Editor's note: In this month's article, Mike Holt covers the new rule concerning neutral conductors in lighting circuits and some new requirements for tamper-resistant and AFCI receptacles.

314.28(E) Power Distribution Block in Junction Box

New provisions for power distribution blocks in pull and junction boxes have been added.

314.28 Boxes and Conduit Bodies for Conductors 4 AWG and Larger.

(E) Power Distribution Block. Power distribution blocks installed in junction boxes over 100 cu in. must comply with the following (Fig. 15):

  1. Installation. Be listed as a power distribution block.

  2. Size. Be installed in a box not smaller than required by the installation instructions of the power distribution block.

  3. Wire-Bending Space. The junction box is sized so that the wire-bending space requirements of 312.6 can be met.

  4. Live Parts. Exposed live parts on the power distribution block aren't present when the junction box cover is removed.

  5. Through Conductors. Where the junction box has conductors that don't terminate on the power distribution block(s), the through conductors must be arranged so the power distribution block terminals are unobstructed following installation.

Analysis: Power distribution blocks have a history of being used in large pull and junction boxes despite the fact that the Code has been silent on these installations. The only requirements for power distribution blocks were found in Art. 376, which applies only to metal wireways. This left uncertainty regarding the installation requirements for these blocks in boxes. The NEC now addresses this practice and provides clear, concise rules.

Only boxes exceeding 100 cu. in. can contain these blocks, and they must be listed. The values in Table 312.6 can be used for bending space at the terminals, and live parts must be covered just as required for wireways.

404.2(C) Switches Controlling Lighting

A new rule will require a neutral conductor at nearly every switch point.

404.2 Switch Connections.

(C) Switches Controlling Lighting. Switches controlling line-to-neutral lighting loads must have a neutral provided at the switch location.

Ex.: The neutral conductor isn't required at the switch location if:

  1. The conductors for switches enter the device box through a raceway that has sufficient cross-sectional area to accommodate a neutral conductor. (Fig. 16)

  2. Cable assemblies for switches enter the box through a framing cavity that's open at the top or bottom on the same floor level or through a wall, floor, or ceiling that's unfinished on one side.

Note: The purpose of the neutral conductor is to complete a circuit path for electronic lighting control devices.

Analysis: Many lighting control devices (such as occupancy sensors) require that the switch be provided with standby voltage and current at the switch in order to operate. Many electricians don't include a neutral conductor at switch locations, and the unfortunate result is the equipment grounding conductor being used as the neutral conductor. While the current on the equipment grounding conductor is typically less than 0.50mA, the accumulation of many switches in a building can result in an unacceptable amount of current on the equipment grounding conductors. With this change, gone are the days of using dead-end 3-way switches and two conductor switch loops.

The two exceptions address switch locations that use raceways and those that are at or near unfinished/accessible areas. The use of a raceway obviously allows the installer to pull in a neutral conductor should the need arise (provided the raceway is of adequate size), and the other exception allows for changing the wiring of the switch without resorting to removing drywall and other finish materials.

An Informational Note emphasizes the fact that this provision is for adding a dimmer switch. It's a bit surprising to see this Informational Note, due to the fact that statements of intent are typically not allowed in the Code.

406.4(D) Receptacle Replacements

A new requirement addresses the replacement of receptacles in areas requiring AFCI protection, tamper-resistant receptacles, or weather-resistant receptacles.

406.4 General Installation Requirements.

(D) Receptacle Replacement.

(4) Arc-Fault Circuit Interrupters. Effective Jan. 1, 2014, where a receptacle outlet is supplied by a branch circuit that requires arc-fault circuit-interrupter protection [210.12(A)], a replacement receptacle at this outlet must be one of the following.

  1. A listed (receptacle) outlet branch-circuit type arc-fault circuit-interrupter receptacle.

  2. A receptacle protected by a listed (receptacle) outlet branch-circuit type arc-fault circuit-interrupter type receptacle.

  3. A receptacle protected by a listed combination type arc-fault circuit interrupter type circuit breaker.

  4. Tamper-Resistant Receptacles. Listed tamper-resistant receptacles must be provided where replacements are made at receptacle outlets that are required to be tamper-resistant elsewhere in this Code.

  5. Weather-Resistant Receptacles. Weather-resistant receptacles must be provided where replacements are made at receptacle outlets that are required to be so protected elsewhere in the Code.

Analysis: As aging wiring systems become more of a concern in the electrical industry, the Code is taking a proactive approach to providing protection of these systems. Many areas of a dwelling require the use of AFCI protection in an effort to help avoid electrical fires. When AFCIs were first introduced into the NEC, the substantiation for their inclusion was based largely on electrical fires in older homes. With the inception of these devices, the Code began protecting new and future wiring systems but didn't address the older ones that contained many of the fires discussed in the AFCI arguments. This change expands the AFCI requirements to older homes. Because these older homes often don't contain an equipment grounding conductor, installation of an AFCI circuit breaker does very little in the way of protecting the branch circuits. The receptacle-type AFCIs also provide a significantly lower level of protection, but they will be required, nonetheless.

This requirement has an effective date of Jan. 1, 2014.

The 2008 NEC introduced the concept of tamper-resistant receptacles in dwelling units. The requirements of that section (406.11, now 406.12) apply to new installations. It could have been argued that one could install tamper-resistant receptacles in the locations required by 406.11, then remove them and replace them with traditional receptacles. While most people will agree that this argument is a huge stretch of the imagination, this change eliminates the issue before it arises. It also requires that, on existing dwelling units, any receptacles that are replaced will need to be replaced using tamper-resistant receptacles.

A similar change was made for weather-resistant receptacles, using the same logic as tamper-resistant receptacles.

406.12 Tamper-resistant Receptacles in Dwelling Units

The required locations for tamper-resistant receptacles in dwellings have been lessened, and a clarification has been made.

406.12 Tamper-Resistant Receptacles in Dwelling Units. All nonlocking type 15A and 20A, 125V receptacles in the following areas of a dwelling unit [210.52] must be listed as tamper-resistant.

  • Wall Space — 210.52(A)
  • Small-Appliance Circuit — 210.52(B)
  • Countertop Space — 210.52(C)
  • Bathroom Area — 210.52(D)
  • Outdoors — 210.52(E)
  • Laundry Area — 210.52(F)
  • Garage and Outbuildings — 210.52(G)
  • Hallways — 210.52(H)

Ex.: Receptacles in the following locations aren't required to be tamper-resistant:

  1. Receptacles located more than 5½ ft above the floor.

  2. Receptacles that are part of a luminaire or appliance.

  3. A receptacle located within dedicated space for an appliance that in normal use isn't easily moved from one place to another.

  4. Nongrounding receptacles used for replacements as permitted in 406.4(D)(2)(a).

Analysis: Receptacles installed above 5½ ft obviously don't pose the same risk to small children as those below that elevation. Likewise, receptacles that are rendered inaccessible by equipment, and those that are part of luminaires don't pose the same risk. The Code has recognized these facts and included an exception for them in this edition of the NEC.

An allowance has also been made to address the replacement of nongrounding receptacles because currently there are no nongrounding tamper-resistant receptacles.

Additionally, the term “nonlocking” was added to describe the types of receptacles to which this rule is intended to apply. Only those receptacles that are of the straight blade configuration will be required to comply with this section.

406.13 Tamper-resistant Receptacles in Guest Rooms and Guest Suites

A new requirement for tamper-resistant receptacles in guest rooms and guest suites was added.

406.13 Tamper-Resistant Receptacles in Guest Rooms and Guest Suites. Nonlocking-type 15A and 20A, 125V receptacles in guest rooms and guest suites must be listed as tamper-resistant.

Analysis: Guest rooms and guest suites often have children staying in them, so tamper-resistant receptacles have been added as a requirement for these locations. Guest suites that provide complete facilities for living, sleeping, cooking and sanitation are considered to be dwelling units by the NEC, and as such were already required to provide tamper-resistant receptacles. This change will now require tamper-resistant receptacles in all guest rooms and guest suites.

406.14 Tamper-resistant Receptacles in Child Care Facilities

A new requirement for tamper-resistant receptacles in “child care facilities” was added.

406.14 Tamper-Resistant Receptacles in Child Care Facilities. Nonlocking-type 15A and 20A, 125V receptacles in child care facilities must be listed as tamper-resistant.

Analysis: The definition for “child care facilities” in 406.2 deals with children of 7 yr of age and younger. Many of these younger children spend a great deal of time in child care facilities as well as in homes, yet the 2008 NEC only required tamper-resistant receptacles in dwelling units. Proponents of these devices immediately began hoping for expansion of these receptacles to other areas that are full of children. With this change, areas such as schools and day care facilities will be forced to use them. Other areas that aren't quite as clear, however, include hospitals and other medical centers.