Disclaimer

Reference values

The tables and calculators on this site show values from the NEC edition named on each page and from NIST publications. Use them for planning and learning.

Your jurisdiction decides

States and cities adopt different NEC editions, some years apart, and amend them. Your local electrical inspector, the authority having jurisdiction, has the final word on what an installation needs.

Equipment instructions

Listed equipment comes with installation instructions that can be stricter than a general table, for example on breaker size, wire size or terminal temperature. Follow them.

Who writes this site

The author is a physicist, not a licensed electrician or engineer. Have a licensed electrician do the work wherever your jurisdiction requires one.

Errors

If you find an error, email contact@wiresizes.com. Corrections are listed with dates on the About page.