An electric cable, which includes at least one conductor and an insulating layer surrounding the conductor, wherein an insulating composition for forming the insulating contains a non-crosslinked polypropylene comprising a reactive polypropylene selected from the group consisting of an ethylene-propylene rubber, an ethylene-propylene-diene rubber (EPDM), or mixtures thereof, and polypropylene, which has a softening point higher than that of the reactive polypropylene, comprising at least one selected from the group consisting of random polypropylene, homopolypropylene and block polypropylene, so that the conductor has a maximum allowable temperature of 110°C to 120°C, and wherein when the conductor has a nominal cross-sectional area specified in IEC Standards 60502-2, the conductor has a maximum allowable current higher by at least 10% than a maximum allowable current calculated by Equation 1 I = Δ θ − W d 0.5 T 1 + n T 3 + T 4 RT 1 + nR 1 + λ 1 T 3 + L f ⋅ T 4 1 / 2 I: maximum allowable current of a conductor △θ: a value obtained by subtracting an atmospheric temperature from a maximum allowable temperature (°C) (a maximum allowable current of a conductor surrounded by an insulating layer made of crosslinked polyethylene is set to be 90°C, a maximum allowable current of a conductor surrounded by an insulating layer made of non-crosslinking polypropylene is set to be 110°C, and the atmospheric temperature is set to be 30°C) W d: dielectric loss per unit length of the insulating layer surrounding the conductor (W/m) T 1: thermal resistance per unit length between the conductor and the sheath layer (K.m/W) T 3: thermal resistance of the sheath layer (K.m/W) T 4: thermal resistance out of the sheath layer (K.m/W) R: AC resistance per unit length of the conductor at a maximum allowable temperature of the conductor (Ω/m) n: the number of conductors included in the cable λ 1: circuit loss factor L f: load loss factor wherein an insulating composition for forming the insulating contains a non-crosslinked polypropylene comprising a reactive polypropylene selected from the group consisting of an ethylene-propylene rubber, an ethylene-propylene-diene rubber (EPDM), or mixtures thereof, and polypropylene, which has a softening point higher than that of the reactive polypropylene, comprising at least one selected from the group consisting of random polypropylene, homopolypropylene and block polypropylene, so that the conductor has a maximum allowable temperature of 110°C to 120°C, and wherein when the conductor has a nominal cross-sectional area specified in IEC Standards 60502-2, the conductor has a maximum allowable current higher by at least 10% than a maximum allowable current calculated by Equation 1 I = Δ θ − W d 0.5 T 1 + n T 3 + T 4 RT 1 + nR 1 + λ 1 T 3 + L f ⋅ T 4 1 / 2 I: maximum allowable current of a conductor △θ: a value obtained by subtracting an atmospheric temperature from a maximum allowable temperature (°C) (a maximum allowable current of a conductor surrounded by an insulating layer made of crosslinked polyethylene is set to be 90°C, a maximum allowable current of a conductor surrounded by an insulating layer made of non-crosslinking polypropylene is set to be 110°C, and the atmospheric temperature is set to be 30°C) W d: dielectric loss per unit length of the insulating layer surrounding the conductor (W/m) T 1: thermal resistance per unit length between the conductor and the sheath layer (K.m/W) T 3: thermal resistance of the sheath layer (K.m/W) T 4: thermal resistance out of the sheath layer (K.m/W) R: AC resistance per unit length of the conductor at a maximum allowable temperature of the conductor (Ω/m) n: the number of conductors included in the cable λ 1: circuit loss factor L f: load loss factor