Know What’s New

In this latest code cycle, the Code Making Panels (CMPs) sifted through 3,688 change proposals. Some of the resulting changes were minor editorial revisions. Others were more significant, such as new Articles, Sections, Exceptions, and Fine Print Notes.

Why does the NEC undergo revision every three years? After all, electricity doesn’t change every three years. For one thing, the NEC must keep up with changes in methods and materials as technology marches forward. Other factors behind those 3,688 proposals include fire data and efforts to make the NEC more user-friendly.

Code Change Wrap-up

We’ve highlighted what we consider to be the top 10 code changes for the industry in general, but this cycle produced hundreds of changes. Which ones really apply to the work you do? Use this simple three-step process to find the answer:

  1. Review a sampling of typical jobs you did over the past year.
  2. Note which NEC requirements apply.
  3. Look up those requirements in the 2008 NEC. Compare them to the 2005 requirements.

As you do this, jot down some notes on what you think should be different in the NEC. This will give you the basis for making change proposals of your own for the 2011 NEC. You have about a year left to submit those. But that time will be gone before you know it, so get started now.

Top 10 2008 NEC Change Rules

1. 210.4 Multiwire Branch Circuits
The rule for “Simultaneous Disconnecting Means” requirements for multiwire branch circuits was expanded.


Fig. 210-2

(B) Disconnecting Means. Each multiwire branch circuit shall have a means to simultaneously disconnect all ungrounded conductors at the point where the branch circuit originates. (See Figure 210.2)

Author’s Comment: Individual single-pole circuit breakers with handle ties identified for the purpose, or a breaker with a common internal trip, can be used for this application [240.15(B)(1)].

CAUTION: This rule is intended to prevent people from working on energized circuits they believe are disconnected.

Analysis: Multiwire branch circuits can offer unexpected shock hazards when work is being done on them unless all ungrounded conductors from the multiwire branch circuit are disconnected simultaneously. This revised section requires each ungrounded conductor of a multiwire branch circuit to be disconnected simultaneously by common trip 2-pole or 3-pole circuit breakers or single-pole circuit breakers with an identified handle tie.

2. 210.8 Ground-Fault Circuit-Interrupter Protection for Personnel (GFCI)
Outdoor GFCI-protection requirements for 15A and 20A, 125V receptacles at nondwelling unit occupancies were revised.


Fig. 210-10

(B) Other Than Dwelling Units

(4) Outdoors - All 15A and 20A, 125V receptacles installed outdoors shall be GFCI protected. (See Figure 210–10)

Analysis: The 2005 NEC only required 15A and 20A, 125V “outdoors in public spaces—for the purpose of this section a public space is defined as any space that is for use by, or is accessible to, the public” to have GFCI protection. This change now requires GFCI protection for these types of receptacles installed at all outdoor locations, except as provided by the exceptions for snow-melting and deicing equipment and industrial establishments.

3. 250.4 General Requirements for Grounding and Bonding
A new Fine Print Note alerts Code users to the advantage of reducing the length of the grounding electrode conductor.


Fig. 250-4

(A) Grounded Systems

(1) Electrical System Grounding. Electrical power systems, such as the secondary winding of a transformer are grounded to the earth to limit the voltage caused by lightning, line surges or unintentional contact by higher-voltage lines.

FPN: An important consideration for limiting the imposed voltage is the routing of bonding and grounding conductors so that they are not any longer than necessary to complete the connection without disturbing the permanent parts of the installation and so that unnecessary bends and loops are avoided. (See Figure 250-4)

Author’s Comment: System grounding helps reduce fires in buildings as well as voltage stress on electrical insulation, thereby ensuring longer insulation life for motors, transformers, and other system components.

Analysis: This new Fine Print Note is intended to call attention to the instructions contained in Sections 800.100(A)(5), 810.21(E), and 820.100(A)(5) that grounding conductors be run as short as possible and as straight as possible. This provides an effective path to the earth for line surges caused by lightning events.

4. 250.32 Buildings or Structures Supplied by Feeder or Branch Circuit
The rule that permitted the regrounding of the neutral conductor at separate buildings and structures was deleted.


Fig. 250-21

Fig. 250-22

(B) Equipment Grounding Conductor. To quickly clear a ground fault and remove dangerous voltage from metal parts, the building or structure disconnecting means shall be connected to the circuit equipment grounding conductor of a type described in 250.118. Where the supply circuit equipment grounding conductor is of the wire type, it shall be sized to 250.122, based on the rating of the supply circuit overcurrent device rating. (See Figure 250-21)

Exception: For existing premises, when an equipment grounding conductor was not run to the building or structure disconnecting means, the building or structure disconnecting means can remain connected to the neutral conductor where there are no continuous metallic paths between buildings and structures, ground-fault protection of equipment isn’t installed on the supply side of the circuit, and the neutral conductor is sized no smaller than the larger of:

(1) The maximum unbalanced neutral load in accordance with 220.61.

(2) The rating of the circuit overcurrent device, in accordance with 250.122.

Caution: To prevent dangerous objectionable neutral current from flowing onto metal parts [250.6(A)], the supply circuit neutral conductor is not permitted to be connected to the remote building or structure disconnecting means [250.142(B)]. (See Figure 250–22)

Analysis: In the 2005 NEC, 250.32(B)(2) permitted the neutral conductor to serve as the effective ground-fault current path, this rule was converted into an exception for existing premises. Using the neutral conductor to connect metal objects to the effective ground-fault current path is a dangerous practice, especially if the neutral becomes open.

5. Article 708 – Critical Operations Power Systems
A new article addressing Critical Operations Power Systems was added to the 2008 NEC.

The provisions of this article apply to the installation, operation, monitoring, control, and maintenance of premises wiring intended to supply, distribute, and control electricity to designated critical operations areas in the event of disruption to elements of the normal system.

Critical operations power systems are those systems so classed by municipal, state, federal, or other codes, by any governmental agency having jurisdiction, or by facility engineering documentation establishing the necessity for such a system. These systems include but are not limited to power systems, HVAC, fire alarms, security, communications, and signaling for designated critical operations areas.

Critical Operations Power Systems are generally installed in vital infrastructure facilities that, if destroyed or incapacitated, will disrupt national security, the economy, public health or safety; and where enhanced electrical infrastructure for continuity of operation is deemed necessary by governmental authority.

Threats to facilities that may require transfer of operation to the critical systems include both naturally occurring hazards and human-caused events.

Analysis: Recent terrorist events and natural disasters, such the World Trade Center attack and Hurricane Katrina, highlighted the need to assess the adequacy of the National Electrical Code requirements for electrical infrastructure protection and reliability. This new Article 708 was created by a task group developed in response to Homeland Security activity, specifically how to keep an emergency system operating for days. The task group was formed to review requirements in the NEC and other NFPA codes and standards covering emergency and standby power systems and sources, and signaling systems.

6. 250.94 Intersystem Bonding Terminal
A new rule requires an intersystem bonding terminal for communications systems.


Fig. 250-39

An external accessible intersystem bonding terminal for the grounding and bonding of communications systems shall be provided at service equipment and disconnecting means for buildings or structures supplied by a feeder. (See Figure 250– 39)

The intersystem bonding terminal shall not interfere with the opening of any equipment enclosure and be one of the following:

  1. Terminals listed for grounding and bonding attached to a meter socket enclosure.
  2. Bonding bar connected to the equipment grounding conductor with a minimum 6 AWG copper conductor.
  3. Bonding bar connected to the grounding electrode conductor with a minimum 6 AWG copper conductor.

Author’s Comment: According to Article 100, an intersystem bonding terminal is a device that provides a means to connect communications systems grounding and bonding conductors to the building grounding electrode system. See (See Figure 250-39)

Exception: At existing buildings or structures, an external accessible means for bonding communications systems together can be:

  1. Nonflexible metallic raceway,
  2. Grounding electrode conductor, or
  3. Connection approved by the authority having jurisdiction.

FPN No. 2: Communications systems shall be bonded to the intersystem bonding terminal in accordance with the following:

  1. Antennas/Satellite Dishes, 810.15 and 810.21
  2. CATV, 820.100
  3. Telephone Circuits, 800.100

Author’s Comment: All external communications systems must be bonded to the intersystem bonding terminal to minimize the damage to communications systems from induced potential (voltage) differences between the systems from a lightning event.

Analysis: This is one of several correlated proposals to improve the requirements related to the intersystem bonding and grounding of communications systems. This provides a more accessible, safer means of bonding all systems, such as power and communications, together.

7. 250.52 Grounding Electrodes
The requirements for a concrete-encased electrode now include vertical electrodes as well as what to do when multiple isolated concrete-encased electrodes are present.


Fig. 250-26

Fig. 250-27

(A) Electrodes Permitted for Grounding.

(3) Concrete-Encased Grounding Electrode. A concrete-encased electrode is an electrode that is encased by at least 2 in. of concrete, located horizontally near the bottom or vertically within a concrete foundation or footing that is in direct contact with the earth consisting of one of the following: (See Figure 250–26)

  1. Twenty feet of one or more bare or zinc galvanized or other electrically conductive coated steel reinforcing bars bonded together by the usual steel tie wires not less than ½ in. in diameter, or
  2. Twenty feet of bare copper conductor not smaller than 4 AWG

Author’s Comment: If a moisture/vapor barrier is installed under a concrete footer, then the steel rebar is not considered a concrete-encased electrode.

Where multiple concrete-encased electrodes are present at a building or structure, only one is required to serve as the grounding electrode system. (See Figure 250–27)

Author’s Comments:

  • The grounding electrode conductor to a concrete-encased grounding electrode isn’t required to be larger than 4 AWG copper [250.66(B)].
  • The concrete-encased grounding electrode is also called an “Ufer Ground,” named after Herb Ufer, the person who determined its usefulness as a grounding electrode in the 1960s. This type of grounding electrode generally offers the lowest ground resistance for the cost.

Analysis: The requirements for concrete-encased electrodes have been expanded to allow structural steel rebar in vertical foundations to be suitable as a grounding electrode, as long as it meets all of the requirements for horizontal structural steel rebar electrodes. In addition, the 2008 NEC clarified that in a building or structure where multiple isolated concreteencased electrodes are present, such as for spot footings, only one of these “present” electrodes will be required to be used. The purpose of the NEC [90.1] is the “practical safeguarding of persons and property,” and requiring all of the concrete-encased electrodes to be bonded together served no safeguarding purpose.

8. 406.8 Receptacles in Damp or Wet Locations
Receptacles installed in wet locations are now required to be weather resistant.


Fig. 406-4

(B) Receptacles in Wet Locations.

(1) 15A and 20A Receptacles. All 15A and 20A receptacles installed in a wet location shall be within an enclosure that is weatherproof when an attachment plug is inserted and all nonlocking 15A and 20A, 125V and 250V receptacles in a wet location shall be listed as weather resistant. (See Figure 406–4)

Exception: Receptacles subject to routine high-pressure washing spray may have an enclosure that is weatherproof when the attachment plug is removed.

Author’s Comments:

  • Wet locations are those subject to saturation with water, and unprotected locations exposed to weather [Article 100].
  • Exposed plastic surface material of weather-resistant receptacles must have UV resistance to ensure deterioration from sunlight does not take place or is minimal. In testing, receptacles are subjected to temperature cycling from very cold to very warm conditions and then additional dielectric testing. The rapid transition from the cold to warm temperature will change the relative humidity and moisture content on the device and the dielectric test ensures that this will not present a breakdown of the insulation properties.

Analysis: The change to this subsection was made in response to concerns that receptacles located outdoors are not always protected from detrimental conditions such as low temperatures, exposure to ultraviolet radiation (UV), physical damage, etc., and that weatherproof covers and enclosures do not always provide sufficient protection from the elements. The new exception allows receptacle covers in high-pressure spray washing areas to be of the type that is weatherproof when the attachment plug is removed. When a weatherproof while-in-use cover is used with high-pressure spray cleaning, liquid can spray into the enclosure through the cable openings. This change allows the use of a snap cover that does not have a cable opening in it while closed.

9. 406.11 Tamper-Resistant Receptacles in Dwelling Units
Requirements for tamper-resistant receptacles were added to the 2008 NEC.

In dwelling units, all 15A and 20A, 125V receptacles shall be listed as tamper resistant.

Author’s Comment: This rule applies to receptacles installed behind appliances, above countertops, and other locations out of the reach of children.

Analysis: This new section requires the use of listed tamper-resistant receptacles for all 15A and 20A, 125V receptacles installed in dwelling units.

10. 310.15 Ampacities for Conductors Rated 0–2,000 Volts
A new subsection adds ambient temperature adjustments for conduits installed on rooftops.

(B) Tables

(2) Adjustment Factors

(C) Raceways Exposed to Sunlight on Rooftops. The ambient temperature adjustment contained in Table 310.15(B)(2)(c) is added to the outdoor ambient temperature for conductors or cables that are installed in raceways exposed to direct sunlight on or above rooftops when applying ampacity adjustment correction factors contained in Table 310.16.

FPN No. 1: See ASHRAE Handbook–Fundamentals (www.ashrae.org) for the average ambient temperatures in various locations.


Fig. 310–5

FPN No. 2: The temperature adders in Table 310.15(B)(2)(c) are based on the results of averaging the ambient temperatures.

Analysis: This new subsection requires the ambient temperature used for ampacity correction to be adjusted where conductors or cables are installed in conduit on or above a rooftop and the conduit is exposed to direct sunlight. The reasoning behind this change is that the air inside conduits in direct sunlight is significantly hotter than the surrounding air, and appropriate ampacity corrections must be made in order to comply with 310.10.

For example, a conduit with three 6 THHN conductors with direct sunlight exposure that is 3/4 in. above the roof will require 40°F to be added to the correction factors at the bottom of Table 310.16. Assuming an ambient temperature of 105°F, the temperature to use for conductor correction will be 145°F (105°F + 40°F), the 6 THHN conductor ampacity after correction will be 43.50A (75A x 0.58). (See Figure 310–5)

Author’s Comment: When adjusting conductor ampacity, use the conductor ampacity as listed in Table 310.16 based on the conductor’s insulation rating. In this case, it’s 75A at 90°F. Conductor ampacity adjustment is not based on the temperature terminal rating as per 110.14(C).