An electrical surge protection device is structured to be installed on an electrical enclosure and to be electrically connected between one or more line conductors and one or more ground or neutral conductors. The electrical surge protection device includes a support that is structured to be installed on the electrical enclosure and a number of varistors or other electrical components that will, in the event of a voltage surge on a line conductor, shunt electrical energy from the voltage surge to the ground or neutral conductor with which it is connected. The electrical surge protection device advantageously further includes a shield apparatus that is structured to restrain an increased ambient pressure and that is electrically conductive and is electrically connected with the ground or neutral conductor.