Electrical Systems - Manufacturer Requirements
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FEDERAL LAW
183.425 - Conductors: General
(a) Each conductor must be insulated, stranded copper.
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Each conductor must be insulated with an insulation compound meeting:
- Sec. 183.430, if less than 50 volts, or
- Sec. 183.435, if 50 volts or more.
The conductor must be stranded to resist failure due to vibration and flexing. Copper is specified for the best combination of conductivity and corrosion resistance.
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TO COMPLY WITH THE LAW
- The conductor insulation material conforms to either 183.430 or 183.435 depending on the voltage application (less than 50 volts, or 50 volts or more).
- The construction is of stranded copper (note permitted exceptions in 183.425(g)).
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FIGURE 18 - Insulated Stranded Copper Conductor
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FEDERAL LAW
183.425 - Conductors: General
(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.
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The current values referred to in Table 5 are constant or steady values as compared with the intermittent higher currents which may occur momentarily in circuits, such as those associated with stern-drive trimming devices or electrical motor starting situations. To select a conductor size use the maximum steady state load.
Due to engine heat, the ambient temperature in engine spaces is usually higher than in other spaces of the boat. Wiring in and passing through engine spaces must be able to operate at these higher ambient temperatures. The ampacity values in Table 5 are based on an ambient temperature of 30° C (86° F), which is considered reasonable for use on boats except in engine spaces. The correction factors of Note 1 in Table 5 convert the ampacities of Table 5 to acceptable values in an ambient temperature of 50° C (122° F). This higher temperature has been selected as satisfactory for engine spaces.
Tables 5A through 5E are supplied to eliminate the need for calculating the corrections to Table 5 (see Notes 1 and 2 under Table 5). The values are already corrected. Sample calculations appear under the discussion of section 183.435 (a) later in this guideline.
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TO COMPLY WITH THE LAW
- Conductor gauge and temperature ratings are selected to carry current equal to, or less than, the values given in Table 5 (and associated Tables 5A through 5E).
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TABLE 5 - Allowable Amperage of Conductors
TABLE 5A - No More Than 2 Conductors are Bundled
TABLE 5B - 3 Conductors Are Bundled
TABLE 5C - 4 to 6 Conductors Are Bundled
TABLE 5D - 7 to 24 Coductors Are Bundled
TABLE 5E - 25 or More Conductors Are Bundled
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FEDERAL LAW
183.425 - Conductors: General
(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.
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A conductor smaller than 16 AWG may not be used by itself. An 18 AWG is the smallest conductor permitted, except for the regulatory exceptions, and it must be in a multiconductor (2 or more conductors) sheath.
An 18 AWG conductor is limited to a 30 inch length from the end of a sheath. (See Figure 19).
NOTES:
SAE conductor sizes are acceptable in place of AWG.
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FEDERAL LAW
183.425 - Conductors: General
(g) This section does not apply to communication systems; electronic navigation equipment; electronic circuits having 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.
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TO COMPLY WITH THE LAW
- No conductor smaller than No. 16 AWG is used separately.
- Any No. 18 AWG conductor used is protected in a suitable multiconductor sheath and does not extend out of this sheath more than 30 inches.
NOTE PERMITTED EXCEPTIONS in 183.425 (g)
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FIGURE 19 - Permitted Conductor Size
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