Amps and Wire Gauge - 12V Circuit

Maximum current - amps - through a 12V circuit in combination with size (AWG) and length of wire

In an electrical systems the conductors should not be sized with voltage drops exceeding 3%. For a 12V system the maximum voltage drop should be less than 12 (V) x 3% = 0.36 (V).

The table below can be used to determine the combination of maximum current through a 12V electrical wire, size (AWG) and length of cable.

American Wire Gauge (AWG)
Length
(feet)
Current (amps)
5 10 15 20 25 30 40 50 60 70
15 16 12 10 10 8 8 6 6 4 4
20 14 12 10 8 8 6 6 4 4 4
25 14 10 8 8 6 6 4 4 2 2
30 12 10 8 6 6 4 4 2 2 2
40 12 8 6 6 4 4 2 2 1 1/0
50 10 8 6 4 4 2 2 1 1/0 1/0
60 10 6 6 4 2 2 1 1/0 2/0 2/0
70 10 6 4 2 2 2 1/0 2/0 2/0 3/0
80 8 6 4 2 2 1 1/0 2/0 3/0 3/0
90 8 4 4 2 1 1/0 2/0 3/0 3/0 4/0

Note! Failure to use an adequate size may result in fire. Always secure a wire with a fuse.

  • 1 ft (foot) = 0.3048 m

Wire Gauge Design Procedure

  1. calculate the total length of the wire from the source to the device and back again
  2. determine the amount of current in the wire
  3. correct wire gauge is in the intersection of amps and feet

Note! The wire size is required for a 3% voltage drop in 12 Volt circuits. Oversize the wire if the voltage drop is critical.

12 v cable length maximum amps

Related Topics

  • Electrical - Amps and electrical wiring, AWG - wire gauge, electrical formulas, motors and units

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