Maximum Current Carrying Capacity of Cables/ Wires

It’s known that current carrying capacity of a wire varies based on the conductor in your cables/wires. Current carrying capacity is largely dependent on the melting point of either the conductor or insulator of the cable. When current is passing through the conductors, heat is generated. Knowing this, how can we maximize the current our cables can carry?


Theoretically the amount of current can be increased until the heat it generates reaches the melting temperature of copper. This would not be good for your system, however. In general, a wire’s maximum current will depend on the end operating conditions and any methods used to increase heat dissipation. Please note the below factors; they will limit the amount of current that can run through your wiring when choosing cables/wires.

  1. Conductor Size:
    The larger the circular cross-sectional area of the conductor, the greater the current carrying capacity.
  2. Ambient Temperature:
    The higher the ambient temperature, the less current-based heat is required to reach the maximum temperature rating of the insulation, and thus the lower the current carrying capacity.
  3. Conductor Number:
    Bundling individual conductors together numbers causes them to heat each other up, reducing heat dissipation and current capacity.
  4. Installation:
    Installing the conductors in conduits, ducts or trays will limit heat dissipation. This issue can be alleviated with forced-air cooling, which will also help with other heat dissipation issues…

For more information, please see this general guide offered by Tensility on cable current ratings by AWG and jacketing material.

conductor current capacity.pdf (807.2 KB)

Note: the attached is a very general guideline for reference only. Neither Tensility nor Digi-Key can make guarantees of current capability in your specific application; you should run all appropriate tests to ensure that whatever cabling you choose will work for your application.