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Wire Amperage for 50V Plus


Technical article from www.Marinco.com

TECHNICAL INFORMATION


Table F: Allowable Amperage of Conductors of 50 Volts or More

The current values shown in Table F and also on Table D do not consider voltage drop for conductors under 50 volts. The values shown on the ampacity table are the maximum safe amperages which the conductor can carry on a continuous basis. They do not apply to intermittent starting loads such as motor start currents. Since all ANCOR Boat Cable is 105° C insulated, only that temperature rating is shown.

Due to the higher ambient temperatures in engine spaces and the heat retention of large wire bundles, a “correction factor” must be used to derate the wire by increasing conductor size. Table F takes into consideration these factors and should be used to select conductor sizes for circuits over 50 volts. Note that for electrical systems under 50 volts, voltage drop is the controlling factor and the tables on pages 14 and 15 should be used.

     2 Conductors 105° C (221° F) 3 Conductors 105° C (221° F) 4 to 6 Conductors 105° C (221° F) 7 to 24 Conductors 105° C (221° F)
Conductor Outside Inside Outside Inside Outside Inside Outside Inside
Size Engine Engine Engine Engine
(AWG) Space Space Space Space
18 20 17.0 14.0 11.9 12.0 10.2 10.0 8.5
16 25 21.3 17.5 14.9 15.0 12.8 12.5 10.6
14 35 29.8 24.5 20.8 21.0 17.9 17.5 14.9
12 45 38/3 31/5 26.8 27.0 23.0 22.5 19.1
10 60 51.0 42.0 35.7 36.0 30.6 30.0 25.5
8 80 68.0 56.0 47.6 48.0 40.8 40.0 34.0
6 120 102.0 84.0 71.4 72 61.2 60.0 51.0
4 160 136.0 112.0 95.2 96.0 81.6 80.0 68.0
3 180 153.0 126.0 107.1 108.0 91.8 90.0 76.5
2 210 178.5 147.0 125.0 126.0 107.1 105.0 89.3
1 245 208.3 171.5 145.8 147.0 125.0 122.5 104.1
1/0 285 242.3 199.5 169.6 171.0 145.4 142.5 121.1
2/0 330 280.5 231.0 196.4 198.0 168.3 165.0 140.3
3/0 385 327.3 269.5 229.1 231.0 196.4 192.5 163.6
4/0 445 378.3 311.5 264.8 267.0 227.0 222.5 189.1



Table F is supplied to eliminate the need for calculating the corrections for multi-conductor cable bundles to Table E. The values are already corrected.
Number of current Correction
carrying conductors: Factor
3 0.70
4 to 6 0.60
7 to 24 0.50
25 and above 0.40

  • Note: These tables only apply for 105° C (221° F) wire and other premium wire and should not be used for lesser grades of wire and cable.
  • Reprinted at the courtesy of the United States Coast Guard Electrical System Compliance Guideline.
*There is NO LIMIT on conductors in a bundle under 50 Volts.

Chart for wires carrying amperage under 50 Volts

Original article from Ancor

Electrical Guides from Marinco Group Brands

Ancor Guide- Features and Benefits (pdf)

Marinco- A Boaters Guide to AC Electrical Systems (pdf)


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