Th e present work aims at developing a meth od-Jar the first time-for assesBing Ow decide jield around a chmyed conduct or posit ioned in air (oJ zero conduc tivity) at a .'liven height above a two-layer earth. The method is based on the com plex su ccessine imaging technique, being a quasi-static approximation fo r estimating the potent ial due to a lin e charge above the eart h. With the knowledge of the image charges , th e electric field uolues in air and earth are (l8ses,"w,d. A luboratoq) trans mission- line model and an electrolytic -t ank model tsere cons tructed to simulate three-phase and single-phase transmission lines above a two-layer earth. The measured electric field s agreed reasonably with those calcula ted fo r one- and two-layer earth models. Th e calculation method is extended for assessing electric fields in power substa tion» as injluenccd by earth modeling in one or two layers.