Question: What is ampacity, as applied to conductors?
See the answer below.
Answer: Ampacity is the maximum current, in amperes, that a conductor can carry continuously under the conditions of use without exceeding its temperature rating (NEC Art. 100).
Explanation: Most everyone typically answers, "How much current a conductor can carry." While this is true it is only part of the answer. A conductor must carry the current continuously and in the conditions it is being used in. It must also carry the current without overheating. For these reasons the ampacity of a conductor is subject to adjustments in Sec. 310.15.
Lupacchino is a senior design engineer with Gaylor Electric, Inc. in Noblesville, Ind. and serves as an alternate on NEC Code-Making Panel No. 3. He is currently licensed in more than 80 jurisdictions. He can be reached at [email protected].