NEC Reference Tables
Essential NEC data tables used daily by electrical engineers and electricians.
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NEC 310.16 — Copper Conductor Ampacity
Allowable ampacities of insulated copper conductors rated up to 2000V, 60°C through 90°C. Not more than 3 current-carrying conductors in raceway, cable, or earth (directly buried), based on ambient temperature of 30°C.
| AWG / kcmil | 60°C TW, UF | 75°C THW, THWN | 90°C THHN, XHHW |
|---|---|---|---|
| 14 | 15A | 20A | 25A |
| 12 | 20A | 25A | 30A |
| 10 | 30A | 35A | 40A |
| 8 | 40A | 50A | 55A |
| 6 | 55A | 65A | 75A |
| 4 | 70A | 85A | 95A |
| 3 | 85A | 100A | 115A |
| 2 | 95A | 115A | 130A |
| 1 | 110A | 130A | 145A |
| 1/0 | 125A | 150A | 170A |
| 2/0 | 145A | 175A | 195A |
| 3/0 | 165A | 200A | 225A |
| 4/0 | 195A | 230A | 260A |
| 250 kcmil | 215A | 255A | 290A |
| 300 kcmil | 240A | 285A | 320A |
| 350 kcmil | 260A | 310A | 350A |
| 400 kcmil | 280A | 335A | 380A |
| 500 kcmil | 320A | 380A | 430A |
| 600 kcmil | 350A | 420A | 475A |
| 750 kcmil | 385A | 460A | 535A |
Source: NFPA 70, National Electrical Code®, Table 310.16. Refer to NEC for complete correction factors and notes.
NEC 310.16 — Aluminum Conductor Ampacity
Allowable ampacities of insulated aluminum or copper-clad aluminum conductors rated up to 2000V.
| AWG / kcmil | 60°C | 75°C | 90°C |
|---|---|---|---|
| 12 | 15A | 20A | 25A |
| 10 | 25A | 30A | 35A |
| 8 | 30A | 40A | 45A |
| 6 | 40A | 50A | 60A |
| 4 | 55A | 65A | 75A |
| 3 | 65A | 75A | 85A |
| 2 | 75A | 90A | 100A |
| 1 | 85A | 100A | 115A |
| 1/0 | 100A | 120A | 135A |
| 2/0 | 115A | 135A | 150A |
| 3/0 | 130A | 155A | 175A |
| 4/0 | 150A | 180A | 205A |
| 250 kcmil | 170A | 205A | 230A |
| 300 kcmil | 190A | 230A | 255A |
| 350 kcmil | 210A | 250A | 280A |
| 400 kcmil | 225A | 270A | 305A |
| 500 kcmil | 260A | 310A | 350A |
| 600 kcmil | 285A | 340A | 385A |
| 750 kcmil | 320A | 385A | 435A |
NEC Chapter 9, Table 4 — Conduit Internal Area (in²)
Internal cross-sectional areas for standard conduit trade sizes across EMT, IMC, RMC, and PVC Schedule 40.
| Trade Size | EMT | IMC | RMC | PVC Sch.40 |
|---|---|---|---|---|
| ½″ | 0.304 | 0.342 | 0.314 | 0.285 |
| ¾″ | 0.533 | 0.586 | 0.549 | 0.508 |
| 1″ | 0.864 | 0.959 | 0.887 | 0.832 |
| 1¼″ | 1.496 | 1.647 | 1.526 | 1.453 |
| 1½″ | 2.036 | 2.223 | 2.071 | 1.986 |
| 2″ | 3.356 | 3.63 | 3.408 | 3.291 |
| 2½″ | 5.858 | 6.277 | 5.958 | 5.453 |
| 3″ | 8.846 | 9.521 | 8.846 | 8.091 |
| 3½″ | 11.545 | — | 11.545 | 10.694 |
| 4″ | 14.753 | — | 14.753 | 13.631 |
Source: NFPA 70, Chapter 9, Table 4. Values in square inches (in²).
NEC 430.248 — Motor Full-Load Current (3φ, 460V)
Full-load current in amperes for three-phase AC motors at 460 volts. Use these values (not motor nameplate) for conductor sizing, overcurrent protection, and short-circuit calculations per NEC 430.6.
| HP | FLC (Amps) |
|---|---|
| ½ | 1.1 |
| ¾ | 1.6 |
| 1 | 2.1 |
| 1½ | 3 |
| 2 | 3.4 |
| 3 | 4.8 |
| 5 | 7.6 |
| 7½ | 11 |
| 10 | 14 |
| 15 | 21 |
| 20 | 27 |
| 25 | 34 |
| 30 | 40 |
| 40 | 52 |
| 50 | 65 |
| 60 | 77 |
| 75 | 96 |
| 100 | 124 |
| 125 | 156 |
| 150 | 180 |
| 200 | 240 |
NEC 240.6(A) — Standard Ampere Ratings
Standard ampere ratings for fuses and inverse time circuit breakers. The next standard size up rule applies per NEC 240.4(B).
NEC Table 250.66 — Grounding Electrode Conductor (GEC)
Minimum size of grounding electrode conductor based on the size of the largest ungrounded service-entrance conductor or equivalent area for parallel conductors.
| Service Conductor Size | GEC (Copper) | GEC (Aluminum) |
|---|---|---|
| 2 AWG or smaller | 8 AWG | 6 AWG |
| 1 AWG or 1/0 AWG | 6 AWG | 4 AWG |
| 2/0 or 3/0 AWG | 4 AWG | 2 AWG |
| Over 3/0 through 350 kcmil | 2 AWG | 1/0 AWG |
| Over 350 through 600 kcmil | 1/0 AWG | 3/0 AWG |
| Over 600 through 1100 kcmil | 2/0 AWG | 4/0 AWG |
| Over 1100 kcmil | 3/0 AWG | 250 kcmil |
NEC Table 250.122 — Equipment Grounding Conductor (EGC)
Minimum size of equipment grounding conductors based on the rating of the upstream overcurrent protective device (OCPD).
| OCPD Rating | EGC (Copper) | EGC (Aluminum) |
|---|---|---|
| 15A | 14 AWG | 12 AWG |
| 20A | 12 AWG | 10 AWG |
| 30A | 10 AWG | 8 AWG |
| 40A | 10 AWG | 8 AWG |
| 60A | 10 AWG | 8 AWG |
| 100A | 8 AWG | 6 AWG |
| 200A | 6 AWG | 4 AWG |
| 300A | 4 AWG | 2 AWG |
| 400A | 3 AWG | 1 AWG |
| 500A | 2 AWG | 1/0 AWG |
| 600A | 1 AWG | 2/0 AWG |
| 800A | 1/0 AWG | 3/0 AWG |
| 1000A | 2/0 AWG | 4/0 AWG |
| 1200A | 3/0 AWG | 250 kcmil |
| 1600A | 4/0 AWG | 350 kcmil |
| 2000A | 250 kcmil | 400 kcmil |
NEC Table 220.55 — Range Demand Factors (Column C)
Maximum demand for household electric ranges, wall-mounted ovens, and counter-mounted cooking units rated 8¾ kW to 12 kW. Column C values shown — adjust per Note 1 for ranges over 12 kW.
| Number of Units | Max Demand (Column C) |
|---|---|
| 1 | 8 kW |
| 2 | 11 kW |
| 3 | 14 kW |
| 4 | 17 kW |
| 5 | 20 kW |
| 6 | 21 kW |
| 7 | 22 kW |
| 8 | 23 kW |
| 9 | 24 kW |
| 10 | 25 kW |
| 11 | 26 kW |
| 12 | 27 kW |
| 13-14 | 28 kW |
| 15-16 | 29 kW |
| 17-20 | 30 kW |
| 21-25 | 34 kW |
| 26-30 | 35 kW |
NEC 310.15(C)(1) — Ambient Temperature Correction Factors
Multiply conductor ampacity by these factors when ambient temperature differs from 30°C (86°F). Factors less than 1.00 reduce ampacity; factors greater than 1.00 increase it.
| Ambient Temp | 60°C Factor | 75°C Factor | 90°C Factor |
|---|---|---|---|
| 10°C (50°F) | 1.29 | 1.2 | 1.15 |
| 15°C (59°F) | 1.22 | 1.15 | 1.12 |
| 20°C (68°F) | 1.15 | 1.11 | 1.08 |
| 25°C (77°F) | 1.08 | 1.05 | 1.04 |
| 30°C (86°F) | 1 | 1 | 1 |
| 35°C (95°F) | 0.91 | 0.94 | 0.96 |
| 40°C (104°F) | 0.82 | 0.88 | 0.91 |
| 45°C (113°F) | 0.71 | 0.82 | 0.87 |
| 50°C (122°F) | 0.58 | 0.75 | 0.82 |
| 55°C (131°F) | 0.41 | 0.67 | 0.76 |
| 60°C (140°F) | — | 0.58 | 0.71 |
Source: NFPA 70, Table 310.15(C)(1). Multiply ampacity from Table 310.16 by the correction factor for the ambient temperature.