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12 Volt Wire Size Calculator

Last updated: July 25, 202454 people find this calculator helpful
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The 12-volt wire size calculator will help determine the appropriate electrical wire for your next house installation. Do you want to install a new camera or motion-sensing light? Please keep reading to determine how to size your cables.

How to calculate the size of a 12 volt wire?

We will use the resistivity concept and combine it with the ohm's law for a single conductor:

A=V×%drop2×IϱLA=V×%drop2×IϱL

where:

  • %drop%drop — Allowable voltage drop, in %.
  • VV — Source voltage, measured in volts.
  • II — Maximum current running through the wire, measured in amps;
  • ϱϱ — Resistivity of the conductor material, measured in ohm meters;
  • LL — Length of the wire, measured in meters; and
  • AA — Cross-sectional area of the wire measured in square meters.

We add factor 2 because we have one way from the source to the equipment and another one way from the equipment to the source.

How do you use this 12 V wire size calculator?

You need to verify that your equipment can withstand 12 volts. Then you follow these steps:

  1. 12-volt AC / DC is already set for you. Now, we have to define the allowable voltage drop.

  2. Select the conductor's material, either copper or aluminum. You can also select Other to enter a custom conductor resistivity value.

  3. Define how much current (amperes) your equipment needs.

  4. Indicate the one-way length of your electrical system.

  5. Finally, specify the maximum operating temperature.

Our 12 V wire size calculator will indicate the cross-sectional area, cable diameter, and AWG size.

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FAQs

Which size wire is recommended for 12 volts appliances?
You have to define the amperes your equipment needs as it directly impacts the 12-volt wire size calculation. However, if we: Include the allowable voltage drop (maximum 5% for DC appliances). Finally, add the one-way length of our system (here, we assume 7 m) and the max operating temperature; then, we get a 13 AWG wire.
Can I use 16 AWG wire for 12 volts applications?
It will depend on the maximum current you will have in the conductor. Add the maximum wire area corresponding to 16 AWG: 1.308 mm². Set the maximum operating temperature. By default, 50 °C. Define the one-way distance (5 meters) and the maximum allowable voltage drop (3%). As a result, the maximum current is 2.5 amperes.
How many amps can a 14 AWG wire withstand on a 12-volts system?
To get such a result, we need: Add the wire area corresponding to 14 AWG: 2.08 mm². Add a one-way distance of 5 meters. Include an allowable voltage drop of 3%. Define a maximum operating temperature of 50 °C.

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