Amps and Wire Gauge - 12V Circuit

Maximum current - amps - through a 12V circuit - related to size (AWG) and length of wire

Conductors in electrical systems 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).

Conductor size (AWG) related to maximum current through a 12V electrical wire and length of cable:

American Wire Gauge (AWG)
Length
(feet)
Maximum 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 adequate size may result in fire. Always secure electric wires with fuses.

  • 1 ft (foot) = 0.3048 m

Wire Gauge Design Procedure

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

Note! Wire sizes are based on 3% voltage drops in 12 Volt circuits. Oversize wires if 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

Related Documents

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