Many standards have Published for calculating of current carrying capacity for bare overhead conductors. Although these standards use the same basic heat balance concept, they use different approaches to calculate current carrying capacity, This paper looks at the four approaches used to calculate individual heat balance terms, at the overall impact of these terms on the current carrying capacity And this paper is proposed to the selection of proper standard and AC resistance within a country conditions for calculating the current carrying capacity of bare overhead conductors. So current carrying capacities are Proposed to some of conductors.