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 sizes (AWG) related to maximum current through a 12V electrical copper wire and length of cable - are indicated below:
|Maximum Current (amps)|
Note! Failure to use an adequate size may result in a fire. Always secure electric wires with fuses.
- 1 ft (foot) = 0.3048 m
Wire Gauge Design Procedure
- calculate total length of wire from source to device and back again
- determine amount of current in wire
- determine correct wire gauge in the intersection of amps and feet
Note! Wire size based on 3% (0.36 V) voltage drop in a 12 Volt circuit. Always oversize wires if voltage drop is critical.
print 12V Cable Length Diagram
Example - 12 V Cable and Maximum Length and Current
The maximum current in a 12 V gauge #6 (13.3 mm2) cable with length 15 m is approximately 15 amps according the diagram above.
The maximum current in a gauge #10 (5.26 mm2) cable with length 15 m is approximately 5 amps.
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