where it is lacking in rules applicable to medium- and high-voltage installations that are not under the exclusive control of the utility. Other requirements have been incorporated into various articles where the task group determined specific needs.

Section 342.30(C) Unsupported

Proposal 8-24a Log No. 2200 (includes various other similar revisions)

(Deleted exception) This revision deletes Subdivision (C), addressing unsupported raceways in lengths of 18 inches and shorter. This revision restores the practical application of support and securing requirements for conduit and tubing that was lost in the 2008 cycle when the 18-inch distance was specifically included. The 3-foot distance included in the rule provides the necessary parameters for installers and enforcement to apply when needed for achieving effective support and securing of conduit and tubing raceways. In addition to this revision for IMC, this change also occurs in other common numbering sections .30(C) for articles covering electrical metallic tubing, Type EMT; rigid metal conduit, Type RMC; rigid polyvinyl chloride conduit, Type PVC; and reinforced thermosetting resin conduit, Type RTRC.

Chapter 4 Equipment for General Use

Section 404.2(C) Switches Controlling Lighting Loads

Proposal 9-95 Log No. 1160

(New requirement) This new section provides a requirement to install a neutral (grounded) conductor at all switch boxes installed for lighting control use. An exception relaxes this requirement where the switch box is either supplied by a raceway or cable assembly where the cable assembly enters the box through a framing cavity that is open at the top or bottom on the same floor level, or through a wall, floor or ceiling that is unfinished on one side. The new requirement results from concerns about lighting control devices that require small amounts of current to operate, such as occupancy sensors. The current should not be permitted to be connected to the equipment--grounding conductor of the circuit. The revision appears to result in changes needed for product safety standards for listed lighting control devices.

Section 406.3(D) Replacements

Proposals 18-24, 18-30, 18-33 Log Nos. 3467, 3561, 3847

(Revision) The changes to this section address receptacle replacements in three new list items. New list item (4) requires that where receptacle replacements are made at receptacle outlets that are required to be so protected, arc-fault circuit interrupter-protected receptacles must be provided. New list item (5) requires that where receptacle replacements are made at outlets required to provide tamper-resistant receptacles, the replacement shall be a tamper-resistant type. New list item (6) requires that where receptacle replacements are made at outlets that require weather-resistant receptacles, weather-resistant receptacles must be installed. The revision results in new requirements for receptacle manufacturers.

Section 406.12 Tamper-Resistant Receptacles for Dwelling Units, 406.13 Tamper-Resistant Receptacles in Guest Rooms and Guest Suites, and 406.14 Tamper-Resistant Receptacles in Child Care Facilities

Proposals 18-62, 18-68, 18-71, 18-82, 18-87 Log Nos. 727, 2786, 3848, 728, 1167

(Revisions, new sections and new exceptions) The requirements for tamper-resistant receptacles have been expanded beyond dwelling units. New exceptions have been added to relax the requirement for height, for when the receptacle is part of a listed assembly, or for when the receptacle is installed in a dedicated space for appliances. Former Section 406.11 has been expanded into three sections that address different locations where tamper-resistant receptacles are now required. The word nonlocking has been added to this requirement to clarify the receptacle types covered by the rule. A new 406.13 has been added that requires tamper-resistant receptacles in all guest rooms and guest suites of hotels and motels and a new Section 406.14 requires tamper--resistant receptacles in child care facilities. These revisions provide enhanced protection for unsuspecting children in occupancies other than just dwellings where children and the concerns are present.

Article 410 Luminaires, Lampholders, and Lamps

Light-Emitting Diode—LED Technologies

(Revision) Changes accepted throughout Article 410 result in rules regarding light-emitting diode (LED) technologies being addressed in the NEC. This technology has evolved to the stage where luminaires and lighting systems are being manufactured using LEDs driven by electronic power supplies.

Section 408.3(F)(2) Ungrounded Systems

Proposal 9-140 Log No. 2764

(New) This revision incorporates a new requirement to field-mark switchboards and panelboards that are supplied by ungrounded systems (sources). The new rule includes specific language that must be used on the labels that warn users of the ungrounded system and what the operating voltage is. The label has to include the following wording:

“Caution Ungrounded System Operating _____ Volts Between Conductors”.

Section 408.4 Field Identification Required

Proposal 9-142 Log No. 1494

(Revision) This section has been revised by adding a new subdivision (B) that requires each switchboard or panelboard to be field-marked as to where the power supplying the equipment originates. The title of this section has also been changed from “Signage” to “Field Identification Required.” This revision results in increased safety for workers by enhancing the ability to readily identify power sources supplying equipment for maintenance or other reasons that require workers to establish electrically safe work conditions. This new marking requirement does not in any way relive the requirements of NFPA 70E 2009, Standard for Electrical Safety in the Workplace.

Section 440.9 Equipment Grounding

Proposal 11-129 Log No. 2053

(New) This new section adds a requirement for installing a wire-type equipment-grounding conductor with any wiring method used to supply air conditioning and refrigeration equipment. The new text does not clearly indicate whether the requirement applies to the branch circuit only or both the feeder and branch circuit levels of the system. As it is currently worded, the rule would have to apply to both feeders and branch circuits that supply this type of equipment. The substantiation indicates problems with the conduit and tubing types of equipment-grounding conductors that result in ineffective ground-fault current paths when couplings become loose or separate some time after installation. It should be noted that wiring methods should be properly secured and supported in compliance with the NEC and should also not be subject to physical damage or otherwise be suitable for the location. The change results in having to install a wire-type equipment-grounding conductor in all wiring methods supplying air conditioning equipment, even if the conduit, tubing or cable assembly is a suitable equipment-grounding conductor in accordance with 250.118.

Section 450.14 Disconnecting Means

Proposal 9-176 Log No. 3821

(New) This new section in Article 450 provides a requirement for installing a disconnecting means in the primary supply of a transformer, and it must generally be located in sight from the transformer. The new rule also includes an option for locating the disconnecting means out of sight from the transformer, but it has to be capable of being locked in the open position. The disconnecting means requirement does not apply to listed Class 2 or Class 3 transformers. This change does not impact current requirements for transformer overcurrent protection as provided in 450.3 and protecting the conductors supplied by the transformer as provided in 240.21.


The revisions in this article include some, but not all, significant changes proposed to the 2011 NEC. The revisions resulted from the actions of the NEC technical committees at the report on proposals meeting in January 2009. These revisions could be affected by public comments to the proposals. The closing date for submitting public comments for any of the 2011 NEC change proposals is Oct. 23, 2009. Forms for submitting comments are available at Part 4 of the series on proposed changes will cover significant changes in Chapters 5 and 6 of the Code.

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