On transmission line towers can be installed fiber optic cables for control of power supplies and data communication. To avoid the damages of fiber optic cables cause of the eject of climate and environment, the shielding that used on fiber optic cables was made _#am the metal. With using this shielding, the electric field that produced from transmission line will be ejected With this shielding; the electric field that produced from transmission line will be higher or lower. There for, we must know the eject of using the fiber optic cables shielding to the electric field that produced from transmission line that installed fiber optic cables. This is useful to determinating the free room from the transmission line.
