With the purpose of designing methods to clearly identify which plant species generate electrical ground discharges in energy transmission line service corridors and thus avoid the frequent pruning of all vegetation present In the corridors, this study proposes and evaluates “compatibility” index of plant species with transmission lines, based on six variables: maximum height, growth form, ecological group, life zone, and abundance and frequency of each species. This index was tested in 20 plots of 200 m2 in three life zones influenced by the national electrical transmission system, in which information was collected on all vascular plants present, yielding 2147 Individuals belonging to 485 species and 105 families. The most discriminating variables in the model were life zone and ecological group, based upon an Analysis of Principal Components. This index applied to the 147 fully identified species with DBH = 2,5 cm showed that Cecropia peltata and Jacaranda copaia were the most problematic species for service lines. Furthermore, a catalogue was developed containing general information and a photographic record of some of the species considered as compatible as a reference for use during maintenance work.