33 CFR §183.425

1. (a)Each conductor must be insulated, stranded copper.
2. (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.
3. (c)For conductors in engine spaces, amperages must be corrected by the appropriate correction factor in note 1 of Table 5.
4. (d)Each conductor in a multiconductor sheath must be at least a No. 18 AWG conductor.
5. (e)Each conductor installed separately must be at least a No. 16 AWG conductor.
6. (f)Each No. 18 AWG conductor in a multiconductor sheath may not extend out of the sheath more than 30 inches.
7. (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.