introduction by EC&M staff
It's no secret that many electrical professionals have a love/hate relationship with the National Electrical Code (NEC). The good news is it's revised on a three-year cycle. The bad news is that three years pass all too quickly. Just when you think you've got a firm grip on the last set of revisions, a new comprehensive set of changes comes rolling at you. One would think that a document that's been around since the late 1890s would only require minor tweaks and revisions. However, the steady introduction of new products and technologies into the marketplace — coupled with the release of new research findings by various public and private groups — creates a seemingly never-ending flow of necessary revisions (some of which are comprehensive) to this widely accepted electrical code.
In our continued efforts to serve your Code needs, we've enlisted the help of our trusty NEC Consultant Mike Holt to shed light on the key changes in this new edition of the Code. Once again, he's delivered in a big way, covering everything from new GFCI and AFCI requirements to more grounding and bonding rules to conductor ampacity guidelines. All 25 changes highlighted in this article are supported by an analysis section, where Holt offers keen insight into why the change was brought about and how it might affect you on future projects. Although we've highlighted what we consider to be the most influential changes, it's important to realize that this cycle produced a multitude of revisions.
So find a quiet place, dive into this article, and take all the time you need to absorb some of the most significant new articles, sections, exceptions, and fine print notes in the 2011 NEC. When you're finished, you'll undoubtedly feel one step ahead of the game.
110.24 Available Fault Current
A new section requires some equipment to be marked with the available fault current and requires updating of that marking if modifications of the electrical system occur.
110.24 Available Fault Current.
(A) Field Marking. Service equipment in other than dwelling units must be legibly field-marked with the maximum available fault current, including the date the fault current calculation was performed and be of sufficient durability to withstand the environment involved. (Fig. 1)
(B) Modifications. When modifications to the electrical installation affect the maximum available fault current at the service, the maximum available fault current must be recalculated to ensure the service equipment ratings are sufficient for the maximum available fault current at the line terminals of the equipment. The required field marking(s) in 110.24(A) must be adjusted to reflect the new level of maximum available fault current.
Exception: Field markings aren't required for industrial installations where conditions of maintenance and supervision ensure that only qualified persons service the equipment.
Analysis: All equipment must have an interrupting rating or short circuit current rating that's equal to or greater than the available fault current [110.9 and 110.10]. As premises wiring systems age, utilities may change transformers in an effort to become more efficient or to increase capacity. When this occurs, the available fault current increases, many times resulting in noncompliant (and dangerous) wiring systems. This NEC change is intended to alert Code users to the fact that when utilities change transformers — or when emergency or standby systems are installed — the ratings of equipment must be re-evaluated.
Opponents of this NEC change argue that oftentimes the ratings of equipment are based on a “worst-case” scenario. While this is suitable for designing a system, it isn't suitable for performing the calculations required to establish the proper personal protective equipment (PPE) necessary to work on the equipment. When artificially high values of fault current are used for equipment ratings, a lower PPE rating is often the result of the calculations.
210.8 GFCI Protection
There were several changes made to this section of the Code, addressing accessibility and location issues.
A new requirement addresses the accessibility of the test and reset functions of GFCI devices.
210.8 GFCI Protection. Ground-fault circuit interruption for personnel must be provided as required in 210.8(A) through (C). The Ground-fault circuit-interrupter device must be installed at a readily accessible location.
Analysis: The Code previously didn't address the accessibility of the test and reset functions of GFCI devices. This presents two problems: First, building owners are subjected to the inconvenience of using ladders (or less safe devices) to reach the reset button should a GFCI device trip. Secondly, the listing standards of GFCIs require that they be tested on a monthly basis. While it's true that many people don't test their GFCI devices, some who would perform such tests won't go through the extra effort of finding a ladder to access these devices if they aren't readily accessible.
This change will require GFCIs in obvious locations, such as bathrooms and dwelling unit garages, to have their test and reset buttons readily accessible, but it also applies to less obvious locations, such as receptacles on rooftops and in soffits for holiday lighting.
A revision to this next requirement increases the locations of GFCI-protected outlets in patient care areas of health care facilities.
210.8(B)(5) Sinks. All 15A and 20A, 125V receptacles installed within 6 ft of the outside edge of a sink must be GFCI-protected.
Ex. 1: In industrial laboratories, receptacles used to supply equipment where removal of power would introduce a greater hazard aren't required to be GFCI-protected.
Ex. 2: Receptacles located in patient bed locations of general care or critical care areas of health care facilities aren't required to be GFCI-protected.
Analysis: A change to the 2008 NEC required GFCI protection near all sinks in nondwelling occupancies. One of the concerns raised by this change was the need for life support equipment to be supplied by an outlet that isn't GFCI-protected. Due to this, an exception was written that exempted all receptacles in patient care areas (other than bathrooms). Although this certainly took care of the life support issue, it also removed GFCI protection from all other equipment that isn't life safety oriented. For example, the many sinks found in a dental office were exempt, despite the fact that the patient is often very vulnerable to electric shock due to the invasive nature of many dental procedures. This change more accurately expresses the concerns of the medical community, while adding protection to equipment that isn't essential to life support.
GFCI protection was added to indoor wet locations of nondwelling occupancies.
210.8(B)(6) Indoor wet locations. All 15A and 20A, 125V receptacles installed indoors in wet locations must be GFCI-protected.
Analysis: Many areas, such as car washes, food processing areas, and similar locations, share the same hazards as outdoor locations, yet GFCI protection has never been required in these locations. This change will now require that these areas receive the same protection against electric shock as required for outdoor locations. It's worth noting that this change was accepted without any documented incidents cited.
A new requirement for GFCI protection of 15A and 20A, 125V receptacles near showering facilities was added.
210.8(B)(7) Locker Rooms. All 15A and 20A, 125V receptacles installed in locker rooms with associated showering facilities must be GFCI-protected.
Analysis: Requirements for GFCI protection of receptacles in bathrooms have been in place for a very long time. In Art. 100, a bathroom is very clearly defined — and not all locker rooms fall under that definition. The hazards that exist in a bathroom are the same as those encountered in a locker room — and perhaps even more so. A typical locker room that has associated showering facilities will probably contain tiled floors that are wet, people with bare feet, and people using electrical appliances (razors, hair dryers, curling irons, etc.). Therefore, GFCI protection was added for all 15A and 20A, 125V receptacles located in these facilities.
A new requirement adds GFCI protection for receptacles located in nondwelling unit garages that don't fall under the scope of Article 511.
210.8(B)(8) Garages. All 15A and 20A, 125V receptacles installed in garages, service bays, and similar areas where electrical diagnostic equipment, electrical hand tools, or portable lighting equipment are to be used must be GFCI-protected. (Fig. 2)
Analysis: This change expands GFCI protection requirements to all commercial garages. Article 511 applies only to those garages “in which volatile flammable liquids or flammable gases are used for fuel or power.” A facility that repairs only diesel-powered vehicles doesn't fall under the requirements of Article 511, because diesel fuel is a combustible liquid, not a flammable liquid. Although the same electric shock hazards exist regardless of the fuel type employed, areas that use only diesel fuel didn't require GFCI protection in previous editions of the Code.
210.12 Arc-Fault Circuit-Interrupter Protection for Dwelling Units
Changes have been made to this section to address fire alarm circuiting, Type MC cables, concrete-encased raceways, and branch circuit extensions or modifications.
210.12(A) Where Required. All 15A or 20A, 120V branch circuits in dwelling units supplying outlets in family rooms, dining rooms, living rooms, parlors, libraries, dens, bedrooms, sunrooms, recreation rooms, closets, hallways, or similar rooms or areas must be protected by a listed AFCI device of the combination type. (Fig. 3 on page 28)
Ex. 1: AFCI protection can be of the branch circuit type located at the first outlet if the circuit conductors are installed in RMC, IMC, EMT, or Type MC or steel armored Type AC cable meeting the requirements of 250.118, and the AFCI device is contained in a metal outlet or junction box.
Ex. 2: Where a listed metal or nonmetallic conduit or tubing is encased in not less than 2 in. of concrete for the portion of the branch circuit between the branch circuit overcurrent device and the first outlet, an outlet branch circuit AFCI at the first outlet is permitted to provide protection for the remaining portion of the branch circuit.
Ex. 3: AFCI protection can be omitted for an individual branch circuit to a fire alarm system in accordance with 760.41(B) and 760.121(B), if the circuit conductors are installed in RMC, IMC, EMT, or steel sheath Type AC or MC cable that qualifies as an equipment grounding conductor in accordance with 250.118, with metal outlet and junction boxes.
(B) Branch-Circuit Extensions or Modifications — Dwelling Units. Where branch-circuit wiring is modified, replaced, or extended in any of the areas specified in 210.12(A), the branch circuit must be protected by:
(1) A listed combination AFCI located at the origin of the branch circuit; or
(2) A listed outlet branch circuit AFCI located at the first receptacle outlet of the existing branch circuit.
Analysis: Fire alarm systems covered by Art. 760 have been exempted from the requirements of AFCI protection, but the circuiting of those systems was previously not addressed. This inadvertently left a loophole for installers to incorporate other outlets in areas specified by 210.12 on the same circuit as the fire alarm system and omit the AFCI protection required for circuits in those areas. This change also includes MC cable as a permitted wiring method when employing this exception.
Section 210.12 Ex. 1 has been revised to allow MC cables as one of the allowable wiring methods in the exception. MC cable meeting the requirements of 250.118 has been proven safe, so this allowance seems fair enough.
New to the NEC is 210.12(A) Ex. 2. Concrete encased raceways obviously provide an increased level of protection for circuit conductors, so a new exception was added to allow such raceways to be installed without AFCI protection at the source, provided that there's an outlet type AFCI installed at the first outlet of the circuit.
Also new to the NEC is subsection (B), dealing with branch-circuit extensions or modifications in existing buildings. The question of what to do with existing buildings in regard to AFCI protection has been prevalent ever since AFCI requirements were added to the Code in 1999. With this change, it's clear that when branch circuit wiring is extended or modified, some level of AFCI protection will be required.
210.52 Dwelling Unit Receptacle Outlet Requirements
A change to the wall spacing requirements has been made to address fixed cabinets, and the wall spacing requirements have been clarified.
210.52(A)(2) Definition of Wall Space.
(1) Any space 2 ft or more in width, unbroken along the floor line by doorways and similar openings, fireplaces, and fixed cabinets.
(2) The space occupied by fixed panels in exterior walls.
(3) The space occupied by fixed room dividers, such as freestanding bar-type counters or guard rails.
(3) Floor Receptacle Outlets. Floor receptacle outlets aren't counted as the required receptacle wall outlet if they're located more than 18 in. from the wall.
(4) Countertop Receptacles. Receptacles installed for countertop surfaces as required by 210.52(C) can't be used to meet the receptacle requirements for wall space as required by 210.52(A). (Fig. 4)
Analysis: The substantiation for the change to (A)(2)(1) is to deal with kitchen cabinets. Obviously, the Code doesn't expect a receptacle installed in front of lower kitchen cabinets to satisfy the wall space receptacles of this section. While this makes sense — and seems to be a clarification that's worth making — it also brings with it technical changes as well. For example, built-in bookcases often consume entire walls in dwelling unit libraries, studies, offices, and similar rooms. With this change, it seems receptacles are no longer required in such bookcases.
Changes made to 210.52(A)(4) have been done to address a fairly odd situation. It's quite common for a kitchen peninsular or island countertop to create a “wall” between the kitchen and dining room (or other room). When this occurs, 210.52(A)(1) requires receptacles on the back of the peninsula or island in order to accommodate the dining area. In previous NEC editions, the required countertop receptacle could be used to satisfy this requirement, provided the receptacle wasn't higher than 5½ ft above the floor [210.52(4)]. This not only made for a Code-compliant installation, but also an invitation to have cords stretched across the dining room in order to reach the elevated receptacle. This change eliminates that loophole from the NEC and clearly states that the required countertop receptacles required by 210.52(C) are in addition to any receptacles required in other parts of 210.52(A).
A 15A or 20A, 125V receptacle is now required in dwelling unit accessory buildings.
210.52(G) Dwelling Unit Garage, Basement, and Accessory Building Receptacles.
(1) Not less than one 15A or 20A, 125V receptacle outlet, in addition to any provided for a specific piece of equipment, must be installed in each basement, in each attached garage, and each detached garage or accessory building with electric power.
Analysis: The NEC has long required a 15A or 20A, 125V receptacle for detached dwelling unit garages that are provided with electric power. This Code change recognizes the fact that many accessory buildings to dwellings aren't garages, but rather workshops, storage sheds, and similar buildings. Storage sheds are often used to house lawn and garden equipment, some of which require electricity for battery charging and other purposes. The NEC now requires a receptacle to be installed in these buildings whenever there's electric power installed in them (for lighting or similar purposes).
A new requirement to provide receptacles in foyers was added.
210.52(I) Foyer Receptacles. Foyers that aren't part of a hallway [210.52(H)] having an area greater than 60 sq ft must have a receptacle located on any wall space 3 ft or more in width and unbroken by doorways, floor to ceiling windows, and similar openings.
Analysis: Newer homes are often built with substantial foyers, some of which can be larger than other rooms of the house. In previous editions of the Code, these areas were typically treated as hallways, with only one receptacle being required and only one being installed. This change will now require foyers to have the same receptacle requirements as a bedroom, family room, dining room, or similar area. I guess the only question now is…what's a foyer?
250.2 Bonding Jumper, Supply-Side
A new term “supply-side bonding jumper” was added.
Bonding Jumper, Supply-Side. A conductor on the supply side or within a service or separately derived system to ensure the electrical conductivity between metal parts required to be electrically connected. (Fig. 5)
Analysis: Equipment bonding jumpers are used often in the NEC, although the manner in which they're sized depends on the location (in the circuit) of the bonding jumper. Generally speaking, bonding conductors located downstream of an overcurrent device are sized in accordance with 250.122, based on the rating of the overcurrent device. Bonding conductors upstream of an overcurrent device, such as the supply side of a service or between a transformer and panelboard, are typically sized using Table 250.66 and the 12½% rule discussed in 250.102(C). This Code change not only provides a new term to more accurately describe an existing conductor, but also should help clear up the sizing confusion that many people have with bonding conductors.
250.30 Grounding Separately Derived Systems
This section has been reorganized and includes many revisions and notes to clarify the grounding and bonding requirements of separately derived systems.
(A) Grounded Systems. Separately derived systems must be grounded and bonded in accordance with (A)(1) through (A)(8).
(3) System Neutral Conductor Size. If the system bonding jumper is installed at the disconnecting means instead of at the source, the following requirements apply:
(a) Sizing for Single Raceway. Because the neutral conductor of a derived system serves as the effective ground-fault current path for ground-fault current, it must be routed with the ungrounded conductors of the derived system and be sized not smaller than specified in Table 250.66, based on the area of the ungrounded conductor of the derived system. (Fig. 6)
(b) Parallel Conductors in Two or More Raceways. If the conductors from the derived system are installed in parallel in two or more raceways, the neutral conductor of the derived system in each raceway or cable must be sized not smaller than specified in Table 250.66, based on the area of the largest ungrounded conductor of the derived system in the raceway or cable. In no case is the neutral conductor of the derived system permitted to be smaller than 1/0 AWG [310.10(H)].
(6) Grounding Electrode Conductor, Multiple Separately Derived Systems.
(a) Common Grounding Electrode Conductor. The common grounding electrode conductor can be one of the following:
(1) A conductor not smaller than 3/0 AWG copper or 250kcmil aluminum.
(2) The metal frame of the building/structure that complies with 250.52(A)(2) or is connected to the grounding electrode system by a conductor not smaller than 3/0 AWG copper or 250kcmil aluminum.
(C) Outdoor Source. If the separately derived system is located outside the building/structure, a connection to the grounding electrode must be made at the separately derived system location.
Analysis: Considering the amount of changes that have occurred in this section, it wouldn't be entirely inaccurate to say that the whole section has been rewritten. Here are a couple of items worth noting.
Section 250.30(A)(3) mainly borrows the text that was previously in 250.30(A)(8). It does, however, add new text to provide guidance on sizing the grounded conductor for a delta (corner grounded) system. In these applications, the grounded conductor must be the same size as the ungrounded conductors.
In 250.30(A)(6), the grounding electrode conductor(s) for multiple separately derived systems has been changed to clarify that structural metal can be used to ground multiple separately derived systems, provided that the structural metal complies with 250.52(A)(2) or is connected to the grounding electrode system by a conductor not smaller than 3/0 AWG CU or 250kcmil AL.
Section 250.30(C) is new to the NEC. This subsection addresses separately derived systems that are installed outside of a building or other structure. When this is the case, a grounding electrode connection to the transformer must be provided.
250.52(A) Electrodes Permitted for Grounding
The rule explaining when a structural metal frame can serve as a grounding electrode has been changed again, and the requirements for concrete encased electrodes, ground rods, and ground plates have been clarified.
250.52 Grounding Electrode Types.
(A) Electrodes Permitted for Grounding.
(1) Underground Metal Water Pipe Electrode. Underground metal water pipe in direct contact with the earth for 10 ft or more can serve as a grounding electrode.
(2) Metal Frame Electrode. The metal frame of a building/structure can serve as a grounding electrode when it meets at least one of the following conditions:
(1) At least one structural metal member is in direct contact with the earth for 10 ft or more, with or without concrete encasement.
(2) The bolts securing the structural steel column are connected to a concrete encased electrode [250.52(A)(3)] by welding, exothermic welding, steel tie wires, or other approved means. (Fig. 7)
(3) Concrete-Encased Electrode. At least 20 ft of either (1) or (2):
(1) One or more of bare, zinc-galvanized, or otherwise electrically conductive steel reinforcing bars of not less than ½ in. diameter, mechanically connected together by steel tie wires, welding, or other effective means, to create a 20 ft or greater length.
(2) Bare copper conductor not smaller than 4 AWG.
The reinforcing bars or bare copper conductor must be encased by at least 2 in. of concrete located horizontally near the bottom of a concrete footing or vertically within a concrete foundation that's in direct contact with the earth.
If multiple concrete-encased electrodes are present at a building/structure, only one is required to serve as a grounding electrode
Note: Concrete containing insulation, vapor barriers, films or similar items separating it from the earth isn't considered to be in “direct contact” with the earth.
(4) Ground Ring Electrode. A ground ring consisting of at least 20 ft of bare copper conductor not smaller than 2 AWG buried in the earth encircling a building/structure can serve as a grounding electrode.
(5) Ground Rod and Pipe Electrode. Ground rod electrodes must not be less than 8 ft in length in contact with the earth [250.53(G)].
(b) Rod-type electrodes must have a diameter of at least ⅝ in., unless listed.
(6) Listed Electrode. Other listed grounding electrodes.
(7) Ground Plate Electrode. A bare or conductively coated iron or steel plate with not less than ¼ in. of thickness, or a solid uncoated copper metal plate not less than 0.06 in. of thickness, with an exposed surface area of not less than 2 sq ft.
(8) Metal Underground Systems Electrode. Metal underground piping systems, underground tanks, and underground metal well casings can serve as a grounding electrode.
Analysis: Over the last few Code cycles, the NEC has tried to make clear when the structural metal of a building or structure can be used as a grounding electrode. The first prescribed method will find the structural metal with direct earth contact for 10 ft or more. As an alternative, the hold-down bolts securing the structural metal column can be connected to a concrete-encased electrode. Previously, the Code allowed the structural metal to serve as an electrode if it was connected to a ground rod meeting the 25-ohm requirement of (formerly) 250.56. This option has now been removed and is no longer a suitable method of bonding the structural metal to qualify it as a grounding electrode.
The ways of creating a concrete-encased electrode have been changed into an easy-to-use list format, and a clarification has been made regarding the use of vapor barriers.
When a vapor barrier (typically a plastic sheet) is installed beneath the footing, NEC users have debated whether or not the concrete is still considered to be in direct contact with earth. A new Informational Note was added to clarify that such a footing isn't considered to be in direct contact with the earth; therefore, the rebar or bare copper conductor can't be used as a grounding electrode.
Section 250.52(A)(5) has been changed to eliminate the minimum size for listed electrodes. Previous editions of the Code have stated that listed ground rods must be at least ½ in. in diameter. Because the NEC is typically not the place to find listing requirements, this text has been removed, which might open the door to smaller ground rods being listed.
Lastly, a change was made to 250.52(A)(7), which clarifies that plate electrodes must be conductive(!).
To be continued next month.