Abstract: A surge protective device (SPD) module includes a module housing, first and second module electrical terminals mounted on the module housing, a gas discharge tube (GDT) mounted in the module housing, and a fail-safe mechanism mounted in the module housing. The GDT includes a first GDT terminal electrically connected to the first module electrical terminal and a second GDT terminal electrically connected to the second module electrical terminal. The fail-safe mechanism includes: an electrically conductive shorting bar positioned in a ready position and repositionable to a shorting position; a biasing member applying a biasing load to the shorting bar to direct the shorting bar from the ready position to the shorting position; and a meltable member. The meltable member maintains the shorting bar in the ready position and melts in response to a prescribed temperature to permit the shorting bar to transition from the ready position to the shorting position under the biasing load of the biasing member.