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Article 314

Outlet, Device, Pull, and Junction Boxes; Conduit Bodies; Fittings; and Handhole Enclosures

Part I. Scope and General

  1. Scope. This article covers the installation and use of all boxes and conduit bodies used as outlet, device, junction, or pull boxes, depending on their use, and handhole enclosures. Cast metal, sheet metal, nonmetallic, and other boxes such as FS, FD, and larger boxes are not classified as conduit bodies. This article also includes installation requirements for fittings used to join raceways and to connect raceways and cables to boxes and conduit bodies.
  2. Round Boxes. Round boxes shall not be used where conduits or connectors requiring the use of locknuts or bush‐ ings are to be connected to the side of the box.
  3. Nonmetallic Boxes. Nonmetallic boxes shall be permit‐ ted only with open wiring on insulators, concealed knob-and- tube wiring, cabled wiring methods with entirely nonmetallic sheaths, flexible cords, and nonmetallic raceways.Exception No. 1: Where internal bonding means are provided between all entries, nonmetallic boxes shall be permitted to be used with metal raceways or metal-armored cables.Exception No. 2: Where integral bonding means with a provision for attaching an equipment bonding jumper inside the box are provided between all threaded entries in nonmetallic boxes listed for the purpose, nonmetallic boxes shall be permitted to be used with metal raceways or metal-armored cables.
  4. Metal Boxes. Metal boxes shall be grounded and bonded in accordance with Parts I, IV, V, VI, VII, and X of Arti‐ cle 250 as applicable, except as permitted in 250.112(I).

Part II. Installation

  1. Damp or Wet Locations. In damp or wet locations, boxes, conduit bodies, outlet box hoods, and fittings shall be placed or equipped so as to prevent moisture from entering or accumulating within the box, conduit body, or fitting. Boxes, conduit bodies, outlet box hoods, and fittings installed in wet locations shall be listed for use in wet locations. Approved drainage openings not smaller than 3 mm (1∕8 in.) and not larger than 6 mm (1∕4 in.) in diameter shall be permitted to be installed in the field in boxes or conduit bodies listed for use in damp or wet locations. For installation of listed drain fittings, larger openings are permitted to be installed in the field in accordance with manufacturer’s instructions.Informational Note No. 1: For boxes in floors, see 314.27(B).Informational Note No. 2: For protection against corrosion, see 300.6.
  2. Number of Conductors in Outlet, Device, and Junction Boxes, and Conduit Bodies. Boxes and conduit bodies shall be of an approved size to provide free space for all enclosed conductors. In no case shall the volume of the box, as calcula‐ ted in 314.16(A), be less than the fill calculation as calculatedin 314.16(B). The minimum volume for conduit bodies shall be as calculated in 314.16(C).The provisions of this section shall not apply to terminal housings supplied with motors or generators.Informational Note: For volume requirements of motor or generator terminal housings, see 430.12.Boxes and conduit bodies enclosing conductors 4 AWG or larger shall also comply with the provisions of 314.28.
    1. Box Volume Calculations. The volume of a wiring enclo‐ sure (box) shall be the total volume of the assembled sections and, where used, the space provided by plaster rings, domed covers, extension rings, and so forth, that are marked with their volume or are made from boxes the dimensions of which are listed in Table 314.16(A). Where a box is provided with one or more securely installed barriers, the volume shall be appor‐ tioned to each of the resulting spaces. Each barrier, if not marked with its volume, shall be considered to take up 8.2 cm3 (1∕2 in3) if metal, and 16.4 cm3 (1.0 in3) if nonmetallic.
      1. Standard Boxes. The volumes of standard boxes that are not marked with their volume shall be as given in Table 314.16(A).
      2. Other Boxes. Boxes 1650 cm3 (100 in.3) or less, other than those described in Table 314.16(A), and nonmetallic boxes shall be durably and legibly marked by the manufacturer with their volume(s). Boxes described in Table 314.16(A) that have a volume larger than is designated in the table shall be permitted to have their volume marked as required by this section.
    2. Box Fill Calculations. The volumes in paragraphs 314.16(B)(1) through (B)(5), as applicable, shall be added together. No allowance shall be required for small fittings such as locknuts and bushings. Each space within a box installed with a barrier shall be calculated separately.
      1. Conductor Fill. Each conductor that originates outside the box and terminates or is spliced within the box shall be counted once, and each conductor that passes through the box without splice or termination shall be counted once. Each loop or coil of unbroken conductor not less than twice the mini‐ mum length required for free conductors in 300.14 shall be counted twice. The conductor fill shall be calculated using Table 314.16(B). A conductor, no part of which leaves the box, shall not be counted.Exception: An equipment grounding conductor or conductors or not over four fixture wires smaller than 14 AWG, or both, shall be permitted to be omitted from the calculations where they enter a box from a domed luminaire or similar canopy and terminate within that box.
      2. Clamp Fill. Where one or more internal cable clamps, whether factory or field supplied, are present in the box, a single volume allowance in accordance with Table 314.16(B) shall be made based on the largest conductor present in the box. No allowance shall be required for a cable connector with its clamping mechanism outside the box.A clamp assembly that incorporates a cable termination for the cable conductors shall be listed and marked for use with specific nonmetallic boxes. Conductors that originate within the clamp assembly shall be included in conductor fill calcula‐ tions covered in 314.16(B)(1) as though they entered from outside the box. The clamp assembly shall not require a fill
        Table 314.16(A) Metal Boxes

        Box Trade SizeMinimum VolumeMaximum Number of Conductors* (arranged by AWG size)mmin.
        cm3in.3181614121086100 × 32(4 × 11∕4)round/octagonal20512.58765552100 × 38(4 × 11∕2)round/octagonal25415.510876653100 × 54(4 × 21∕8)round/octagonal35321.51412109874100 × 32(4× 11∕4)square29518.0121098763100 × 38(4 × 11∕2)square34421.01412109874100 × 54(4 × 21∕8)square49730.32017151312106120 × 32(411∕16 × 11∕4)square41825.5171412111085120 × 38(411∕16 × 11∕2)square48429.5191614131195120 × 54(411∕16 × 21∕8)square68942.0282421181614875 × 50 × 38(3 × 2 × 11∕2)device1237.5543332175 × 50 × 50(3 × 2 × 2)device16410.0655443275× 50 × 57(3× 2 × 21∕4)device17210.5765443275 × 50 × 65(3 × 2 × 21∕2)device20512.5876554275 × 50 × 70(3 × 2 × 23∕4)device23014.0987654275 × 50 × 90(3 × 2 × 31∕2)device29518.0121098763100 × 54 × 38(4 × 21∕8 × 11∕2)device16910.36554432100 × 54 × 48(4 × 21∕8 × 17∕8)device21313.08765542100 × 54 × 54(4 × 21∕8 × 21∕8)device23814.5987654295 × 50 × 65(33∕4 × 2 × 21∕2)masonry box23014.0987654295 × 50 × 90(33∕4 × 2 × 31∕2)masonry box34421.01412109874min. 44.5 depth FS — single cover (13∕4)22113.59766542min. 60.3 depth FD — single cover (23∕8)29518.0121098763min. 44.5 depth FS — multiple cover (13∕4)29518.0121098763min. 60.3 depth FD — multiple cover (23∕8)39524.016131210984*Where no volume allowances are required by 314.16(B)(2) through (B)(5).
        allowance, but the volume of the portion of the assembly that Table 314.16(B) Volume Allowance Required per Conductorremains within the box after installation shall be excluded from                                                                                                                                the box volume as marked in 314.16(A)(2).
      3. Support Fittings Fill. Where one or more luminaire studs or hickeys are present in the box, a single volume allowance in accordance with Table 314.16(B) shall be made for each type
        imageSize of Conductor (AWG)Free Space Within Box for Each Conductorimagecm3 in.3of fitting based on the largest conductor present in the box.
      4. Device or Equipment Fill. For each yoke or strap contain‐ ing one or more devices or equipment, a double volume allow‐ ance in accordance with Table 314.16(B) shall be made for each yoke or strap based on the largest conductor connected to a device(s) or equipment supported by that yoke or strap. A device or utilization equipment wider than a single 50 mm (2 in.) device box as described in Table 314.16(A) shall have double volume allowances provided for each gang required for mounting.
      5. Equipment Grounding Conductor Fill. Where one or more equipment grounding conductors or equipment bonding jumpers enter a box, a single volume allowance in accordance with Table 314.16(B) shall be made based on the largest equip‐ ment grounding conductor or equipment bonding jumper present in the box. Where an additional set of equipment grounding conductors, as permitted by 250.146(D), is present in the box, an additional volume allowance shall be made based on the largest equipment grounding conductor in the additional set.18 24.6 1.5016 28.7 1.7514 32.8 2.0012 36.9 2.2510 41.0 2.508 49.2 3.006 81.9 5.00
    3. Conduit Bodies.
      1. General. Conduit bodies enclosing 6 AWG conductors or smaller, other than short-radius conduit bodies as described in 314.16(C)(3), shall have a cross-sectional area not less than twice the cross-sectional area of the largest conduit or tubing to which they can be attached. The maximum number of conduc‐ tors permitted shall be the maximum number permitted by Table 1 of Chapter 9 for the conduit or tubing to which it is attached.
      2. With Splices, Taps, or Devices. Only those conduit bodies that are durably and legibly marked by the manufacturer with their volume shall be permitted to contain splices, taps, or devi‐
        ces. The maximum number of conductors shall be calculated in accordance with 314.16(B). Conduit bodies shall be suppor‐ ted in a rigid and secure manner.
      3. Short Radius Conduit Bodies. Conduit bodies such as capped elbows and service-entrance elbows that enclose conductors 6 AWG or smaller, and are only intended to enable the installation of the raceway and the contained conductors, shall not contain splices, taps, or devices and shall be of an approved size to provide free space for all conductors enclosed in the conduit body.
  3. Conductors Entering Boxes, Conduit Bodies, or Fittings. Conductors entering boxes, conduit bodies, or fittings shall be protected from abrasion and shall comply with 314.17(A) through (D).
  1. Openings to Be Closed. Openings through which conductors enter shall be closed in an approved manner.
  2. Metal Boxes and Conduit Bodies. Where metal boxes or conduit bodies are installed with messenger-supported wiring, open wiring on insulators, or concealed knob-and-tube wiring, conductors shall enter through insulating bushings or, in dry locations, through flexible tubing extending from the last insu‐ lating support to not less than 6 mm (1∕4 in.) inside the box and beyond any cable clamps. Where nonmetallic-sheathed cable or multiconductor Type UF cable is used, the sheath shall extend not less than 6 mm (1∕4 in.) inside the box and beyond any cable clamp. Except as provided in 300.15(C), the wiring shall be firmly secured to the box or conduit body. Where raceway or cable is installed with metal boxes or conduit bodies, the raceway or cable shall be secured to such boxes and conduit bodies.
  3. Nonmetallic Boxes and Conduit Bodies. Nonmetallic boxes and conduit bodies shall be suitable for the lowest temperature-rated conductor entering the box. Where nonme‐ tallic boxes and conduit bodies are used with messenger- supported wiring, open wiring on insulators, or concealed knob-and-tube wiring, the conductors shall enter the box through individual holes. Where flexible tubing is used to enclose the conductors, the tubing shall extend from the last insulating support to not less than 6 mm (1∕4 in.) inside the box and beyond any cable clamp. Where nonmetallic-sheathed cable or multiconductor Type UF cable is used, the sheath shall extend not less than 6 mm (1∕4 in.) inside the box and beyond any cable clamp. In all instances, all permitted wiring methods shall be secured to the boxes.Exception: Where nonmetallic-sheathed cable or multiconductor Type UF cable is used with single gang boxes not larger than a nominal size 57 mm × 100 mm (21∕4 in. × 4 in.) mounted in walls or ceilings, and where the cable is fastened within 200 mm (8 in.) of the box meas‐ ured along the sheath and where the sheath extends through a cable knockout not less than 6 mm (1∕4 in.), securing the cable to the box shall not be required. Multiple cable entries shall be permitted in a single cable knockout opening.
  4. Conductors 4 AWG or Larger. Installation shall comply with 300.4(G).

Informational Note: See 110.12(A) for requirements on closing unused cable and raceway knockout openings.

  1. Boxes Enclosing Flush Devices. Boxes used to enclose flush devices shall be of such design that the devices will be completely enclosed on back and sides and substantial supportfor the devices will be provided. Screws for supporting the box shall not also be used to attach a device.
  2. Flush-Mounted Installations. Installations within or behind a surface of concrete, tile, gypsum, plaster, or other noncombustible material, including boxes employing a flush- type cover or faceplate, shall be made so that the front edge of the box, plaster ring, extension ring, or listed extender will not be set back of the finished surface more than 6 mm (1∕4 in.).Installations within a surface of wood or other combustible surface material, boxes, plaster rings, extension rings, or listed extenders shall extend to the finished surface or project there‐ from.
  3. Repairing Noncombustible Surfaces. Noncombustible surfaces that are broken or incomplete around boxes employ‐ ing a flush-type cover or faceplate shall be repaired so there will be no gaps or open spaces greater than 3 mm (1∕8 in.) at the edge of the box.
  4. Surface Extensions. Surface extensions shall be made by mounting and mechanically securing an extension ring over the box. Equipment grounding shall be in accordance with Part VI of Article 250.Exception: A surface extension shall be permitted to be made from the cover of a box where the cover is designed so it is unlikely to fall off or be removed if its securing means becomes loose. The wiring method shall be flexible for an approved length that permits removal of the cover and provides access to the box interior and shall be arranged so that any grounding continuity is independent of the connection between the box and cover.
  5. Supports. Enclosures within the scope of this article shall be supported in accordance with one or more of the provisions in 314.23(A) through (H).
    1. Surface Mounting. An enclosure mounted on a building or other surface shall be rigidly and securely fastened in place. If the surface does not provide rigid and secure support, addi‐ tional support in accordance with other provisions of this section shall be provided.
    2. Structural Mounting. An enclosure supported from a structural member or from grade shall be rigidly supported either directly or by using a metal, polymeric, or wood brace.
      1. Nails and Screws. Nails and screws, where used as a fasten‐ ing means, shall secure boxes by using brackets on the outside of the enclosure, or by using mounting holes in the back or in a single side of the enclosure, or they shall pass through the interior within 6 mm (1∕4 in.) of the back or ends of the enclo‐ sure. Screws shall not be permitted to pass through the box unless exposed threads in the box are protected using approved means to avoid abrasion of conductor insulation. Mounting holes made in the field shall be approved.
      2. Braces. Metal braces shall be protected against corrosion and formed from metal that is not less than 0.51 mm (0.020 in.) thick uncoated. Wood braces shall have a cross section not less than nominal 25 mm × 50 mm (1 in. × 2 in.). Wood braces in wet locations shall be treated for the condi‐ tions. Polymeric braces shall be identified as being suitable for the use.
    3. Mounting in Finished Surfaces. An enclosure mounted in a finished surface shall be rigidly secured thereto by clamps, anchors, or fittings identified for the application.
    4. Suspended Ceilings. An enclosure mounted to structural or supporting elements of a suspended ceiling shall be not more than 1650 cm3 (100 in.3) in size and shall be securely fastened in place in accordance with either 314.23(D)(1) or (D)(2).
      1. Framing Members. An enclosure shall be fastened to the framing members by mechanical means such as bolts, screws, or rivets, or by the use of clips or other securing means identi‐
      2. The unbroken conduit length before the last point of conduit support is 300 mm (12 in.) or greater, and that portion of the conduit is securely fastened at some point not less than 300 mm (12 in.) from its last point of support.
      3. Where accessible to unqualified persons, the luminaire or lamp‐ holder, measured to its lowest point, is at least 2.5 m (8 ft) above grade or standing area and at least 900 mm (3 ft) measured horizontally to the 2.5 m (8 ft) elevation from windows, doors,fied for use with the type of ceiling framing member(s) and enclosure(s) employed. The framing members shall be suppor‐ ted in an approved manner and securely fastened to each other and to the building structure.(2) Support Wires. The installation shall comply with the(4)
        (5)porches, fire escapes, or similar locations.A luminaire supported by a single conduit does not exceed 300 mm (12 in.) in any direction from the point of conduit entry.The weight supported by any single conduit does not exceed 9 kg (20 lb).provisions of 300.11(A). The enclosure shall be secured, using identified methods, to ceiling support wire(s), including any additional support wire(s) installed for ceiling support. Support wire(s) used for enclosure support shall be fastened at each end so as to be taut within the ceiling cavity.
    5. Raceway-Supported Enclosure, Without Devices, Lumin‐ aires, or Lampholders. An enclosure that does not contain a device(s), other than splicing devices, or supports a lumin‐ aire(s), a lampholder, or other equipment and is supported by entering raceways shall not exceed 1650 cm3 (100 in.3) in size. It shall have threaded entries or identified hubs. It shall be supported by two or more conduits threaded wrenchtight into the enclosure or hubs. Each conduit shall be secured within 900 mm (3 ft) of the enclosure, or within 450 mm (18 in.) of the enclosure if all conduit entries are on the same side.Exception: The following wiring methods shall be permitted to support a conduit body of any size, including a conduit body constructed with only one conduit entry, provided that the trade size of the conduit body is not larger than the largest trade size of the conduit or tubing:
      1. Intermediate metal conduit, Type IMC
      2. Rigid metal conduit, Type RMC
      3. Rigid polyvinyl chloride conduit, Type PVC
      4. Reinforced thermosetting resin conduit, Type RTRC
      5. Electrical metallic tubing, Type EMT
    6. Raceway-Supported Enclosures, with Devices, Luminaires, or Lampholders. An enclosure that contains a device(s), other than splicing devices, or supports a luminaire(s), a lampholder, or other equipment and is supported by entering raceways shall not exceed 1650 cm3 (100 in.3) in size. It shall have threaded entries or identified hubs. It shall be supported by two or more conduits threaded wrenchtight into the enclosure or hubs. Each conduit shall be secured within 450 mm (18 in.) of the enclosure.Exception No. 1: Rigid metal or intermediate metal conduit shall be permitted to support a conduit body of any size, including a conduit body constructed with only one conduit entry, provided the trade size of the conduit body is not larger than the largest trade size of the conduit.Exception No. 2: An unbroken length(s) of rigid or intermediate metal conduit shall be permitted to support a box used for luminaire or lamp‐ holder support, or to support a wiring enclosure that is an integral part of a luminaire and used in lieu of a box in accordance with 300.15(B), where all of the following conditions are met:(1) The conduit is securely fastened at a point so that the length of conduit beyond the last point of conduit support does not exceed 900 mm (3 ft).
      1. At the luminaire or lampholder end, the conduit(s) is threaded wrenchtight into the box, conduit body, integral wiring enclosure, or identified hubs. Where a box or conduit body is used for support, the luminaire shall be secured directly to the box or conduit body, or through a threaded conduit nipple not over 75 mm (3 in.) long.
    7. Enclosures in Concrete or Masonry. An enclosure supported by embedment shall be identified as suitably protec‐ ted from corrosion and securely embedded in concrete or masonry.
    8. Pendant Boxes. An enclosure supported by a pendant shall comply with 314.23(H)(1) or (H)(2).
      1. Flexible Cord. A box shall be supported from a multicon‐ ductor cord or cable in an approved manner that protects the conductors against strain, such as a strain-relief connector threaded into a box with a hub.
      2. Conduit. A box supporting lampholders or luminaires, or wiring enclosures within luminaires used in lieu of boxes in accordance with 300.15(B), shall be supported by rigid or inter‐ mediate metal conduit stems. For stems longer than 450 mm (18 in.), the stems shall be connected to the wiring system with flexible fittings suitable for the location. At the luminaire end, the conduit(s) shall be threaded wrenchtight into the box, wiring enclosure, or identified hubs.
    Where supported by only a single conduit, the threaded joints shall be prevented from loosening by the use of set- screws or other effective means, or the luminaire, at any point, shall be at least 2.5 m (8 ft) above grade or standing area and at least 900 mm (3 ft) measured horizontally to the 2.5 m (8 ft) elevation from windows, doors, porches, fire escapes, or similar locations. A luminaire supported by a single conduit shall not exceed 300 mm (12 in.) in any horizontal direction from the point of conduit entry.
  6. Depth of Boxes. Outlet and device boxes shall have an approved depth to allow equipment installed within them to be mounted properly and without likelihood of damage to conductors within the box.
    1. Outlet Boxes Without Enclosed Devices or Utilization Equipment. Outlet boxes that do not enclose devices or utilization equipment shall have a minimum internal depth of12.7 mm (1∕2 in.).
    2. Outlet and Device Boxes with Enclosed Devices or Utiliza‐ tion Equipment. Outlet and device boxes that enclose devices or utilization equipment shall have a minimum internal depth that accommodates the rearward projection of the equipment and the size of the conductors that supply the equipment. The
      internal depth shall include, where used, that of any extension boxes, plaster rings, or raised covers. The internal depth shall comply with all applicable provisions of 314.24(B)(1) through (B)(5).
      1. Large Equipment. Boxes that enclose devices or utiliza‐ tion equipment that projects more than 48 mm (17∕8 in.) rear‐ ward from the mounting plane of the box shall have a depth that is not less than the depth of the equipment plus 6 mm (1∕4 in.).
      2. Conductors Larger Than 4 AWG. Boxes that enclose devi‐ ces or utilization equipment supplied by conductors larger than 4 AWG shall be identified for their specific function.Exception to (2): Devices or utilization equipment supplied by conduc‐ tors larger than 4 AWG shall be permitted to be mounted on or in junc‐ tion and pull boxes larger than 1650 cm3 (100 in.3) if the spacing at the terminals meets the requirements of 312.6.
      3. Conductors 8, 6, or 4 AWG. Boxes that enclose devices or utilization equipment supplied by 8, 6, or 4 AWG conductors shall have an internal depth that is not less than 52.4 mm (21∕16 in.).
      4. Conductors 12 or 10 AWG. Boxes that enclose devices or utilization equipment supplied by 12 or 10 AWG conductors shall have an internal depth that is not less than 30.2 mm (13∕16 in.). Where the equipment projects rearward from the mounting plane of the box by more than 25 mm (1 in.), the box shall have a depth not less than that of the equipment plus 6 mm (1∕4 in.).
      5. Conductors 14 AWG and Smaller. Boxes that enclose devi‐ ces or utilization equipment supplied by 14 AWG or smaller conductors shall have a depth that is not less than 23.8 mm (15∕16 in.).
    Exception to (1) through (5): Devices or utilization equipment that is listed to be installed with specified boxes shall be permitted.
  7. Covers and Canopies. In completed installations, each box shall have a cover, faceplate, lampholder, or luminaire canopy, except where the installation complies with 410.24(B). Screws used for the purpose of attaching covers, or other equipment, to the box shall be either machine screws matching the thread gauge or size that is integral to the box or shall be in accordance with the manufacturer’s instructions.
  1. Nonmetallic or Metal Covers and Plates. Nonmetallic or metal covers and plates shall be permitted. Where metal covers or plates are used, they shall comply with the grounding requirements of 250.110.Informational Note: For additional grounding requirements, see410.42 for metal luminaire canopies, and 404.12 and 406.6(B) for metal faceplates.
  2. Exposed Combustible Wall or Ceiling Finish. Where a luminaire canopy or pan is used, any combustible wall or ceil‐ ing finish exposed between the edge of the canopy or pan and the outlet box shall be covered with noncombustible material if required by 410.23.
  3. Flexible Cord Pendants. Covers of outlet boxes and conduit bodies having holes through which flexible cord pend‐ ants pass shall be provided with identified bushings or shall have smooth, well-rounded surfaces on which the cords may

bear. So-called hard rubber or composition bushings shall not be used.

314.27 Outlet Boxes.

  1. Boxes at Luminaire or Lampholder Outlets. Outlet boxes or fittings designed for the support of luminaires and lamp‐ holders, and installed as required by 314.23, shall be permitted to support a luminaire or lampholder.
    1. Vertical Surface Outlets. Boxes used at luminaire or lamp‐ holder outlets in or on a vertical surface shall be identified and marked on the interior of the box to indicate the maximum weight of the luminaire that is permitted to be supported by the box if other than 23 kg (50 lb).Exception: A vertically mounted luminaire or lampholder weighing not more than 3 kg (6 lb) shall be permitted to be supported on other boxes or plaster rings that are secured to other boxes, provided that the lumin‐ aire or its supporting yoke, or the lampholder, is secured to the box with no fewer than two No. 6 or larger screws.
    2. Ceiling Outlets. At every outlet used exclusively for light‐ ing, the box shall be designed or installed so that a luminaire or lampholder may be attached. Boxes shall be required to support a luminaire weighing a minimum of 23 kg (50 lb). A luminaire that weighs more than 23 kg (50 lb) shall be suppor‐ ted independently of the outlet box, unless the outlet box is listed for not less than the weight to be supported. The interior of the box shall be marked by the manufacturer to indicate the maximum weight the box shall be permitted to support.
  2. Floor Boxes. Boxes listed specifically for this application shall be used for receptacles located in the floor.Exception: Where the authority having jurisdiction judges them free from likely exposure to physical damage, moisture, and dirt, boxes loca‐ ted in elevated floors of show windows and similar locations shall be permitted to be other than those listed for floor applications. Receptacles and covers shall be listed as an assembly for this type of location.
  3. Boxes at Ceiling-Suspended (Paddle) Fan Outlets. Outlet boxes or outlet box systems used as the sole support of a ceiling-suspended (paddle) fan shall be listed, shall be marked by their manufacturer as suitable for this purpose, and shall not support ceiling-suspended (paddle) fans that weigh more than 32 kg (70 lb). For outlet boxes or outlet box systems designed to support ceiling-suspended (paddle) fans that weigh more than 16 kg (35 lb), the required marking shall include the maximum weight to be supported.Where spare, separately switched, ungrounded conductors are provided to a ceiling-mounted outlet box, in a location acceptable for a ceiling-suspended (paddle) fan in one-family, two-family, or multifamily dwellings, the outlet box or outlet box system shall be listed for sole support of a ceiling- suspended (paddle) fan.
  4. Utilization Equipment. Boxes used for the support of utilization equipment other than ceiling-suspended (paddle) fans shall meet the requirements of 314.27(A) for the support of a luminaire that is the same size and weight.Exception: Utilization equipment weighing not more than 3 kg (6 lb) shall be permitted to be supported on other boxes or plaster rings that are secured to other boxes, provided the equipment or its supporting yoke is secured to the box with no fewer than two No. 6 or larger screws.
    imageN
  5. Separable Attachment Fittings. Outlet boxes required in
  1. shall be permitted to support listed locking support and mounting receptacles used in combination with compatible attachment fittings. The combination shall be identified for the support of equipment within the weight and mounting orienta‐ tion limits of the listing. Where the supporting receptacle is installed within a box, it shall be included in the fill calculation covered in 314.16(B)(4).
  2. Pull and Junction Boxes and Conduit Bodies. Boxes and conduit bodies used as pull or junction boxes shall comply with 314.28(A) through (E).Exception: Terminal housings supplied with motors shall comply with the provisions of 430.12.
    1. Minimum Size. For raceways containing conductors of 4 AWG or larger that are required to be insulated, and for cables containing conductors of 4 AWG or larger, the minimum dimensions of pull or junction boxes installed in a raceway or cable run shall comply with 314.28(A)(1) through (A)(3). Where an enclosure dimension is to be calculated based on the diameter of entering raceways, the diameter shall be the metric designator (trade size) expressed in the units of measurement employed.
      1. Straight Pulls. In straight pulls, the length of the box or conduit body shall not be less than eight times the metric desig‐ nator (trade size) of the largest raceway.
      2. Angle or U Pulls, or Splices. Where splices or where angle or U pulls are made, the distance between each raceway entry inside the box or conduit body and the opposite wall of the box or conduit body shall not be less than six times the metric designator (trade size) of the largest raceway in a row. This distance shall be increased for additional entries by the amount of the sum of the diameters of all other raceway entries in the same row on the same wall of the box. Each row shall be calcu‐ lated individually, and the single row that provides the maxi‐ mum distance shall be used.Exception: Where a raceway or cable entry is in the wall of a box or conduit body opposite a removable cover, the distance from that wall to the cover shall be permitted to comply with the distance required for one wire per terminal in Table 312.6(A).The distance between raceway entries enclosing the same conductor shall not be less than six times the metric designator (trade size) of the larger raceway.When transposing cable size into raceway size in 314.28(A)(1) and (A)(2), the minimum metric designator (trade size) raceway required for the number and size of conductors in the cable shall be used.
      3. Smaller Dimensions. Listed boxes or listed conduit bodies of dimensions less than those required in 314.28(A)(1) and (A)(2) shall be permitted for installations of combinations of conductors that are less than the maximum conduit or tubing fill (of conduits or tubing being used) permitted by Table 1 of Chapter 9.Listed conduit bodies of dimensions less than those required in 314.28(A)(2), and having a radius of the curve to the center‐ line not less than that indicated in Table 2 of Chapter 9 for one-shot and full-shoe benders, shall be permitted for installa‐ tions of combinations of conductors permitted by Table 1 of Chapter 9. These conduit bodies shall be marked to show theyhave been specifically evaluated in accordance with this provi‐ sion.Where the permitted combinations of conductors for which the box or conduit body has been listed are less than the maxi‐ mum conduit or tubing fill permitted by Table 1 of Chapter 9, the box or conduit body shall be permanently marked with the maximum number and maximum size of conductors permit‐ ted. For other conductor sizes and combinations, the total cross-sectional area of the fill shall not exceed the cross- sectional area of the conductors specified in the marking, based on the type of conductor identified as part of the prod‐ uct listing.
        Informational Note: Unless otherwise specified, the applicableproduct standards evaluate the fill markings covered here based on conductors with Type XHHW insulation.
    2. Conductors in Pull or Junction Boxes. In pull boxes or junction boxes having any dimension over 1.8 m (6 ft), all conductors shall be cabled or racked up in an approved manner.
    3. Covers. All pull boxes, junction boxes, and conduit bodies shall be provided with covers compatible with the box or conduit body construction and suitable for the conditions of use. Where used, metal covers shall comply with the grounding requirements of 250.110.
    4. Permanent Barriers. Where permanent barriers are installed in a box, each section shall be considered as a sepa‐ rate box.
    5. Power Distribution Blocks. Power distribution blocks shall be permitted in pull and junction boxes over 1650 cm3 (100 in.3) for connections of conductors where installed in boxes and where the installation complies with 314.28(E)(1) through (5).Exception: Equipment grounding terminal bars shall be permitted in smaller enclosures.
      1. Installation. Power distribution blocks installed in boxes shall be listed. Power distribution blocks installed on the line side of the service equipment shall be listed and marked “suita‐ ble for use on the line side of service equipment” or equivalent.
      2. Size. In addition to the overall size requirement in the first sentence of 314.28(A)(2), the power distribution block shall be installed in a box with dimensions not smaller than specified in the installation instructions of the power distribu‐ tion block.
      3. Wire Bending Space. Wire bending space at the terminals of power distribution blocks shall comply with 312.6.
      4. Live Parts. Power distribution blocks shall not have unin‐ sulated live parts exposed within a box, whether or not the box cover is installed.
      5. Through Conductors. Where the pull or junction boxes are used for conductors that do not terminate on the power distribution block(s), the through conductors shall be arranged so the power distribution block terminals are unob‐ structed following installation.
  3. Boxes, Conduit Bodies, and Handhole Enclosures to Be Accessible. Boxes, conduit bodies, and handhole enclo‐ sures shall be installed so that the wiring contained in them can be rendered accessible without removing any part of the build‐
    ing or structure or, in underground circuits, without excavating sidewalks, paving, earth, or other substance that is to be used to establish the finished grade.Exception: Listed boxes and handhole enclosures shall be permitted where covered by gravel, light aggregate, or noncohesive granulated soil if their location is effectively identified and accessible for excavation.
  4. Handhole Enclosures. Handhole enclosures shall be designed and installed to withstand all loads likely to be imposed on them. They shall be identified for use in under‐ ground systems.

Informational Note: See ANSI/SCTE 77-2002, Specification for Underground Enclosure Integrity, for additional information on deliberate and nondeliberate traffic loading that can be expec‐ ted to bear on underground enclosures.

  1. Size. Handhole enclosures shall be sized in accordance with 314.28(A) for conductors operating at 1000 volts or below, and in accordance with 314.71 for conductors operating at over 1000 volts. For handhole enclosures without bottoms where the provisions of 314.28(A)(2), Exception, or 314.71(B)(1), Excep‐ tion No. 1, apply, the measurement to the removable cover shall be taken from the end of the conduit or cable assembly.
  2. Wiring Entries. Underground raceways and cable assem‐ blies entering a handhole enclosure shall extend into the enclosure, but they shall not be required to be mechanically connected to the enclosure.
  3. Enclosed Wiring. All enclosed conductors and any splices or terminations, if present, shall be listed as suitable for wet locations.
  4. Covers. Handhole enclosure covers shall have an identify‐ ing mark or logo that prominently identifies the function of the enclosure, such as “electric.” Handhole enclosure covers shall require the use of tools to open, or they shall weigh over 45 kg (100 lb). Metal covers and other exposed conductive surfaces shall be bonded in accordance with 250.92 if the conductors in the handhole are service conductors, or in accordance with 250.96(A) if the conductors in the handhole are feeder or branch-circuit conductors.

Part III. Construction Specifications

  1. Metal Boxes, Conduit Bodies, and Fittings.
    1. Corrosion Resistant. Metal boxes, conduit bodies, and fittings shall be corrosion resistant or shall be well-galvanized, enameled, or otherwise properly coated inside and out to prevent corrosion.Informational Note: See 300.6 for limitation in the use of boxes and fittings protected from corrosion solely by enamel.
    2. Thickness of Metal. Sheet steel boxes not over 1650 cm3 (100 in.3) in size shall be made from steel not less than1.59 mm (0.0625 in.) thick. The wall of a malleable iron box or conduit body and a die-cast or permanent-mold cast aluminum, brass, bronze, or zinc box or conduit body shall not be less than 2.38 mm (3∕32 in.) thick. Other cast metal boxes or conduitbodies shall have a wall thickness not less than 3.17 mm (1∕8 in.).Exception No. 1: Listed boxes and conduit bodies shown to have equiv‐ alent strength and characteristics shall be permitted to be made of thin‐ ner or other metals.Exception No. 2: The walls of listed short radius conduit bodies, as covered in 314.16(C)(2), shall be permitted to be made of thinner metal.
    3. Metal Boxes Over 1650 cm3 (100 in.3). Metal boxes over 1650 cm3 (100 in.3) in size shall be constructed so as to be of ample strength and rigidity. If of sheet steel, the metal thick‐ ness shall not be less than 1.35 mm (0.053 in.) uncoated.
    4. Grounding Provisions. A means shall be provided in each metal box for the connection of an equipment grounding conductor. The means shall be permitted to be a tapped hole or equivalent.
  2. Covers. Metal covers shall be of the same material as the box or conduit body with which they are used, or they shall be lined with firmly attached insulating material that is not less than 0.79 mm (1∕32 in.) thick, or they shall be listed for the purpose. Metal covers shall be the same thickness as the boxes or conduit body for which they are used, or they shall be listed for the purpose. Covers of porcelain or other approved insulat‐ ing materials shall be permitted if of such form and thickness as to afford the required protection and strength.
  3. Bushings. Covers of outlet boxes and conduit bodies having holes through which flexible cord pendants may pass shall be provided with approved bushings or shall have smooth, well-rounded surfaces on which the cord may bear. Where indi‐ vidual conductors pass through a metal cover, a separate hole equipped with a bushing of suitable insulating material shall be provided for each conductor. Such separate holes shall be connected by a slot as required by 300.20.
  4. Nonmetallic Boxes. Provisions for supports or other mounting means for nonmetallic boxes shall be outside of the box, or the box shall be constructed so as to prevent contact between the conductors in the box and the supporting screws.
  5. Marking. All boxes and conduit bodies, covers, exten‐ sion rings, plaster rings, and the like shall be durably and legi‐ bly marked with the manufacturer’s name or trademark.

Part IV. Pull and Junction Boxes, Conduit Bodies, and Hand‐ hole Enclosures for Use on Systems over 1000 Volts, Nominal

314.70 General.

  1. Pull and Junction Boxes. Where pull and junction boxes are used on systems over 1000 volts, the installation shall comply with the provisions of Part IV and with the following general provisions of this article:(1) Part I, 314.2; 314.3; and 314.4(2) Part II, 314.15; 314.17; 314.20; 314.23(A), (B), or (G);314.28(B); and 314.29(3) Part III, 314.40(A) and (C); and 314.41
  2. Conduit Bodies. Where conduit bodies are used on systems over 1000 volts, the installation shall comply with the provisions of Part IV and with the following general provisions of this article:(1) Part I, 314.4(2) Part II, 314.15; 314.17; 314.23(A), (E), or (G);314.28(A)(3); and 314.29(3) Part III, 314.40(A) and 314.41
    1. ARTICLE 320 — ARMORED CABLE: TYPE AC
  3. Handhole Enclosures. Where handhole enclosures are used on systems over 1000 volts, the installation shall comply with the provisions of Part IV and with the following general provisions of this article:

(1) Part I, 314.3 and 314.4

(2) Part II, 314.15; 314.17; 314.23(G); 314.28(B); 314.29; and

314.30

  1. Size of Pull and Junction Boxes, Conduit Bodies, and Handhole Enclosures. Pull and junction boxes and handhole enclosures shall provide approved space and dimensions for the installation of conductors, and they shall comply with the specific requirements of this section. Conduit bodies shall be permitted if they meet the dimensional requirements for boxes.•
    1. For Straight Pulls. The length of the box shall not be lessthan 48 times the outside diameter, over sheath, of the largest shielded or lead-covered conductor or cable entering the box. The length shall not be less than 32 times the outside diameter of the largest nonshielded conductor or cable.
    2. For Angle or U Pulls.
      1. Distance to Opposite Wall. The distance between each cable or conductor entry inside the box and the opposite wall of the box shall not be less than 36 times the outside diameter, over sheath, of the largest cable or conductor. This distance shall be increased for additional entries by the amount of the sum of the outside diameters, over sheath, of all other cables or conductor entries through the same wall of the box.Exception No. 1: Where a conductor or cable entry is in the wall of a box opposite a removable cover, the distance from that wall to the cover shall be permitted to be not less than the bending radius for the conduc‐ tors as provided in 300.34.Exception No. 2: Where cables are nonshielded and not lead covered, the distance of 36 times the outside diameter shall be permitted to be reduced to 24 times the outside diameter.
      2. Distance Between Entry and Exit. The distance between a cable or conductor entry and its exit from the box shall not be less than 36 times the outside diameter, over sheath, of that cable or conductor.Exception: Where cables are nonshielded and not lead covered, the distance of 36 times the outside diameter shall be permitted to be reduced to 24 times the outside diameter.
    3. Removable Sides. One or more sides of any pull box shall be removable.
  2. Construction and Installation Requirements.
  1. Corrosion Protection. Boxes shall be made of material inherently resistant to corrosion or shall be suitably protected, both internally and externally, by enameling, galvanizing, plat‐ ing, or other means.
  2. Passing Through Partitions. Suitable bushings, shields, or fittings having smooth, rounded edges shall be provided where conductors or cables pass through partitions and at other loca‐ tions where necessary.
  3. Complete Enclosure. Boxes shall provide a complete enclosure for the contained conductors or cables.
  4. Wiring Is Accessible. Boxes and conduit bodies shall be installed so that the conductors are accessible without remov‐ing any fixed part of the building or structure. Working space shall be provided in accordance with 110.34.
  5. Suitable Covers. Boxes shall be closed by suitable covers securely fastened in place. Underground box covers that weigh over 45 kg (100 lb) shall be considered meeting this require‐ ment. Covers for boxes shall be permanently marked “DANGER — HIGH VOLTAGE — KEEP OUT.” The marking shall be on the outside of the box cover and shall be readily visible. Letters shall be block type and at least 13 mm (1∕2 in.) in height.
  6. Suitable for Expected Handling. Boxes and their covers shall be capable of withstanding the handling to which they are likely to be subjected.

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