IEC 60268-22:2020-Sound system equipment-Part 22: Electrical and mechanical measurements on transducers, IEC 60335-2-111:2015-Household and similar electrical appliances-Safety-Part 2-111: Particular requirements for electric ondol mattress with a non-flexible heated part, IEC 60364-7-717:2009-Low-voltage electrical installations-Part 7-717: Requir