The charts below show the maximum lengths of cable you can use while still maintaining a three percent voltage drop for the given wire size (or AWG, which stands for American Wire Gauge) and circuit voltage.

Buried or underground electrical service entry cable ampacity & underground electrical service ampacity ratings: what are the required electrical cable sizes & types, conduit sizes, and burial depths for underground electrical service entry wiring?

Southwire's cable tray fill calculator takes the guesswork out of your project. Get accurate results and stay within NEC guidelines.

The American Wire Gauge (AWG) system provides standard wire gauge sizes. The higher the number of the gauge, the smaller the size of the wire. See the AWG chart below for examples. The National Electrical Code (NEC) mandates the regulations for wire and cable that can be used for electrical applications. Key Definitions

The wire size chart below shows allowable ampacities of insulated conductors rated up to and including 2000 Volts, 60°C through 90°C (140°F through 194°F), not more than three current-carrying conductors in raceway, cable, or earth (directly buried), based on ambient air temperature of 30°C (86°F).