Device for protection against overvoltage with thermal disconnector with double contact surface

The device has a disconnecting unit (4) ensuring the disconnection of a varistor (3) from an electrical installation. The unit is recalled from a close configuration in which the varistor is connected to the installation to an open configuration in which the varistor is disconnected from the installation. A blocking unit (6) retains the unit (4) in the close configuration and has fusible elements, where the unit (4) has two contact surfaces secant with respect to each other. The elements adhere to the surfaces, respectively, when the unit (4) is in the close configuration. An independent claim is also included for a method of manufacturing an electrical installation protection device.