Recommendation ITU-T K.51 provides guidance on safety criteria for telecommunication network infrastructure equipment. It specifies requirements intended to reduce risks of fire,electric shock or injury for the operator,layman and service personnel who may come into contact with the equipment.This Recommendation refers to IEC 60950-1 and provides additional requirements when these are not covered by IEC 60950-1.Equipment complying with the relevant requirements in this Recommendation is considered suitable for use in a telecommunication network.However,this Recommendation does not include requirements for performance or functional characteristics ofequipment.