Article 312 Cabinets, Cutout Boxes, and Meter Socket Enclosures
Exception: Nonmetallic enclosures shall be permitted to be installed without the airspace on a concrete, masonry, tile, or similar surface.
Informational Note: For protection against corrosion, see 300.6.
Exception No. 1: Cables with entirely nonmetallic sheaths shall be permitted to enter the top of a surface-mounted enclosure through one or more nonflexible raceways not less than 450 mm (18 in.) and not more than 3.0 m (10 ft) in length, provided all of the following conditions are met:
- Each cable is fastened within 300 mm (12 in.), measured along the sheath, of the outer end of the raceway.
- The raceway extends directly above the enclosure and does not penetrate a structural ceiling.
- A fitting is provided on each end of the raceway to protect the cable(s) from abrasion and the fittings remain accessible after installation.
- The raceway is sealed or plugged at the outer end using approved means so as to prevent access to the enclosure through the raceway.
- The cable sheath is continuous through the raceway and extends into the enclosure beyond the fitting not less than 6 mm (1/4 in.).
- The raceway is fastened at its outer end and at other points in accordance with the applicable article.
- Where installed as conduit or tubing, the cable fill does not exceed the amount that would be permitted for complete conduit or tubing systems by Table 1 of Chapter 9 of this Code and all applicable notes thereto. Note 2 to the tables in Chapter 9 does not apply to this condition.
Informational Note: See Table 1 in Chapter 9, including Note 9, for allowable cable fill in circular raceways. See 310.15(C)(1) for required ampacity reductions for multiple cables installed in a common raceway.
Table 312.6(A) Minimum Wire-Bending Space at Terminals and Minimum Width of Wiring Gutters
|Wire Size (AWG or kcmil)||Wires per Terminal|
|All Other Conductors||Compact Stranded AA-8000 Aluminum Alloy Conductors (see Note 2)||1||2||3||4||5|
1. Bending space at terminals shall be measured in a straight line from the end of the lug or wire connector (in the direction that the wire leaves the terminal) to the wall, barrier, or obstruction.
|2. This column shall be permitted to be used to determine the minimum wire—bending space for compact stranded aluminum conductors in sizes up to 1000 kcmil and manufactured using AA—8000 series electrical grade aluminum alloy conductor material in accordance with 310.3(B). The minimum width of the wire gutter space shall be determined using the all other conductors value in this table.|
Exception No. 1: Where the distance between the wall and its terminal is in accordance with Table 312.6(A), a conductor shall be permitted to enter or leave an enclosure through the wall opposite its terminal, provided the conductor enters or leaves the enclosure where the gutter joins an adjacent gutter that has a width that conforms to Table 312.6(B) for the conductor.
Exception No. 2: A conductor not larger than 350 kcmil shall be permitted to enter or leave an enclosure containing only a meter socket(s) through the wall opposite its terminal, provided the distance between the terminal and the opposite wall is not less than that specified in Table 312.6(A) and the terminal is a lay-in type or removable lug with integral mounting tang, where the terminal is either of the following:
- Directed toward the opening in the enclosure and within a 45-degree angle of directly facing the enclosure wall
- Directly facing the enclosure wall and offset not greater than 50 percent of the bending space specified in Table 312.6(A)
Table 312.6(B) Minimum Wire-Bending Space at Terminals
|Wire Size (AWG or kcmil)||Wires per Terminal|
|1||2||3||4 or More|
|All Other Conductors||Compact Stranded AA-8000 Aluminum Alloy Conductors (See Note 3.)||mm||in.||mm||in.||mm||in.||mm||in.|
1. Bending space at terminals shall be measured in a straight line from the end of the lug or wire connector in a direction perpendicular to the enclosure wall.
|2. For removable and lay-in wire terminals intended for only one wire, bending space shall be permitted to be reduced by the following number of millimeters (inches):|
|a12.7 mm (1/2 in.)|
|b25.4 mm (1 in.)|
|c38.1 mm (l1/2 in.)|
|d50.8 mm (2 in.)|
|e76.2 mm (3 in.)|
|3. This column shall be permitted to determine the required wire-bending space for compact stranded aluminum conductors in sizes up to 1000 kcmil and manufactured using AA-8000 series electrical grade aluminum alloy conductor material in accordance with 310.3(B).|
- The total of all conductors installed at any cross section of the wiring space does not exceed 40 percent of the crosssectional area of that space.
- The total area of all conductors, splices, and taps installed at any cross section of the wiring space does not exceed 75 percent of the cross-sectional area of that space.
- A warning label complying with 110.21(B) is applied to the enclosure that identifies the closest disconnecting means for any feed-through conductors.
(a) Conductors shall comply with 725.49.
(b) Conductors smaller than 18 AWG, but not smaller than 22 AWG for a single conductor and 26 AWG for a multiconductor cable, shall be permitted to be used where the conductors and cable assemblies meet all of the following conditions:
- Are enclosed within raceways or routed along one or more walls of the enclosure and secured at intervals that do not exceed 250 mm (10 in.)
- Are secured within 250 mm (10 in.) of terminations
- Are secured to prevent contact with current carrying components within the enclosure
- Are rated for the system voltage and not less than 600 volts
- Have a minimum insulation temperature rating of 90°C