The requirements in the 2015 International Mechanical Code (IMC) broaden the application of the UL 2043 Standard for Fire Test for Heat and Visible Smoke Release for Discrete Products Installed in Air-Handling Spaces. Compliance with UL 2043 was already a requirement for discrete electrical products in plenums, and the 2015 IMC requires discrete plumbing and mechanical products to comply with UL 2043 as well.

To determine the fire performance response of discrete products (including, but not limited to electrical, mechanical, and plumbing equipment) intended to be installed in air handling spaces, such as above suspended ceilings or below floors. The purpose of this test is to determine the rate of heat release and the rate of smoke release of the burning product samples as they relate to the requirements for fire-resistant and low-smoke-producing characteristics.

Discrete products (including, but not limited to electrical, mechanical, and plumbing equipment). Additionally, discrete, non-continuous building materials where the Test for Surface Burning Characteristics of Building Materials, UL 723, is not applicable.