By Joe Schomaker and Todd Lottmann, Cooper BussmannIT HAS BEEN a long-standing requirement that conductors smaller that 14 AWG shall not be used in branch circuits. The industrial machinery industry has expressed a need to use smaller conductors, similar to those allowed by the International Electrotechincal Commission (IEC). An engineering-based analysis was completed on the properties of 16 and 18 AWG conductors. This analysis, developed by the NFPA 79 Small Wire Working Group was designed to cover typical worst case overcurrent conditions that could occur in various types of electrical distribution systems, and will be discussed in this paper. A Special Service Investigation was performed by UL to verify the premise and the testing results. This investigation was submitted to the full NFPA 79 committee to substantiate the inclusion of 16 and 18 AWG conductors for branch circuits in the 2002 edition.