The possibility of a correct account of the fine structure was shown for two limiting cases observed in beam and plasma experiments. A significant difference was found in the emission cross sections and the rate coefficients of direct and dissociative excitation of the and H_α and H _β lines by electron impact in two limiting cases (e.g., this difference reaches an order of magnitude for dissociative excitation of the H_β line). The most reliable data on the cross sections and the rate coefficients of direct and dissociative excitation of the H _α and H_β lines by electron impact were found for both limiting cases. It was shown that, among the first four lines of Balmer series (rather easily detected), only the first two lines, i.e., H _α and H_β, can be currently employed in plasma spectroscopy studies because of the absence of data on the partial excitation cross sections of hydrogen atom nl-sublevels with n ≥ 5.