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What wire gauge should I use for my project ?  

We are not expert electricians, however we can give you guidelines based on the chart below.

To calculate the wire gauge you will need for your application, you need to know 3 (three) variables.

  1. The voltage 12V or 24V
  2. The lenght of your circuit, noting that the lenght is the " round trip " distance from the panel or the battery  to the load an back.
  3. The Amp drawn by the load.  If you do not know the Amp drawn by your instrument but know the voltage and the wattage, just use this simple formula:  amp = watts / volts    

Let's look at an example:

You want to install a 65 Watt 12 V searchlight which will be located 20 feet from the distribution panel. 

We need to figure out the Amps. The amps = watts / volts, so 65 Watts / 12V = 5.4 Amps.

The round trip circuit lenght is 40 feet (20 feet X 2) 

The 12 Volts charts gives us a wire gauge  #10 for 5 amps on a 40 to 60 feet circuit.

In ideal condition* a #10 AWG wire should be sufficient.


*Please take note:

These charts assume:

  1. 105 o C wire insulation rating.  Lower insulation rating cannot handle as much current.
  2. AWG wire sizes, not SAE.   All our wires are AWG.  SAE wire sizes are 6% to 12% smaller.
  3. Wires are not run in engine spaces. Maximum current is 15% less in engine spaces, which are assumed to be 20 o C hotter than non-engine spaces (50 o C vs 30 o C)
  4. Conductors are not bundled.  If three conductors are bundled, reduce maximum amperage by 30%. If 4-6 conductors are bundled, reduce maximum amperage by 40%. If 7-12 conductors are bundled, reduce amperage by 50%.


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