Abstract: An arrangement for protecting devices connected to transmission lines against excess or interfering voltages resulting from lightning strokes and the action of EMP or EMI, which arrangement includes a circuit board carrying connectors for establishing connections with such transmission lines and with the devices, lightning protection chokes connected in series between the transmission line connectors and the device connectors, first excess voltage arresters connected between the transmission line connectors and the chokes for effecting coarse overvoltage protection for the devices, second excess voltage arresters connected between the device connectors and the chokes for effecting fine overvoltage protection for the devices, and a network with frequency dependent behavior connected between the device connectors and the second excess voltage arresters, and a ground conductor constituted by a large-area metal plate oriented parallel to the circuit board.