Figure 1. Both cables are rated for 12,500 amps. The bottom cable is a superconductor.[1]

Ampacity (measured in amperes (A)) is the maximum current that can be safely carried by a given wire gauge (in the American wire gauge system). Lower wire gauges in the American Wire Gauge system, have higher ampacity, meaning that the wire can carry more current. As current passes through a wire, it gets a little hotter; the more current passing through the wire the hotter it gets. If the ampacity rating is surpassed the insulating material is susceptible to damages, and a fire can result[2].

As shown in figure 1, superconductors have a tremendously large ampacity compared to metal wire. Superconductors need to be very cold in order to function. If they go above their critical temperature, their resistance increases quite a bit!

For Further Reading

For further information please see the related pages below:


  1. By Rama - Own work, CC BY-SA 2.0 fr, accessed May 9th, 2018.
  2. "Conductor ampacity" internet: