Tablas Nec

Chapter 4

NEC & NEMA Standards

1

This section lists excerpts from industry, national, and international standards. The excerpts are for illustration and educational purposes. There are often several related tables and information for other configurations and applications. In addition, the standards have added detail and information that applies to all these excerpts. Therefore, anyapplication should refer to the standard, rather than the excerpts.
Standard National Electrical Code (NEC) NFPA 70-2005 National Electrical Safety Code (NESC) IEEE C2-2002 Motors and Generators (MG1) NEMA MG1-2003 Organization National Fire Protection Association, Batterymarch Park, Quincy, MA Institute of Electrical & Electronics Engineers, New York, NewYork National Electrical ManufacturersAssociation Application Electrical installations in occupancies Electrical supply stations, overhead, and underground lines. Performance of motors and generators

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NEC 240.6(A)
15 125 600 20 150 700

Electric Power Systems
Standard Ampere Ratings for Fuses & Circuit Breakers
25 175 800 30 200 1000 35 225 1200 40 250 1600 Amperes 45 50 300 350 2000 2500 60 400 3000 70 450 4000 80 500 5000 906000 100 -

Durham

110 -

Chapter 4

NEC & NEMA Standards

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Table 310.16 Allowable Ampacities of Insulated Conductors Rated 0 Through 2000 Volts, 60°C Through 90°C (140°F Through 194°F), Not More Than Three Current-Carrying Conductors in Raceway, Cable, or Earth (Directly Buried), Based on Ambient Temperature of 30°C (86°F)
Temperature Rating of Conductor (See Table 310.13.) 60°C75°C 90°C 60°C 75°C 90°C (140°F) (167°F) (194°F) (140°F) (167°F) (194°F) Size AWG Types Types RHW, Types TBS, SA, SIS, Types Types RHW, Types TBS, SA, Size or kcmil TW, UF THHW, THW, FEP, FEPB, MI, RHH, TW, UF THHW, SIS, THHN, THHW, AWG or THWN, RHW-2, THHN, THHW, THW, THW-2, THWN-2, kcmil XHHW, USE, THW-2, THWN-2, THWN, RHH, RHW-2, USEZW USE-2, XHH, XHHW, XHHW, USE 2, XHH, XHHW, XHHW-2, ZW-2 XHHW-2,ZW-2 COPPER ALUMINUM OR COPPER-CLAD ALUM 18 — — 14 — — — — 16 — — 18 — — — — 14* 20 20 25 — — — — 12* 25 25 30 20 20 25 12* 10* 30 35 40 25 30 35 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 230260 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 485545 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. shown above by the appropriate factor shown below. Temp. (°C) (°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 0.91 0.940.96 0.91 0.94 0.96 87–95 36–40 0.82 0.88 0.91 0.82 0.88 0.91 96–104 41–45 0.71 0.82 0.87 0.71 0.82 0.87 105–113 46–50 0.58 0.75 0.82 0.58 0.75 0.82 114–122 51–55 0.41 0.67 0.76 0.41 0.67 0.76 123–131 56–60 — 0.58 0.71 — 0.58 0.71 132–140 61–70 — 0.33 0.58 — 0.33 0.58 141–158 71–80 — — 0.41 — — 0.41 159–176 * See 240.4(D).

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Table 310.15(B)(2)(a) Adjustment Factors for More Than ThreeCurrentCarrying Conductors in a Raceway or Cable
Number of CurrentCarrying Conductors 4–6 7–9 10–20 21–30 31–40 41 and above

Electric Power Systems

Durham

Percent of Values in Tables 310.16 through 310.19 as Adjusted for Ambient Temperature if Necessary 80 70 50 45 40 35

Table 310.15(B)(6) Conductor Types and Sizes for 120/240-Volt, 3-Wire, Single-Phase Dwelling Services and Feeders....