CASE COMMENT: We have a Chiller Refrigeration Machinery Room with a Natural Gas Fired Water Cooled Chiller that uses R-134A (Safety Group A1. The room also contains various Electrical Equipment for the building, including the main breaker, Automatic Transfer Switch, and the 460 Volt to 120 Volt Transformer that then serves the Chiller. Per UMC 1108.2 the Electrical Equipment install meets the Electrical Code. However, the State Inspector is citing 1109.1 and has indicated that extra electrical equipment may not be in the same room as the Chiller. The City Building inspector is completely fine with the install. RESPONSE: Yes, Electrical Equipment that serves the Chiller and also other Equipment in the building may reside in the same room as the chiller, provided the refrigerant is Group A1. The electrical equipment that serve the chiller room needs to meet section 1108.2 of the 2024 Uniform Mechanical Code. Electrical equipment that is essential for the refrigeration process, maintenance of the equipment, or for the illumination of the room can be placed in the machinery room as long as the electrical equipment complies with the electrical code, whereas electrical equipment that serves solely other parts of a building cannot be placed in a machinery room. As stated in the comment the chiller uses a safe refrigerant classed A-1 and most of the equipment listed serves the refrigeration process in one way or another therefore the Authority Having Jurisdiction deemed them safe and essential to the process, Exclusion would be applied to equipment, piping, ducts, vents, or similar devices that are not essential for the refrigeration process. If it is not essential for the chiller room it clearly states that it shall not be in the chiller room under the provisions of section 11098.1 of the 2024 Uniform Mechanical Code. In describing this specific Refrigeration Machinery Room the equipment serves both the chiller and other equipment in the building. Sections 1107.1.8, 1108.1 and 1108.2 of the 2024 Uniform Mechanical Code state that the machinery rooms with Safety Group A1 or B1 refrigerants are not required to be classified as a Class1, Division1 hazardous location; and when other refrigerants are used, instances the machinery room would be considered either a Class1, Division1 or Class1, Division 2 hazardous location for the fans and associated equipment to operate the emergency purge of the machinery room. The flammability ratings increase in Safety Group A2 and A3, or B2 refrigerants; while both the flammability along with the toxicity increase in the Safety Group B3 refrigerants. The intent of the UMC is to recognize the use of certain refrigerants if properly treated are not necessarily any more dangerous to work in than other locations. In those machinery rooms where other than Safety Group A1 or B1 refrigerants are used, the electrical components of the fans and associated equipment to operate the emergency purge of the machinery room would need to intrinsically safe.