Wire Guage? This topic contains 3 replies, has 2 voices, and was last updated by Erik I. 1 year, 2 months ago. Author Posts July 19, 2016 at 11:28 am #7470 Thomas FinleyParticipant What gauge wire should I use for a 30 Amp circuit? July 19, 2016 at 11:50 am #7471 Erik I.Galco Representative A circuit fused for 30 Amps must use a minimum of 10 gauge copper wire. Longer runs may require a larger wire size. What’s your application? July 19, 2016 at 2:18 pm #7472 Thomas FinleyParticipant It will be a short run, less than 20 feet July 19, 2016 at 2:29 pm #7473 Erik I.Galco Representative You will be good with the 10 gauge Author Posts You must be logged in to reply to this topic.