plug Portable appliance testing References Sources IEC 61140: Protection against electric shock — Common aspects for installation and equipment. International Electrotechnical Commission. 2001. (formerly: IEC 536-2: Classification of electrical and electronic equipment with regard to protection against electric shock, 1992) BS 2754 : 1976 (1999): Memorandum. Construction of electrical equipment for protection against electric shock. Electric power IEC standards