“CEN” (COMITÉ EUROPÉEN DE NORMALISATION) is used as a catch all term for the current lot of Harmonised EU standards for bicycles:
BS EN 14764:2005 – City and trekking bicycles — Safety requirements and test methods
BS EN 14765 – Bicycles for young children — Safety requirements and test methods
BS EN 14766:2005 – Mountain-bicycles — Safety requirements and test methods
BS EN 14781:2005 – Racing Bicycles – Safety Requirements and Test Methods
apparently bureau veritas are accredited to conduct the testing described in most of the of the above Standards with a couple of minor exceptions, as well as as well as BS 6102-1:1992 – Cycles — Part 1: Specification for safety requirements for bicycles, which might now be superseded by the EN suit of standards (anyone know?)
EN 14765 would probably be most appropriate/applicable for a Balance bike I’d have thought…