What NEC® code reference allows the use of steel threaded rigid couplings with aluminum rigid metal conduit?

The correct reference for using steel threaded rigid couplings with aluminum rigid metal conduit is found in section 344.14 of the National Electrical Code (NEC). This section addresses the requirements for fittings and couplings used in rigid metal conduit (RMC) installations.

Steel threaded couplings are permissible with aluminum rigid metal conduit because this combination ensures mechanical strength and allows for secure connections in electrical installations. The NEC establishes guidelines to ensure that materials can be used together safely, particularly in terms of compatibility and corrosion resistance. In this case, the code acknowledges that the physical attributes of aluminum and steel can coexist in specific applications, thus permitting their combination under certain conditions as defined in section 344.14 of the NEC.

The other sections listed refer to different types of electrical installations or conduit systems, and do not specifically address the compatibility of aluminum rigid metal conduit with steel fittings and couplings. This distinction underscores the relevance of 344.14 for this particular application.