|ALLOWABLE WIRING METHOD||DESIGNATED ABBREVIATION|
|Electrical metallic tubing||EMT|
|Electrical nonmetallic tubing||ENT|
|Flexible metal conduit||FMC|
|Intermediate metal conduit||IMC|
|Liquidtight flexible conduit||LFC|
|Nonmetallic sheathed cable||NM|
|Rigid nonmetallic conduit||RNC|
|Rigid metallic conduit||RMC|
|Service entrance cable||SE|
|Underground feeder cable||UF|
|Underground service cable||USE|
(application allowed where marked with an "A")
|Inside a building||A||A||A||A||A||A||A||A||A||A||A||—|
|Wet locations exposed to sunlight||—||A||Ah||—||A||A||A||—||—||A||Ae||Ae|
|Embedded in noncinder concrete in dry
|In noncinder concrete in contact with grade||—||Af||A||—||Af||Aj||—||—||—||—||—||—|
|Embedded in plaster not exposed to dampness||A||A||A||A||A||A||A||—||—||A||A||—|
|Embedded in masonry||—||A||A||—||Af||A||A||—||—||—||—||—|
|In masonry voids and cells exposed to
dampness or below grade line
|Fished in masonry voids||A||—||—||A||—||A||A||A||—||A||A||—|
|In masonry voids and cells not exposed to
|Run exposed and subject to physical damage||—||—||—||—||Ag||—||—||—||—||—||—||—|
|For direct burial||—||Af||—||—||Af||A||Af||—||—||—||A||A|
- Liquid-tight flexible nonmetallic conduit without integral reinforcement within the conduit wall shall not exceed 6 feet in length.
- The grounded conductor shall be insulated except where used to supply other buildings on the same premises. Type USE cable shall not be used inside buildings.
- The grounded conductor shall be insulated.
- Conductors shall be a type approved for wet locations and the installation shall prevent water from entering other raceways.
- Shall be listed as "Sunlight Resistant."
- Metal raceways shall be protected from corrosion and approved for the application. Aluminum RMC requires approved supplementary corrosion protection.
- RNC shall be Schedule 80.
- Shall be listed as "Sunlight Resistant" where exposed to the direct rays of the sun.
- Conduit shall not exceed 6 feet in length.
- Liquid-tight flexible nonmetallic conduit is permitted to be encased in concrete where listed for direct burial and only straight connectors listed for use with LFNC are used.
- In wet locations under any of the following conditions:
- The metallic covering is impervious to moisture.
- A lead sheath or moisture-impervious jacket is provided under the metal covering.
- The insulated conductors under the metallic covering are listed for use in wet locations and a corrosion-resistant jacket is provided over the metallic sheath.
(Requirement applicable only to wiring methods marked "A" )
|Where run parallel with the framing member or furring strip, the wiring shall be not less than 11/4 inches from the edge of a furring strip or a framing member such as a joist, rafter or stud or shall be physically protected.||A||—||A||A||A||—||A||—||—|
|Bored holes in framing members for wiring shall be located not less than 11/4 inches from the edge of the framing member or shall be protected with a minimum 0.0625-inch steel plate or sleeve, a listed steel plate or other physical protection.||Ak||—||Ak||Ak||Ak||—||Ak||—||—|
|Where installed in grooves, to be covered by wallboard, siding, paneling, carpeting, or similar finish, wiring methods shall be protected by 0.0625-inch-thick steel plate, sleeve, or equivalent, a listed steel plate or by not less than 11/4-inch free space for the full length of the groove in which the cable or raceway is installed.||A||—||A||A||A||—||A||A||A|
|Securely fastened bushings or grommets shall be provided to protect wiring run through openings in metal framing members.||—||—||Aj||—||Aj||—||Aj||—||—|
|The maximum number of 90-degree bends shall not exceed four between junction boxes.||—||A||A||A||—||A||—||—||—|
|Bushings shall be provided where entering a box, fitting or enclosure unless the box or fitting is designed to afford equivalent protection.||A||A||A||A||—||A||—||A||—|
|Ends of raceways shall be reamed to remove rough edges.||—||A||A||A||—||A||—||A||—|
|Maximum allowable on center support spacing for the wiring method in feet.||4.5b, c||10l||3b||4.5b||4.5i||3d,l||2.5e||—||2.5e|
|Maximum support distance in inches from box or other terminations.||12b, f||36||36||12b,g||12h,i||36||12||—||12|
- Installed in accordance with listing requirements.
- Supports not required in accessible ceiling spaces between light fixtures where lengths do not exceed 6 feet.
- Six feet for MC cable.
- Five feet for trade sizes greater than 1 inch.
- Two and one-half feet where used for service or outdoor feeder and 4.5 feet where used for branch circuit or indoor feeder.
- Twenty-four inches where flexibility is necessary.
- Thirty-six inches where flexibility is necessary.
- Within 8 inches of boxes without cable clamps.
- Flat cables shall not be stapled on edge.
- Bushings and grommets shall remain in place and shall be listed for the purpose of cable protection.
- See Sections R502.8 and R802.7 for additional limitations on the location of bored holes in horizontal framing members.
- Where oversized, concentric or eccentric knockouts are not encountered, a raceway not greater than 18 inches in length shall not require support where it is a continuous length without couplings. Such raceways shall terminate at an outlet box, junction box, device box, cabinet, or other termination at each end of the raceway.
For types NM and SE cable, bends shall be so made, and other handling shall be such that the cable will not be damaged and the radius of the curve of the inner edge of any bend shall be not less than five times the diameter of the cable.
|LOCATION OF WIRING
METHOD OR CIRCUIT
|TYPE OF WIRING METHOD OR CIRCUIT|
Direct burial cables or conductors
Rigid metal conduit or intermediate metal conduit
Nonmetallic raceways listed for direct burial without concrete encasement or other approved raceways
Residential branch circuits rated 120 volts or less with GFCI protection and maximum overcurrent protection of 20 amperes
Circuits for control of irrigation and landscape lighting limited to not more than 30 volts and installed with type UF or in other identified cable or raceway
|All locations not specified below||24||6||18||12||6|
|In trench below 2-inch-thick concrete or equivalent||18||6||12||6||6|
|Under a building||0 (In raceway only)||0||0||0 (In raceway only)||0 (In raceway only)|
|Under minimum of 4-inch- thick concrete exterior slab with no vehicular traffic and the slab extending not less than 6 inches beyond the underground installation||18||4||4||6 (Direct burial)
4 (In raceway)
|6 (Direct burial)
4 (In raceway)
|Under streets, highways, roads, alleys, driveways and parking lots||24||24||24||24||24|
|One- and two-family dwelling driveways and outdoor parking areas, and used only for dwelling-related purposes||18||18||18||12||18|
|In solid rock where covered by minimum of 2 inches concrete extending down to rock||2 (In raceway only)||2||2||2 (In raceway only)||2 (In raceway only)|
- Raceways approved for burial only where encased concrete shall require concrete envelope not less than 2 inches thick.
- Lesser depths shall be permitted where cables and conductors rise for terminations or splices or where access is otherwise required.
- Where one of the wiring method types listed in columns 1 to 3 is combined with one of the circuit types in columns 4 and 5, the shallower depth of burial shall be permitted.
- Where solid rock prevents compliance with the cover depths specified in this table, the wiring shall be installed in metal or nonmetallic raceway permitted for direct burial. The raceways shall be covered by a minimum of 2 inches of concrete extending down to the rock.
- Cover is defined as the shortest distance in inches (millimeters) measured between a point on the top surface of any direct-buried conductor, cable, conduit or other raceway and the top surface of finished grade, concrete, or similar cover.
All conductors of the same circuit and, where present, the grounded conductor and all equipment grounding conductors shall be installed in the same raceway or shall be installed in close proximity in the same trench.
Exception: Where conductors are installed in parallel in raceways, each raceway shall contain all conductors of the same circuit including grounding conductors.