For the majority of DC/DC converter applications in the telecommunications and datacommunications equipment, the applicable safety standards are UL1950 (and its Canadian equivalent C22.2 No. 950-95) for North America and EN60950 for Europe. Both are titled «Standards for Safety of Information Technology Equipment (ITE), Including Electrical Business Equipment,». 2- UL1950/EN60950 Safety Principle These safety standards address construction issues and are intended to prevent injury to equipment operators and service personnel as well as other forms of damage caused by : - Electric shock, - Energy hazards, - Fire, - Mechanical and heat hazards, - Radiation Hazards, - Chemical Hazards. Electric shock is due to current passing through the human body. Currents of the order of a milliampere can cause a reaction in persons in good health and may cause indirect danger due to involuntary reaction. Higher currents can have more damaging effects. Voltages up to about 40Vac peak, or 60Vdc, are not generally regarded as dangerous under 1- General dry conditions, but parts which have to be touched or handled should be at earth potential or properly insulated. It is normal to provide two levels of protection for operators to prevent electric shock. Energy Hazards can be caused by arcing or ejection of molten metal when adjacent poles of high current supplies or high capacitance circuits are short-circuited. Protection is made by separation, by shielding or by using safety interlocks. Fire risks may result from overloads, component failure, insulation breakdown or loose connections. Fires should not spread beyond the immediate vicinity of the source of the fire or cause damage to the surroundings of the equipment. Mechanical and heat hazards should be prevented by providing adequate stability, by avoiding sharp edges and points or by restricting access to dangerous parts. Radiation Hazards encountered can be sonic, radio frequency, infra-red, high intensity visible and coherent light, ionising, etc. Requirements are necessary to keep person exposures to acceptable levels. Chemical Hazards through contact with chemicals, their vapours and fumes are required to be limited under normal and abnormal conditions.