BS IEC 6100027:19981BS IEC 6100027:19982 BSI 1998BS IEC 6100027:19983BS IEC 6100027:19984BS IEC 6100027:19985BS IEC 6100027:19986BS IEC 6100027:19987BS IEC 6100027:19988BS IEC 6100027:19989BS IEC 6100027:199810BS IEC 6100027:199811BS IEC 6100027:199812BS IEC 6100027:199813BS IEC 6100027:199814BS IEC 6100027:199815BS IEC 6100027:199816BS IEC 6100027:199817BS IEC 6100027:199818BS IEC 6100027:199819BS IEC 6100027:199820BS IEC 6100027:199821BS IEC 6100027:199822BS IEC 6100027:199823BS IEC 6100027:199824BS IEC 6100027:199825BS IEC 6100027:199826BS IEC 6100027:199827BS IEC 6100027:199828