440.9 Rooftop Air-Conditioning Equipment Grounding Conductor – https://www.MikeHolt.com/code. You may already be aware that metal raceways such as RMC and EMT are suitable equipment grounding conductor types, but what about where roof-top air-conditioning equipment (roof-top units or RTUs) is concerned? Discover the unique requirements for RTUs in this podcast about section 440.9 in the NEC.