The analysis confirms the high efficiency of low-suspended or roof mounted horizontal air terminals. In particular, when any conducting elements in the object interior are not closer to the meshwork surface than half the length of the square mesh side, the mean value of the protection unreliability coefficient falls in the range 5×10−5 to about 10−7 (depending on the protection level). When conducting elements are placed directly below the roof surface, the protection effectiveness falls considerably. The calculated protection unreliability is strongly influenced by mean lightning parameters. Considerable discrepancy between the data in references makes it impossible to obtain unambiguous, quantitative evaluation of the efficiency of the low-suspended terminals.