N.C. Gen. Stat. § 143-139.3

If the test required under the North Carolina State Building Code for a liquified petroleum gas piping system serving a one or two-family residential dwelling is not performed by a qualified code enforcement official, as defined in G.S. 143-151.8(a)(5), the contractor who installed the system shall verify that the system complies with the test requirements and shall certify the results, in writing, to the code official.