The Ground Conductor Size Calculator will calculate the proper ground conductor size for grounding raceways and equipment based on ampere rating or setting of automatic overcurrent protection device in circuit ahead of equipment. This is based on NEC (NFPA 70®: National Electrical Code® (NEC®), 2014 Edition) Table 250.122.

Ground Wire Size Calculator


Enter the information below to calculate the appropriate ground conductor size.



Wire Conductor Material Wire Size (AWG or kcmil)
Copper -
Aluminum -

Note: Always comply with NEC when equipment grounding conductor should be sized larger than the values listed in this calculator.

Source: NFPA 70, National Electrical Code, Table 250.122

To calculate wire size for a circuit, use the Wire Size Calculator or the Advanced Wire Size Calculator. To calculate wire ampacity for a circuit, use the Wire Ampacity Calculator or the Advanced Wire Ampacity Calculator.


For long conductor runs where voltage drop may be an issue, use the Voltage Drop Calculator to determine proper conductor sizing and maximum circuit length. Visit the Tables page to view reference tables such as Maximum Ampacity for Current-Carrying Conductors.


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