(a) Each conductor must be insulated, stranded copper.
(b) Except for intermittent surges each conductor must not carry a current greater than that specified in Table 5 for the conductor's gauge and temperature rating.
(c) For conductors in engine spaces, amperages must be corrected by the appropriate correction factor in note 1 of Table 5.
(d) Each conductor in a multiconductor sheath must be at least a No. 18 AWG conductor.
(e) Each conductor installed separately must be at least a No. 16 AWG conductor.
(f) Each No. 18 AWG conductor in a multiconductor sheath may not extend out of the sheath more than 30 inches.
(g) This section does not apply to communications systems; electronic navigation equipment; electronic circuits having a current flow of less than one ampere; conductors which are totally inside an equipment housing; resistance conductors that control circuit amperage; high voltage secondary conductors and terminations that are in ignition systems; pigtails of less than seven inches of exposed length and cranking motor conductors.
Table 5 - Allowable Amperage of Conductors
| Conductor size (AWG) | Temperature rating of conductor insulation | ||||||
|---|---|---|---|---|---|---|---|
| 60 °C (140 °F) | 75 °C (167 °F) | 80 °C (176 °F) | 90 °C (194 °F) | 105 °C (221 °F) | 125 °C (257 °F) | 200 °C (392 °F) | |
| 18 | 10 | 10 | 15 | 20 | 20 | 25 | 25 |
| 16 | 15 | 15 | 20 | 25 | 25 | 30 | 35 |
| 14 | 20 | 20 | 25 | 30 | 35 | 40 | 45 |
| 12 | 25 | 25 | 35 | 40 | 45 | 50 | 55 |
| 10 | 40 | 40 | 50 | 55 | 60 | 70 | 70 |
| 8 | 55 | 65 | 70 | 70 | 80 | 90 | 100 |
| 6 | 80 | 95 | 100 | 100 | 120 | 125 | 135 |
| 4 | 105 | 125 | 130 | 135 | 160 | 170 | 180 |
| 3 | 120 | 145 | 150 | 155 | 180 | 195 | 210 |
| 2 | 140 | 170 | 175 | 180 | 210 | 225 | 240 |
| 1 | 165 | 195 | 210 | 210 | 245 | 265 | 280 |
| 0 | 195 | 230 | 245 | 245 | 285 | 305 | 325 |
| 00 | 225 | 265 | 285 | 285 | 330 | 355 | 370 |
| 000 | 260 | 310 | 330 | 330 | 385 | 410 | 430 |
| 0000 | 300 | 360 | 385 | 385 | 445 | 475 | 510 |
| NOTES | |||||||
| 1. See the following table: | 60 °C | 75 °C | 80 °C | 90 °C | 105 °C | 125 °C | 200 °C |
| (140 °F) | (167 °F) | (176 °F) | (194 °F) | (221 °F) | (257 °F) | (392 °F) | |
| Temperature rating of conductor | 0.58 | 0.75 | 0.78 | 0.82 | 0.85 | 0.89 | 1.00 |
| 2. See the following table: | Correction | ||||||
| factor | |||||||
| Number of current carrying conductors: | |||||||
| 3 | 0.70 | ||||||
| 4 to 6 | .60 | ||||||
| 7 to 24 | .50 | ||||||
| 25 and above | .40 | ||||||
[CGD 73-217, 42 FR 5944, Jan. 31, 1977; 42 FR 24739, May 16, 1977, as amended by CGD 81-092, 48 FR 55736, Dec. 15, 1983]