Whenever we need to need how many amps a wire can handle, we turn to the NEC 310.16 table. The 310.16 table is basically an ampacity chart; it tells us what is the ampacity of copper and aluminum wires. The full name for this table is “Table 310.16 Ampacities of Insulated Conductors with Not More Than Three Current-Carrying Conductors in Raceway, Cable, or Earth (Directly Buried)”.
Before we check the full 210.16 table found in National Electrical Code (NEC), let’s first look at why it is structured in the way it is. Namely, the current carrying capability of a wire – ampacity – depends on three key factors:
- Size of the wire (expressed as AWG or kcmil). On the left side of the NEC 310.16 table (further on), we see different wire cross-sections (AWG or kcmil). The thicker the wire, the more amps it can carry. Wire ampacity increases with decreasing AWG number (Example: 12 AWG wire is thicker and can carry more amps than 14 AWG wire) and with increasing kcmil number (500 kcmil wire is thicker and can carry more current than 300 kcmil wire).
- Type of metal wire is made out of (copper or aluminum). As we will see in the NEC ampacity chart, copper wires can handle more amps than same-size aluminum wires. That’s because copper has a lower resistivity (1.72 × 10-8 Ohm×m at 68°F) than aluminum (2.65 × 10-8 Ohm×m at 68°F). That means that the conductivity of copper is higher than the conductivity of aluminum.
- Temperature. At higher temperatures, the conductivity of same-size same-type wire is higher. That’s why the NEC ampacity chart specifies the ampacity at 3 different temperatures; 60°C (140°F), 75°C (167°F), and 90°C (194°F). Temperatures also correspond to the type of wire (we will look at that and all the requirements for the NEC 310.16 table to hold true below the chart).
Understanding these three factors will help you understand and read the NEC ampacity chart. For clarity, we have divided this all-important 310.16 NEC table into two parts:
- 1st NEC 210.16 table includes copper wire ampacities from 18 AWG to 2000 kcmil for all 3 temperatures.
- 2nd NEC 210.16 table includes aluminum wire (or copper-clad aluminum wire) ampacities from 18 AWG to 2000 kcmil for all 3 temperatures.
Here is the 1st chart, followed by the 2nd chart.
NEC 210.16 Table For Copper Wire Ampacities (1st Chart)
| Copper Wire Size (AWG or kcmil): | Ampacity At 60°C (140°F): | Ampacity At 75°C (167°F): | Ampacity 90°C (194°F): |
| 18 AWG Copper Wire | – | – | 14 Amps |
| 16 AWG Copper Wire | – | – | 18 Amps |
| 14 AWG Copper Wire | 15 Amps | 20 Amps | 25 Amps |
| 12 AWG Copper Wire | 20 Amps | 25 Amps | 30 Amps |
| 10 AWG Copper Wire | 30 Amps | 35 Amps | 40 Amps |
| 8 AWG Copper Wire | 40 Amps | 50 Amps | 55 Amps |
| 6 AWG Copper Wire | 55 Amps | 65 Amps | 75 Amps |
| 4 AWG Copper Wire | 70 Amps | 85 Amps | 95 Amps |
| 3 AWG Copper Wire | 85 Amps | 100 Amps | 115 Amps |
| 2 AWG Copper Wire | 95 Amps | 115 Amps | 130 Amps |
| 1 AWG Copper Wire | 110 Amps | 130 Amps | 145 Amps |
| 1/0 or 0 AWG Copper Wire | 125 Amps | 150 Amps | 170 Amps |
| 2/0 or 00 AWG Copper Wire | 145 Amps | 175 Amps | 195 Amps |
| 3/0 or 000 AWG Copper Wire | 165 Amps | 200 Amps | 225 Amps |
| 4/0 or 0000 AWG Copper Wire | 195 Amps | 230 Amps | 260 Amps |
| 250 kcmil Copper Wire | 215 Amps | 255 Amps | 290 Amps |
| 300 kcmil Copper Wire | 240 Amps | 285 Amps | 320 Amps |
| 350 kcmil Copper Wire | 260 Amps | 310 Amps | 350 Amps |
| 400 kcmil Copper Wire | 280 Amps | 335 Amps | 380 Amps |
| 500 kcmil Copper Wire | 320 Amps | 380 Amps | 430 Amps |
| 600 kcmil Copper Wire | 350 Amps | 420 Amps | 475 Amps |
| 700 kcmil Copper Wire | 385 Amps | 460 Amps | 520 Amps |
| 750 kcmil Copper Wire | 400 Amps | 475 Amps | 535 Amps |
| 800 kcmil Copper Wire | 410 Amps | 490 Amps | 555 Amps |
| 900 kcmil Copper Wire | 435 Amps | 520 Amps | 585 Amps |
| 1000 kcmil Copper Wire | 455 Amps | 545 Amps | 615 Amps |
| 1250 kcmil Copper Wire | 495 Amps | 590 Amps | 665 Amps |
| 1500 kcmil Copper Wire | 525 Amps | 625 Amps | 705 Amps |
| 1750 kcmil Copper Wire | 545 Amps | 650 Amps | 735 Amps |
| 2000 kcmil Copper Wire | 555 Amps | 665 Amps | 750 Amps |
For most household uses, you would use the 2nd ampacity column (ampacity at 75°C (167°F)). Here is the breakdown of copper wire types of specific temperature:
- 1st ampacity column at 60°C (140°F) temperature is relevant for TW and UF copper wires.
- 2nd ampacity column at 75°C (167°F) temperature is relevant for RHW, THHW, THW, THWN, XHHW, USE, and ZW copper wires.
- 3rd ampacity column at 90°C (194°F) temperature is relevant for TBS, SA, SIS, FEP,FEPB, MI, RHH, RHW-2,THHN, THHW, THW-2,THWN-2, USE-2, XHH,XHHW, XHHW-2, and ZW-2 copper wires.
Let’s have a look at the 2nd part of the NEC 210.16 table that specifies the ampacities for aluminum wires:
NEC 210.16 Table For Aluminum Wire Ampacities (2nd Chart)
| Aluminum Wire Size (AWG or kcmil): | Ampacity At 60°C (140°F): | Ampacity At 75°C (167°F): | Ampacity 90°C (194°F): |
| 18 AWG Aluminum Wire | – | – | – |
| 16 AWG Aluminum Wire | – | – | – |
| 14 AWG Aluminum Wire | – | – | – |
| 12 AWG Aluminum Wire | 15 Amps | 20 Amps | 25 Amps |
| 10 AWG Aluminum Wire | 25 Amps | 30 Amps | 35 Amps |
| 8 AWG Aluminum Wire | 35 Amps | 40 Amps | 45 Amps |
| 6 AWG Aluminum Wire | 40 Amps | 50 Amps | 55 Amps |
| 4 AWG Aluminum Wire | 55 Amps | 65 Amps | 75 Amps |
| 3 AWG Aluminum Wire | 65 Amps | 75 Amps | 85 Amps |
| 2 AWG Aluminum Wire | 75 Amps | 90 Amps | 100 Amps |
| 1 AWG Aluminum Wire | 85 Amps | 100 Amps | 115 Amps |
| 1/0 or 0 AWG Aluminum Wire | 100 Amps | 120 Amps | 135 Amps |
| 2/0 or 00 AWG Aluminum Wire | 115 Amps | 135 Amps | 150 Amps |
| 3/0 or 000 AWG Aluminum Wire | 130 Amps | 155 Amps | 175 Amps |
| 4/0 or 0000 AWG Aluminum Wire | 150 Amps | 180 Amps | 205 Amps |
| 250 kcmil Aluminum Wire | 170 Amps | 205 Amps | 230 Amps |
| 300 kcmil Aluminum Wire | 195 Amps | 230 Amps | 260 Amps |
| 350 kcmil Aluminum Wire | 210 Amps | 250 Amps | 280 Amps |
| 400 kcmil Aluminum Wire | 225 Amps | 270 Amps | 305 Amps |
| 500 kcmil Aluminum Wire | 260 Amps | 310 Amps | 350 Amps |
| 600 kcmil Aluminum Wire | 285 Amps | 340 Amps | 385 Amps |
| 700 kcmil Aluminum Wire | 315 Amps | 375 Amps | 425 Amps |
| 750 kcmil Aluminum Wire | 320 Amps | 385 Amps | 435 Amps |
| 800 kcmil Aluminum Wire | 330 Amps | 395 Amps | 445 Amps |
| 900 kcmil Aluminum Wire | 355 Amps | 425 Amps | 480 Amps |
| 1000 kcmil Aluminum Wire | 375 Amps | 445 Amps | 500 Amps |
| 1250 kcmil Aluminum Wire | 405 Amps | 485 Amps | 545 Amps |
| 1500 kcmil Aluminum Wire | 435 Amps | 520 Amps | 585 Amps |
| 1750 kcmil Aluminum Wire | 455 Amps | 545 Amps | 615 Amps |
| 2000 kcmil Aluminum Wire | 470 Amps | 560 Amps | 630 Amps |
Here is the breakdown by aluminum wire type:
- 1st ampacity column at 60°C (140°F) temperature is relevant for TW and UF aluminum wires.
- 2nd ampacity column at 75°C (167°F) temperature is relevant for RHW, THHW, THW, THWN, XHHW, and USE aluminum wires.
- 3rd ampacity column at 90°C (194°F) temperature is relevant for TBS, SA, SIS, THHN, THHW, THW-2, THWN-2, RHH, RHW-2, USE-2, XHH, XHHW, XHHW-2, and ZW-2 aluminum wires.
Now, that we know all the copper and aluminum wire ampacities, let’s just cover the requirements and additional notes for the 210.16 table:
Requirements And Additional Notes
In order for the 210.16 to apply, these following 4 conditions need to be fulfilled:
- Conductors must be used in 2000 volts or below circuits.
- Conductor rating at the specified 3 temperatures must be observed.
- When installing wiring in your house, the presumed temperature is the ambient temperature of 30°C (86°F).
- The 210.16 table is applied to 1, 2, and 3 current-carrying conductors. If you have a 4 or 5 wire conductor, these ampacities do not apply.
With the complete NEC ampacity chart, we hope that now you have a good idea of how much current can any specified copper or aluminum wire handle. If you have any questions or suggestions, you can use the comment section below, and we will try to help you out.