household and similar electrical appliances safety part 2-21 particular requirements for storage water heaters 21 pages in english this international standard deals with the safety of electric storage water heaters for household and similar purposes and intended for heating water below boiling temperature their rated voltage being not more than 250 v for single phase appliances and 480 v for other appliances. appliances not intended for normal household use but that nevertheless may be a source of danger to the public such as appliances intended to be used by laymen in shops and in light industry and farms are within the scope of the standard. as far as is practicable this standard deals with the common hazards presented by the appliances that are encountered by all persons in and around the home. however in general it does not take into account -persons including children whose physical sensory or mental capabilities or lack of experience and knowledge prevents them from using the appliance safely without supervision or instruction -children playing with the appliance. note 101 attention is drawn to the fact that -for the appliances intended to be used at high altitudes additional requirements may be necessary -for the appliances intended to be used in vehicles or on board ships or aircraft additional requirements may be necessary -in many countries additional requirements are specified by the national health authorities the national authorities responsible for the protection of labour and similar authorities -in many countries regulations exist for the installation of equipment connected to the water mains. note 102 this standard does not apply to -appliances for boiling water iec 60335-2-15 -instantaneous water heaters iec 60335-2-35 -commercial dispensing appliances and vending machines iec 60335-2-75 -appliances intended exclusively for industrial purposes -appliances intended to be used in locations where special conditions prevail such as the presence of a corrosive or explosive atmosphere dust vapour or gas .