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

The reference to the NEC code that permits the use of steel threaded rigid couplings with aluminum rigid metal conduit is indeed found in 344.14. This section specifically addresses the provisions for using nonferrous materials with ferrous components, allowing for the appropriate types of fittings and fixtures to be utilized. It is crucial in ensuring the integrity of connections and maintaining the overall effectiveness and safety of the conduit system.

In the context of this question, understanding that 344.14 focuses explicitly on the acceptable usages concerning aluminum and steel components helps illustrate its importance in practical applications, such as preventing galvanic corrosion that can arise from inappropriate combinations of metals in electrical installations. This is why 344.14 is the correct reference, supporting safe and code-compliant electrical work when combining different types of conduit materials.