UL 923
1 Scope
1.1 These requirements cover household and commercial microwave cooking appliances operated in the Industrial, Scientific and Medical (ISM) bands of 915 25 and 2450 50 MHz, for use in ordinary locations in accordance with the National Electrical Code, NFPA 70, and rated not more than 600 V.
1.2 These requirements also cover microwave cooking appliances intended for built-in installation, side-by-side mounting, stacking, wall mounting and installation over ranges.
1.3 For the purpose of these requirements, commercial microwave cooking equipment is that usually found in commercial kitchens, restaurants, or other business establishments where food may be dispensed. Household microwave cooking equipment is that intended for household use.
1.4 These requirements also cover the microwave cooking portion of a household electric range. The combination is to comply with the Standard for Household Electric Ranges, UL 858.