Boat Building Regulations | Boat Electrical Systems Wiring | Voltage Drop

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ELECTRICAL SYSTEMS
Voltage Drop

This table is from ABYC. There are tables for 24 volts and 32 volts, and for AC systems. Contact ABYC for a copy of E-11, AC and DC Electrical Systems on Boats.

Table to determine wire size due to voltage drop based on the length of the wire. This table is for 12 volts only.

Length of conductor from power source to the device and back to the power source
Feet	10	15	20	25	30	40	50	60	70	80	90	100	110	120	130	140	150	160	170
Total Amps	12 volt - 10% drop wire sizes gauge
5	18	18	18	18	18	16	16	14	14	14	12	12	12	12	12	10	10	10	10
10	18	18	16	16	14	14	12	12	10	10	10	10	8	8	8	8	8	8	6
15	18	16	14	14	12	12	10	10	8	8	8	8	8	6	6	6	6	6	6
20	16	14	14	12	12	10	10	8	8	8	6	6	6	6	6	4	4	4	4
25	16	14	12	12	10	10	8	8	6	6	6	6	6	4	4	4	4	4	2
30	14	12	12	10	10	8	8	6	6	6	6	4	4	4	4	2	2	2	2
40	14	12	10	10	8	8	6	6	6	4	4	4	2	2	2	2	2	2	2
50	12	10	10	8	8	6	6	4	4	4	2	2	2	2	2	1	1	1	1
60	12	10	8	8	6	6	4	4	2	2	2	2	2	1	1	1	0	0	0
70	10	8	8	6	6	6	4	2	2	2	2	1	1	1	0	0	0	2/0	2/0
80	10	8	8	6	6	4	4	2	2	2	1	1	0	0	0	2/0	2/0	2/0	2/0
90	10	8	6	6	6	4	2	2	2	1	1	0	0	0	2/0	2/0	2/0	3/0	3/0
100	10	8	6	6	4	4	2	2	1	1	0	0	0	2/0	2/0	2/0	3/0	3/0	3/0