Electrical device against transient overvoltages comprising: ∘ a housing intended to receive a varistor device for detecting thermal runaway comprising at least one set of varistors comprising a first varistor and a second varistor, - a first electrical junction terminal intended to be connected independently to a power grid or to the ground, comprising: ∘ a first movable contact arm (A120a) extending in the housing in an initial position to be in contact with a first electrical connecting terminal of the first varistor, ∘ a second movable contact arm (A120b) extending in the housing in an initial position to be in contact with a first electrical connecting terminal of the second varistor, - a thermal protection device characterized in that it comprises: ∘ a first trip zone intended to be tripped when a sealing of a first thermal detector of the varistor set is unsealed, to cause the displacement of the first movable contact arm (A120a) from the initial position to a disconnected position wherein the first movable contact arm is intended to disconnect from the first connecting terminal of the first varistor, ∘ a second trip zone different from the first trip zone, able to be tripped, when the sealing of the second thermal detector is unsealed, to cause the displacement of the second movable contact arm (A120b) in a disconnected position wherein the second movable contact arm is intended to disconnect from the first electrical connecting terminal of the second varistor, oin which each trip zone is dissociated from the electrical connecting terminal of each varistor. ∘ a housing intended to receive a varistor device for detecting thermal runaway comprising at least one set of varistors comprising a first varistor and a second varistor, - a first electrical junction terminal intended to be connected independently to a power grid or to the ground, comprising: ∘ a first movable contact arm (A120a) extending in the housing in an initial position to be in contact with a first electrical connecting terminal of the first varistor, ∘ a second movable contact arm (A120b) extending in the housing in an initial position to be in contact with a first electrical connecting terminal of the second varistor, ∘ a first movable contact arm (A120a) extending in the housing in an initial position to be in contact with a first electrical connecting terminal of the first varistor, ∘ a second movable contact arm (A120b) extending in the housing in an initial position to be in contact with a first electrical connecting terminal of the second varistor, - a thermal protection device characterized in that it comprises: ∘ a first trip zone intended to be tripped when a sealing of a first thermal detector of the varistor set is unsealed, to cause the displacement of the first movable contact arm (A120a) from the initial position to a disconnected position wherein the first movable contact arm is intended to disconnect from the first connecting terminal of the first varistor, ∘ a second trip zone different from the first trip zone, able to be tripped, when the sealing of the second thermal detector is unsealed, to cause the displacement of the second movable contact arm (A120b) in a disconnected position wherein the second movable contact arm is intended to disconnect from the first electrical connecting terminal of the second varistor, oin which each trip zone is dissociated from the electrical connecting terminal of each varistor. ∘ a first trip zone intended to be tripped when a sealing of a first thermal detector of the varistor set is unsealed, to cause the displacement of the first movable contact arm (A120a) from the initial position to a disconnected position wherein the first movable contact arm is intended to disconnect from the first connecting terminal of the first varistor, ∘ a second trip zone different from the first trip zone, able to be tripped, when the sealing of the second thermal detector is unsealed, to cause the displacement of the second movable contact arm (A120b) in a disconnected position wherein the second movable contact arm is intended to disconnect from the first electrical connecting terminal of the second varistor, oin which each trip zone is dissociated from the electrical connecting terminal of each varistor.