Resolución 2535: adopta el Código Eléctrico Nacional, versión 1993. (Sustituye el Anejo A del Reglamento 4435)

(b) Equipment Grounding Conductors. Bare, covered, or insulated grounding conductors shall be permitted. Individually covered or insulated grounding conductors shall have a continuous outer finish that is either green, or green with one or more yellow stripes. ARTICLE 310 - CONDUCTORS FOR GENERAL WIRING 70-165 Exception No. 1: An insulated or covered conductor larger than No. 6 shall, at the time of installation, be permitted to be permanently identified as a grounding conductor at each end and at every point where the conductor is accessible. Identification shall be accomplished by one of the following means: a. Stripping the insulation or covering from the entire exposed length; b. Coloring the exposed insulation or covering green; or c. Marking the exposed insulation or covering with green colored tape or green colored adhesive labels. Exception No. 2: Where the conditions of maintenance and supervision assure that only qualified persons will service the installation, an insulated conductor in a multiconductor cable shall, at the time of installation, be permitted to be permanently identified as a grounding conductor at each end and at every point where the conductor is accessible by one of the following means: a. Stripping the insulation from the entire exposed length; b. Coloring the exposed insulation green; or c. Marking the exposed insulation with green colored tape or green colored adhesive labels. (c) Ungrounded Conductors. Conductors that are intended for use as ungrounded conductors, whether used as single conductors or in multiconductor cables, shall be finished to be clearly distinguishable from grounded and grounding conductors. Ungrounded conductors shall be distinguished by colors other than white, natural gray, or green; or by a combination of color plus distinguishing marking. Distinguishing markings shall also be in a color other than white, natural gray, or green, and shall consist of a stripe or stripes or a regularly spaced series of identical marks. Distinguishing markings shall not conflict in any manner with the surface markings required by Section 310-11(b)(1). Exception: As permitted by Section 200-7. 310-13. Conductor Constructions and Applications. Insulated conductors shall comply with the applicable provisions of one or more of the following: Tables 310-13, 310-61, 310-62, 310-63, and 310-64. These conductors shall be permitted for use in any of the wiring methods recognized in Chapter 3 and as specified in their respective tables. (FPN): Thermoplastic insulation may stiffen at temperatures colder than minus 10°C (plus 14°F), requiring that care be exercised during installation at such temperatures. Thermoplastic insulation may also be deformed at normal temperatures where subjected to pressure, requiring care be exercised during installation and at points of support. Thermoplastic insulation, where used on dc circuits in wet locations, may result in electroendosmosis between conductor and insulation. 310-14. Aluminum Conductor Material. Solid aluminum conductors No. 8, 10, and 12 shall be made of an AA-8000 series electrical grade aluminum alloy conductor material. Stranded aluminum conductors No. 8 through 1000 kcmil marked as Type XHHW, THW, THHW, THWN, THHN, service-entrance Type SE Style U and SE Style R shall be made of an AA-8000 series electrical grade aluminum alloy conductor material. Table 310-13. Conductor Application and Insulations Max. AWG Thickness 70-166 Trade Type Operating Application or of Outer Name Letter Temp. Provisions Insulation kcmil Insulation Mils Covering**** Fluorinated FEP 90° C Dry and damp locations. Fluorinated Ethylene or 194° F Ethylene 14-10 20 None Propylene FEPB 200° C Dry locations-special applica- Propylene 8-2 30 392° F tions. Fluorinated 14-8 14 Glass braid Ethylene Asbestos or Propylene 6-2 14 other suitable braid materal 18-16***** 23 Mineral Insulation MI 90° F Dry and wet locations. Magnesium 16-10 36 (Metal Sheathed) 194° F Oxide 9-4 50 Copper or 250° C For special application. 3-500 55 Alloy Steel 482° F Moisture-, Heat-, 60° C Machine tool wiring in wet lo- Flame- (A) (B) NATIONAL ELECTRICAL CODE and Oil-Resistant 140° F cations as permitted in NFPA Retardant, 22-12 30 15 (A) None Thermoplastic MTW++ 79. (See Article 670). Moisture-, 10 30 20 Machine tool wiring in dry lo- Heat-, and 8 45 30 (B) Nylon 90° C cations as permitted in NFPA Oil-Re- 6 60 30 jacket 194° F 79. (See Article 670.) sistant 4-2 60 40 or Thermo- 1-4/0 80 50 equivaplastic 213-500 95 60 lent 501-1000 110 70 Paper 85° C For underground service con- 185° F ductors, or by special permis- Paper Lead sheath sion. ****Some insulations do not require an outer covering. I *****For signaling circuits permitting 300-volt insulation. +Where environmental conditions require maximum conductor operating temperatures above 90°C. Insulation and outer coverings that meet the requirements of flame-retardant, limited-smoke and are so listed shall be permitted to be designated limited-smoke with the suffix /LS after the Code type designation. Table 310-13. (Continued) Perfluoro- PFA 90° C Dry and damp locations. Perfluoro- 14-10 20 alkoxy 194° F alkoxy 8-2 30 None 200° C Dry locations-special applica- 1-4/0 45 392° F tions.+ Perfluoro- PFAH 250° C Dry locations only. Only for Perfluoro- 14-10 20 alkoxy 482° F leads within apparatus or alkoxy 8-2 30 within raceways connected to 1-4/0 45 None apparatus. (Nickel or nickelcoated copper only.) Heat-Resistant RH 75° C Dry and damp locations. 14-12** 30 Moistureor Cross- 167° F 10 45 resistant, Linked Syn- 8-2 60 flamethetic Polymer 1-4/0 80 retardant, 213-500 95 non- Heat-Resistant RHH++ 90° C Dry and damp locations. Heat- 501-1000 110 metallic or Cross- 194° F Resistant 1001-2000 125 covering* Linked Synor Cross- For 601-2000 volts, thetic Polymer Linked see Table 310-62. Synthetic Polymer Moisture- and RHW+, 75° C Dry and wet locations. Moisture- 14-10 45 Moisture- Heat-Resistant +++ 167° F Where over 2000 volts insulaand Heat- 8-2 60 resistant, or Crosston, shall be ozone-resistant Resistant 1-4/0 80 flame- Linked Synor Cross- 213-500 95 retardant, ARTICLE 310 CONDUCTORS FOR GENERAL WIRING thetic Polymer Linked 501-1000 110 non- Synthetic 1001-2000 125 metallic Polymer For 601-2000 volts, covering* see Table 310-62. *Some rubber insulations do not require an outer covering. **For size Nos. 14-12, RHH shall be 45 mils thickness insulation. Where environmental conditions require maximum conductor operating temperatures above 90°C. ++Insulation and outer coverings that meet the requirements of flame-retardant, limited-smoke and are so listed shall be permitted to be designated limited-smoke with the suffix /LS after the Code type designation. ittListed wire types designated with the suffix "-2," such as RHW-2, shall be permitted to be used at a continuous 90°C-operating temperature, 70-167 I wet or dry. Table 310-13. (Continued) Max. AWG Thickness 70-168 Trade Type Operating Application or of Outer Name Letter Temp. Provisions Insulation kcmil Insulation Mils Covering**** 14-10 45 Moisture- Moisture- 8-2 60 Moisture- and resistant, and Heat- 1-4/0 80 flame- Heat-Resistant 90° C Resistant or 213-500 95 or Cross- RHW-2 retardant, 194° F Dry and wet locations. Cross-Linked 501-1000 110 nonmetallic Linked Syn- Synthetic 1001-2000 125 thetic Polymer covering* Polymer For 601-2000 volts, see Table 310-62. Silicone- SA 90° C Dry and damp locations. 14-10 45 Asbestos, Asbestos 194° F 8-2 60 glass, or 1-4/0 80 other 125° C For special application. Silicone Rubber 213-500 95 suitable 257° F. 501-1000 110 braid 1001-2000 125 material Synthetic SISTT 90° C Switchboard wiring only. Heat-Resistant 14-10 30 Heat-Resistant 194° F Cross-Linked 8 45 NATIONAL ELECTRICAL CODE None Synthetic 6-2 60 Polymer 1-4/0 80 Thermoplastic TA 90° C Switchboard wiring only. Thermoplastic Th'pl'. Asb. Flameand Asbestos 194° F and Asbestos 14-8 20 20 retardant, 6-2 30 25 nonmetallic 1-4/0 40 30 covering Thermoplastic TBS 90° C Switchboard wiring only. Thermoplastic 14-10 30 Flameand Fibrous 194° F 8 45 retardant, Outer Braid 6-2 60 nonmetallic 1-4/0 80 covering *Some rubber insulations do not require an outer covering. ****Some insulations do not require an outer covering. +Where environmental conditions require maximum conductor operating temperatures above 90°C. ++Insulation and outer coverings that meet the requirements of flame-retardant, limited-smoke and are so listed shall be permitted to be designated limited-smoke with the suffix /LS after the Code type designation. Table 310-13. (Continued) Extended TFE 250° C Dry locations only. Only for Extruded 14-10 20 Polytetra- 482° F leads within apparatus or Polytetra- 8-2 30 fluoroethylene within raceways connected fluoro- 1-4/0 45 None to apparatus, or as open ethylene wiring. (Nickel or nickelcoated copper only.) Heat-Resistant THHN++ 90° C Dry and damp locations. Flame- 14-12 15 Nylon Thermoplastic 194° F Retardant, 10 20 jacket or Heat- 8-6 30 equivalent Resistant 4-2 40 Thermo- 1-4/0 50 plastic 250-500 60 501-1000 70 Moisture- and THHW 75° C Wet location. Flame- 14-10 45 Heat-Resistant 167° F Retardant, 8-2 60 Thermoplastic 90° C Dry location. Moisture- 1-4/0 80 194° F and Heat- 213-500 95 None Resistant 501-1000 110 Thermoplastic Moisture- and THW 75° C Dry and wet locations. Flame- 14-10 45 ARTICLE 310 CONDUCTORS FOR GENERAL WIRING Heat-Resistant +++ 167° F Retardant, 8-2 60 Thermoplastic 90° C Special applications within Moisture- 1-4/0 80 194° F electric discharge lighting and Heat- 213-500 95 None equipment. Limited to 1000 Resistant 501-1000 110 open-circuit volts or less. Thermo- 1001-2000 125 (Size 14-8 only as permitted plastic in Section 410-31.) +Insulation and outer coverings that meet the requirements of flame-retardant, limited-smoke and are so listed shall be permitted to be designated limited-smoke with the suffix /LS after the Code type designation. +++Listed wire types designated with the suffix "-2," such as RHW-2 shall be permitted to be used at a continuous 90°C-operating temperature, 70-169 I wet or dry. Table 310-13. (Continued) Max. AWG Thickness Trade Type Operating Application or of Outer Name Letter Temp. Provisions Insulation kcmil Insulation Mils 70-170 Covering**** Flame- 14-12 15 Retardant, 10 20 Moisture- and Moisture- THWN 75° C 8-6 30 Nylon Heat-Resistant TT, +++ 167° F Dry and wet locations. and Heat- 4-2 40 jacket Thermoplastic Resistant 1-4/0 50 or equivalent Thermo- 250-500 60 plastic 501-1000 70 Flame- 14-10 30 Retardant, 8 45 Moisture- 60° C Moisture- 6-2 60 Resistant TWTT Dry and wet locations. Resistant 140° F 1-4/0 80 None Thermoplastic Thermo- 213-500 95 plastic 501-1000 110 1001-2000 125 Underground Feeder and 60° C Moisture- Branch-Circuit 140° F Resistant NATIONAL ELECTRICAL CODE Cable-Single Conductor. 14-10 60* Integral UF See Article 339. 8-2 (For Type UF 80* with 1-4/0 95* cable employing 75° C insulation Moisturemore than one 167° F** and Heatconductor, see Resistant Article 339.) *Includes integral jacket. **For ampacity limitation, see Section 339-5. Some insulations do not require an outer covering. ++Insulation and outer coverings that meet the requirements of flame-retardant, limited-smoke and are so listed shall be permitted to be designated limited-smoke with the suffix /LS after the Code type designation. IttListed wire types designated with the suffix "-2," such as RHW-2 shall be permitted to be used at a continuous 90°C-operating temperature, wet or dry. Table 310-13. (Continued) Underground Service- Moisture- Entrance 12-10 45 resistant Cable-Single 8-2 60 Heat- and non- Conductor. 75° C 1-4/0 80 USETTI See Article 338. Moisturemetallic (For Type USE 167° F 213-500 95*** Resistant cable employing 501-1000 110 covering more than one 125 [See Section 1001-2000 338-1(b).] conductor, see Article 338.) Heat-Resistant XHH ++ 90° C Dry and damp locations. Flame- 14-10 30 None Cross-Linked 194° F Retardant 8-2 45 Synthetic Cross- 1-4/0 55 Polymer Linked 213-500 65 Synthetic 501-1000 80 Polymer 1001-2000 95 Moisture- and 90° C Dry and damp locations. Flame- 14-10 30 Heat-Resistant 194° F Retardant 8-2 45 Cross-Linked XHHW Cross- 1-4/0 55 None Synthetic TT, +++ 75° C Wet locations. Linked 213-500 65 Polymer 167° F Synthetic 501-1000 80 ARTICLE 310 - CONDUCTORS FOR GENERAL WIRING Polymer 1001-2000 95 ***Insulation thickness shall be permitted to be 80 mils for listed Type USE conductors that have been subjected to special investigations. The nonmetallic covering over individual rubber-covered conductors of aluminum-sheathed cable and of lead-sheathed or multiconductor cable shall not be required to be flame-retardant. For Type MC cable, see Section 334-20. For nonmetallic-sheathed cable, see Section 336-25. For Type UF cable, see Section 339-1. ++Insulation and outer coverings that meet the requirements of flame-retardant, limited-smoke and are so listed shall be permitted to be designated limited-smoke with the suffix /LS after the Code type designation. +++Listed wire types designated with the suffix "-2," such as RHW-2, shall be permitted to be used at a continuous 90°C-operating temperature, wet or dry. 70-171 70-172 Table 310-13. (Continued) Max. AWG Thickness Trade Type Operating Application or of Outer Name Letter Temp. Provisions Insulation kcmil Insulation Mils Covering*** Moisture- and 90° C Dry and wet locations. Flame- 14-10 30 Heat-Resistant 194° F Retardant 8-2 45 Cross-Linked XHHW-2 Cross-Linked 1-4/0 55 Synthetic 213-500 None Synthetic 65 Polymer Polymer 501-1000 80 1001-2000 95 Modified Z 90° C Dry and damp locations. Modified 14-12 15 Ethylene 194° F Ethylene 10 20 Tetrafluoro- 150° C Dry locations-special appli- Tetrafluoro- 8-4 25 None ethylene 302° F cations. ethylene 3-1 35 1/0-4/0 45 Modified ZWITT 75° C Wet locations. Modified 14-10 30 NATIONAL ELECTRICAL CODE Ethylene 167° F Ethylene 8-2 45 Tetrafluoro- 90° C Dry and damp locations. Tetrafluoroethylene 194° F None ethylene 150° C Dry locations-special appli- 302° F cations. ****Some insulations do not require an outer covering. Where environmental conditions require maximum conductor operating temperatures above 90°C. +++Listed wire types designated with the suffix "-2," such as RHW-2 , shall be permitted to be used at a continuous 90°C-operating temperature, wet I or dry. ARTICLE 310 - CONDUCTORS FOR GENERAL WIRING 70-173 310-15. Ampacities. Ampacities for conductors shall be permitted to be determined by (a) or (b) below. (FPN): Ampacities provided by this section do not take voltage drop into consideration. Conductors of circuits as defined in Article 100, sized to prevent a voltage drop exceeding 5 percent, will provide reasonable efficiency of operation. (a) General. Ampacities for conductors rated 0 to 2000 volts shall be as specified in the Allowable Ampacity Tables 310-16 through 310-19 and their accompanying notes. Ampacities for solid dielectric insulated conductors rated 2001 through 35,000 volts shall be as specified in Tables 310-67 through 310-84 and their accompanying notes. (FPN): Tables 310-16 through 310-19 are application tables that are for use in determining conductor sizes on loads calculated in accordance with Article 220. Allowable ampacities result from consideration of one or more of the following: 1. Temperature compatibility with connected equipment, especially at the connection points. 2. Coordination with circuit and system overcurrent protection. 3. Compliance with the requirements of product listings or certifications. See Section 110-3(b). 4. Preservation of the safety benefits of established industry practices and standardized procedures. (b) Engineering Supervision. Under engineering supervision, conductor ampacities shall be permitted to be calculated by means of the following general formula: I = TC - (TA + DELTA TD) RDC (1 + YC)RCA Where: TC = Conductor temperature in degrees C. TA = Ambient temperature in degrees C. DELTA TD = Dielectric loss temperature rise. RDC = DC resistance of conductor at temperature TC. YC = Component ac resistance resulting from skin effect and proximity effect. RCA = Effective thermal resistance between conductor and surrounding ambient. (FPN): See Appendix B for examples of formula applications. (c) Selection of Ampacity. Where more than one calculated or tabulated ampacity could apply for a given circuit length, the lowest value shall be used. Exception: Where two different ampacities apply to adjacent portions. of a circuit, the higher ampacity shall be permitted to be used beyond the point of transition, a distance equal to 10 feet (3.05 m) or 10 percent of the circuit length figured at the higher ampacity, whichever is less. (FPN): See Section 110-14(c) for conductor temperature limitations due to termination provisions. (d) Electrical Ducts. Electrical ducts as used in Article 310 shall include any of the electrical conduits recognized in Chapter 3 as suitable for use underground; and other raceways round in cross section, listed for underground use; embedded in earth or concrete. 70-174 NATIONAL ELECTRICAL CODE Table 310-16. Allowable Ampacities of Insulated Conductors Rated 0-2000 Volts, 60° to 90°C (140° to 194°F) Not More Than Three Conductors in Raceway or Cable or Earth (Directly Buried), Based on Ambient Temperature of 30°C (86°F) Size Temperature Rating of Conductor. See Table 310-13. Size 60°C 75°C 90°C 60°C 75°C 90°C (140°F) (167°F) (194°F) (140°F) (167°F) (194°F) TYPES TYPES TYPES TYPES TYPES TYPES TWT, FEPWt, TA, TBS, SA TWT, RHt, RHWt, TA, TBS, UFt RHt, RHWt, SIS, FEPT, UFt THHWT, SA, SIS, THHWT, FEPBT, MI THWT, THHNt, AWG THWT, RHHT, RHW-2, THWNT, THHW+, AWG kcmil THWNT, THHNT, THHW+, XHHWT, THW-2, THWN-2, kcmil XHHW+ THW-2, THWN-2, USET RHHt, RHW-2 USEt, ZWT USE-2, XHH, USE-2 XHHWt XHH, XHHW XHHW-2, ZW-2 XHHW-2, ZW-2 COPPER ALUMINUM OR COPPER-CLAD ALUMINUM 18 14 16 18 14 20t 20+ 25+ 12 25f 25+ 30+ 20t 20+ 25t 12 10 30 35t 40+ 25 30f 35t 10 8 40 50 55 30 40 45 8 6 55 65 75 40 50 60 6 4 70 85 95 55 65 75 4 3 85 100 110 65 75 85 3 2 95 115 130 75 90 100 2 1 110 130 150 85 100 115 1 1/0 125 150 170 100 120 135 1/0 2/0 145 175 195 115 135 150 2/0 3/0 165 200 225 130 155 175 3/0 4/0 195 230 260 150 180 205 4/0 250 215 255 290 170 205 230 250 300 240 285 320 190 230 255 300 350 260 310 350 210 250 280 350 400 280 335 380 225 270 305 400 500 320 380 430 260 310 350 500 600 355 420 475 285 340 385 600 700 385 460 520 310 375 420 700 750 400 475 535 320 385 435 750 800 410 490 555 330 395 450 800 900 435 520 585 355 425 480 900 1000 455 545 615 375 445 500 1000 1250 495 590 665 405 485 545 1250 1500 520 625 705 435 520 585 1500 1750 545 650 735 455 545 615 1750 2000 560 665 750 470 560 630 2000 CORRECTION FACTORS Ambient For ambient temperatures other than 30°C (86°F), multiply the allowable ampacities Ambient Temp. °C shown above by the appropriate factor shown below. Temp. °F 21-25 1.08 1.05 1.04 1.08 1.05 1.04 70-77 26-30 1.00 1.00 1.00 1.00 1.00 1.00 78-86 31-35 .91 .94 .96 .91 .94 .96 87-95 36-40 .82 .88 .91 .82 .88 .91 96-104 41-45 .71 .82 .87 .71 .82 .87 105-113 46-50 .58 .75 .82 .58 .75 .82 114-122 51-55 .41 .67 .76 .41 .67 .76 123-131 56-60 .58 .71 .58 .71 132-140 61-70 .33 .58 .33 .58 141-158 71-80 .41 .41 159-176 Unless otherwise specifically permitted elsewhere in this Code, the overcurrent protection for conductor types marked with an obelisk (f) shall not exceed 15 amperes for No. 14, 20 amperes for No. 12, and 30 amperes for No. 10 copper; or 15 amperes for No. 12 and 25 amperes for No. 10 aluminum and copperclad aluminum after any correction factors for ambient temperature and number of conductors have been applied. ARTICLE 310 - CONDUCTORS FOR GENERAL WIRING 70-175 Table 310-17. Allowable Ampacities of Single Insulated Conductors, Rated 0 through 2000 Volts, In Free Air Based on Ambient Air Temperature of 30°C (86°F) Size Temperature Rating of Conductor. See Table 310-13. Size 60°C 75°C 90°C 60°C 75°C 90°C (140°F) (167°F) (194°F) (140°F) (167°F) (194°F) TYPES TYPES TYPES TYPES TYPES TYPES TWT, FEPWt, TA, TBS, SA TWt, RHt, RHWt, TA, TBS, UFt RHt, RHWt, SIS, FEPt, UFT THHW+, SA, SIS, THHWT, FEPBt, MI, THWT, THHNT, AWG THWT, RHHt, RHW-2, THWNT, THHWT, AWG kcmil THWNT, THHNT, THHW+, XHHW+ THW-2, THWN-2, kcmil XHHW+ THW-2, THWN-2, RHHT, RHW-2, ZWt USE-2, XHH, USE-2, XHHWt, XHH, XHHWT, XHHW-2, ZW-2 XHHW-2, ZW-2 COPPER ALUMINUM OR COPPER-CLAD ALUMINUM 18 18 16 24 14 25t 30+ 35t 12 30+ 35t 40t 25t 30t 35f 12 10 40f 50t 55f 35f 40f 40f 10 8 60 70 80 45 55 60 8 6 80 95 105 60 75 80 6 4 105 125 140 80 100 110 4 3 120 145 165 95 115 130 3 2 140 170 190 110 135 150 2 1 165 195 220 130 155 175 1 1/0 195 230 260 150 180 205 1/0 2/0 225 265 300 175 210 235 2/0 3/0 260 310 350 200 240 275 3/0 4/0 300 360 405 235 280 315 4/0 250 340 405 455 265 315 355 250 300 375 445 505 290 350 395 300 350 420 505 570 330 395 445 350 400 455 545 615 355 425 480 400 500 515 620 700 405 485 545 500 600 575 690 780 455 540 615 600 700 630 755 855 500 595 675 700 750 655 785 885 515 620 700 750 800 680 815 920 535 645 725 800 900 730 870 985 580 700 785 900 1000 780 935 1055 625 750 845 1000 1250 890 1065 1200 710 855 960 1250 1500 980 1175 1325 795 950 1075 1500 1750 1070 1280 1445 875 1050 1185 1750 2000 1155 1385 1560 960 1150 1335 2000 CORRECTION FACTORS Ambient For ambient temperatures other than 30°C (86°F), multiply the allowable ampacities Ambient Temp. °C shown above by the appropriate factor shown below. Temp. °F 21-25 1.08 1.05 1.04 1.08 1.05 1.04 70-77 26-30 1.00 1.00 1.00 1.00 1.00 1.00 78-86 31-35 .91 .94 .96 .91 .94 .96 87-95 36-40 .82 .88 .91 .82 .88 .91 96-104 41-45 .71 .82 .87 .71 .82 .87 105-113 46-50 .58 .75 .82 .58 .75 .82 114-122 51-55 .41 .67 .76 .41 .67 .76 123-131 56-60 .58 .71 .58 .71 132-140 61-70 .33 .58 .33 .58 141-158 71-80 .41 .41 159-176 *Unless otherwise specifically permitted elsewhere in this Code, the overcurrent protection for conductor types marked with an obelisk (f) shall not exceed 15 amperes for No. 14, 20 amperes for No. 12, and 30 amperes for No. 10 copper; or 15 amperes for No. 12 and 25 amperes for No. 10 aluminum and copperclad aluminum. 70-176 NATIONAL ELECTRICAL CODE Table 310-18. Allowable Ampacities of Three Single Insulated Conductors Rated 0 through 2000 Volts, 150° to 250°C (302° to 482°F), in Raceway or Cable Based on Ambient Air Temperature of 40°C (104°F) Size Temperature Rating of Conductor. See Table 310-13. Size 150°C 200°C 250°C 150°C (302°F) (392°F) (482°F) (302°F) TYPES FEP, TYPES AWG TYPE FEPB, PFAH, TYPE AWG kcmil Z PFA TFE Z kcmil NICKEL OR ALUMINUM NICKEL- OR COPPER- COATED CLAD COPPER COPPER ALUMINUM 14 34 36 39 14 12 43 45 54 30 12 10 55 60 73 44 10 8 76 83 93 57 8 6 96 110 117 75 6 4 120 125 148 94 4 3 143 152 166 109 3 2 160 171 191 124 2 1 186 197 215 145 1 1/0 215 229 244 169 1/0 2/0 251 260 273 198 2/0 3/0 288 297 308 227 3/0 4/0 332 346 361 260 4/0 250 250 300 300 350 350 400 400 500 500 600 600 700 700 750 750 800 800 1000 1000 1500 1500 2000 2000 CORRECTION FACTORS Ambient For ambient temperatures other than 40°C (104°F), multiply the allowable ampaci- Ambient Temp. °C ties shown above by the appropriate factor shown below. Temp. °F 41-50 .95 .97 .98 .95 105-122 51-60 .90 .94 .95 .90 123-140 61-70 .85 .90 .93 .85 141-158 71-80 .80 .87 .90 .80 159-176 81-90 .74 .83 .87 .74 177-194 91-100 .67 .79 .85 .67 195-212 101-120 .52 .71 .79 .52 213-248 121-140 .30 .61 .72 .30 249-284 141-160 .50 .65 285-320 161-180 .35 .58 321-356 181-200 .49 357-392 201-225 .35 393-437 ARTICLE 310 - CONDUCTORS FOR GENERAL WIRING 70-177 Table 310-19. Allowable Ampacities for Single Insulated Conductors Rated 0 through 2000 Volts, 150° to 250°C (302° to 482°F), in Free Air Based on Ambient Air Temperature of 40°C (104°F) Size Temperature Rating of Conductor. See Table 310-13. Size 150°C 200°C 250°C 150°C (302°F) (392°F) Bare (482°F) (302°F) Bare or or AWG AWG TYPES covered covered kcmil kcmil FEP, conduc- TYPES conduc- TYPE FEPB, tors PFAH, TYPE tors Z PFA TFE Z NICKEL OR NICKEL- ALUMINUM COATED OR COPPER- COPPER COPPER CLAD ALUMINUM 14 46 54 30 59 25 14 12 60 68 35 78 47 30 12 10 80 90 50 107 63 35 10 8 106 124 70 142 83 55 8 6 155 165 95 205 112 75 6 4 190 220 125 278 148 100 4 3 214 252 150 327 170 120 3 2 255 293 175 381 198 135 2 1 293 344 200 440 228 160 1 1/0 339 399 235 532 263 185 1/0 2/0 390 467 275 591 305 215 2/0 3/0 451 546 320 708 351 250 3/0 4/0 529 629 370 830 411 285 4/0 250 415 325 250 300 460 360 300 350 520 405 350 400 560 435 400 500 635 495 500 600 710 560 600 700 780 615 700 750 805 635 750 800 835 660 800 900 865 715 900 1000 895 770 1000 1500 1205 980 1500 2000 1420 1215 2000 CORRECTION FACTORS Ambient For ambient temperatures other than 40°C (104°F), multiply the allowable ampacities Ambient Temp. °C shown above by the appropriate factor shown below. Temp. °F 41-50 .95 .97 .98 .95 105-122 51-60 .90 .94 .95 .90 123-140 61-70 .85 .90 .93 .85 141-158 71-80 .80 .87 .90 .80 159-176 81-90 .74 .83 .87 .74 177-194 91-100 .67 .79 .85 .67 195-212 101-120 .52 .71 .79 .52 213-248 121-140 .30 .61 .72 .30 249-284 141-160 .50 .65 285-320 161-180 .35 .58 321-356 181-200 .49 357-392 201-225 .35 393-437 70-178 NATIONAL ELECTRICAL CODE Notes to Ampacity Tables of 0 to 2000 Volts 1. Explanation of Tables. For explanation of type letters and for recognized size of conductors for the various conductor insulations, see Section 310-13. For installation requirements, see Sections 310-1 through 310-10 and the various articles of this Code. For flexible cords, see Tables 400-4, 400-5(A), and 400-5(B). 3. 120/240 Volts, 3-Wire, Single-Phase Dwelling Services and Feeders. For dwelling units, conductors, as listed below, shall be permitted to be utilized as 120/240-volt, 3-wire, single-phase service-entrance conductors, service lateral conductors, and feeder conductors that supply the total load to a dwelling unit and installed in raceway or cable with or without an equipment grounding conductor. The grounded conductor shall be permitted to be not more than two AWG sizes smaller than the ungrounded conductors for application of this note, provided the requirements of Sections 215-2, 220-22, and 230-42 are met. Conductor Types and Sizes RH-RHH-RHW-THHW-THW-THWN-THHN-XHHW-USE Aluminum or Copper Copper-Clad AL Rating in Amps AWG AWG 4 2 100 3 1 110 2 1/0 125 1 2/0 150 1/0 3/0 175 2/0 4/0 200 3/0 250 kcmil 225 4/0 300 kcmil 250 250 kcmil 350 kcmil 300 350 kcmil 500 kcmil 350 400 kcmil 600 kcmil 400 5. Bare Conductors. Where bare conductors are used with insulated conductors, their allowable ampacities shall be limited to those permitted for the adjacent insulated conductors. 6. Mineral-Insulated, Metal-Sheathed Cable. The temperature limitation on which the ampacities of mineral-insulated, metal-sheathed cable are based is determined by the insulating materials used in the end seal. Termination fittings incorporating unimpregnated, organic, insulating materials are limited to 90°C (194°F) operation. 7. Type MTW Machine Tool Wire. (FPN): For the allowable ampacities of Type MTW wire, see Table 13-5(a) in the Electrical Standard for Industrial Machinery, NFPA 79-1991. ARTICLE 310 - CONDUCTORS FOR GENERAL WIRING 70-179 8. Adjustment Factors. (a) More than Three Current-Carrying Conductors in a Raceway or Cable. Where the number of current-carrying conductors in a raceway or cable exceeds three, the allowable ampacities shall be reduced as shown in the following table: Percent of Values in Number of Tables as Adjusted for Current-Carrying Ambient Temperature Conductors if Necessary 4 through 6 80 7 through 9 70 10 through 20 50 21 through 30 45 31 through 40 40 41 and above 35 Where single conductors or multiconductor cables are stacked or bundled longer than 24 inches (610 mm) without maintaining spacing and are not installed in raceways, the allowable ampacity of each conductor shall be reduced as shown in the above table. Exception No. 1: Where conductors of different systems, as provided in