NEC Table 310.18 — High-Temperature Conductor Ampacity
Conductors rated 150°C, 200°C and 250°C, not more than three in a raceway or cable, 40°C (104°F) ambient.
12 AWG copper in raceway carries 43 A at 150°C, 45 A at 200°C and 54 A as 250°C nickel-coated conductor, at 40°C ambient.
| Size | 150°C — Type Z (Cu) | 200°C — FEP, FEPB, PFA, SA (Cu) | 250°C — PFAH, TFE (nickel / nickel-coated Cu) | 150°C — Type Z (Al) |
|---|---|---|---|---|
| 14 AWG | 34 | 36 | 39 | — |
| 12 AWG | 43 | 45 | 54 | 30 |
| 10 AWG | 55 | 60 | 73 | 44 |
| 8 AWG | 76 | 83 | 93 | 57 |
| 6 AWG | 96 | 110 | 117 | 75 |
| 4 AWG | 120 | 125 | 148 | 94 |
| 3 AWG | 143 | 152 | 166 | 109 |
| 2 AWG | 160 | 171 | 191 | 124 |
| 1 AWG | 186 | 197 | 215 | 145 |
| 1/0 AWG | 215 | 229 | 244 | 169 |
| 2/0 AWG | 251 | 260 | 273 | 198 |
| 3/0 AWG | 288 | 297 | 308 | 227 |
| 4/0 AWG | 332 | 346 | 361 | 260 |
These tables cover special high-temperature conductors — fixture and appliance wiring, furnaces, kilns and industrial process equipment. They are based on a 40°C ambient, not 30°C, and the terminations must also be rated for the temperature; ordinary breakers and lugs are not. The 250°C column applies to nickel or nickel-coated copper conductors.
Frequently asked questions
What wire is rated for 200°C?
Types FEP, FEPB, PFA and SA are rated 200°C in the applications covered by the table. Type Z is rated 150°C and types PFAH and TFE 250°C.
Can I use these ampacities with a standard circuit breaker?
Not directly. Terminations on standard breakers are rated 60 or 75°C, so the conductor must be sized from Table 310.16 at the termination. High-temperature wire is normally used only for the hot section of the run.
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