APPENDIX 69 ancorproducts.com 10% Voltage Drop at 12 Volts Current (Amps) Length 5 10 15 20 25 30 40 50 60 70 80 90 100 10' 3 m 18 18 18 16 16 14 14 12 12 10 10 10 10 15' 5 m 18 18 16 14 14 12 12 10 10 8 8 8 8 20' 6 m 18 16 14 14 12 12 10 10 8 8 8 6 6 25' 8 m 18 16 14 12 12 10 10 8 8 6 6 6 6 30' 9 m 18 14 12 12 10 10 8 8 6 6 6 6 4 40' 12 m 16 14 12 10 10 8 8 6 6 6 4 4 4 50' 15 m 16 12 10 10 8 8 6 6 4 4 4 2 2 60' 18 m 14 12 10 8 8 6 6 4 4 2 2 2 2 70' 21 m 14 10 8 8 6 6 6 4 2 2 2 2 1 80' 24 m 14 10 8 8 6 6 4 4 2 2 2 1 1 90' 27 m 12 10 8 6 6 6 4 2 2 2 1 1 1/0 100' 30 m 12 10 8 6 6 4 4 2 2 1 1 1/0 1/0 110' 33 m 12 8 8 6 6 4 2 2 2 1 1/0 1/0 1/0 120' 36 m 12 8 6 6 4 4 2 2 1 1 1/0 1/0 2/0 130' 40 m 12 8 6 6 4 4 2 2 1 1/0 1/0 2/0 2/0 140' 43 m 10 8 6 6 4 2 2 1 1 1/0 2/0 2/0 2/0 150' 46 m 10 8 6 4 4 2 2 1 1/0 1/0 2/0 2/0 3/0 160' 49 m 10 8 6 4 4 2 2 1 1/0 2/0 2/0 3/0 3/0 170' 52 m 10 6 6 4 2 2 2 1 1/0 2/0 2/0 3/0 3/0 10% Voltage Drop at 24 Volts Current (Amps) Length 5 10 15 20 25 30 40 50 60 70 80 90 100 10' 3 m 18 18 18 18 18 18 16 16 14 14 14 12 12 15' 5 m 18 18 18 18 16 16 14 14 12 12 12 10 10 20' 6 m 18 18 18 16 16 14 14 12 12 10 10 10 10 25' 8 m 18 18 16 16 14 14 12 12 10 10 10 8 8 30' 9 m 18 18 16 14 14 12 12 10 10 8 8 8 8 40' 12 m 18 16 14 14 12 12 10 10 8 8 8 6 6 50' 15 m 18 16 14 12 12 10 10 8 8 6 6 6 6 60' 18 m 18 14 12 12 10 10 8 8 6 6 6 6 4 70' 21 m 16 14 12 10 10 8 8 6 6 6 6 4 4 80' 24 m 16 14 12 10 10 8 8 6 6 6 4 4 4 90' 27 m 16 12 10 10 8 8 6 6 6 4 4 4 2 100' 30 m 16 12 10 10 8 8 6 6 4 4 4 2 2 110' 33 m 14 12 10 8 8 8 6 6 4 4 2 2 2 120' 36 m 14 12 10 8 8 6 6 4 4 2 2 2 2 130' 40 m 14 12 10 8 8 6 6 4 4 2 2 2 2 140' 43 m 14 10 8 8 6 6 6 4 2 2 2 2 1 150' 46 m 14 10 8 8 6 6 4 4 2 2 2 2 1 160' 49 m 14 10 8 8 6 6 4 4 2 2 2 1 1 170' 52 m 12 10 8 6 6 6 4 2 2 2 2 1 1 10% Voltage Drop at 32 Volts Current (Amps) Length 5 10 15 20 25 30 40 50 60 70 80 90 100 10' 3 m 18 18 18 18 18 18 18 16 16 14 14 14 14 15' 5 m 18 18 18 18 18 18 16 14 14 14 12 12 12 20' 6 m 18 18 18 18 16 16 14 14 12 12 12 10 10 25' 8 m 18 18 18 16 16 14 14 12 12 10 10 10 10 30' 9 m 18 18 18 16 14 14 12 14 10 10 10 10 8 40' 12 m 18 18 16 14 14 12 12 10 10 8 8 8 8 50' 15 m 18 16 14 14 12 12 10 10 8 8 8 6 6 60' 18 m 18 16 14 12 12 10 10 8 8 8 6 6 6 70' 21 m 18 14 14 12 10 10 8 8 8 6 6 6 6 80' 24 m 18 14 12 12 10 10 8 8 6 6 6 6 4 90' 27 m 18 14 12 10 10 10 8 6 6 6 6 4 4 100' 30 m 16 14 12 10 10 8 8 6 6 6 4 4 4 110' 33 m 16 14 12 10 10 8 8 6 6 6 4 4 4 120' 36 m 16 12 10 10 8 8 6 6 6 4 4 4 2 130' 40 m 16 12 10 10 8 8 6 6 6 4 4 2 2 140' 43 m 14 12 10 8 8 8 6 6 4 4 2 2 2 150' 46 m 14 12 10 8 8 6 6 6 4 4 2 2 2 160' 49 m 14 12 10 8 8 6 6 4 4 2 2 2 2 170' 52 m 14 12 10 8 8 6 6 4 4 2 2 2 2 Use 10% voltage drop for any “non-critical” applications: windlass, cabin lights, etc.... For Example... Q: A bilge pump draws 10 amps. The positive run is 11 feet from the power panel, including the float switch. The negative run is only 10 feet. What size is the wire? A: Use the formula to reach the correct answer: CM = 10.75 x 10 (amps) x 21 (total length of run) 0.36 (3% of 12V) = 6,271 Ancor cable specifications show that 12 AWG wire has a CM area of 6,500 and is the correct choice. However, SAE wire has a CM area of only 5,833. Under NFPA and USCG regulations, 10 SAE wire must be used. Conductors Sized (AWG) for 10% Voltage Drop ABYC Recommends… “Conductors used for lighting, other than navigation lights, and other circuits where voltage drop is not critical, shall be sized for a voltage drop not to exceed 10 percent.” ABYC 11.16.1.2.7. TECH TIP
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