It is provided an apparatus, comprising a box configured to conduct an optical fiber from an exterior to an interior of the box; at least one of a mounting means adapted to mount a connecting means to which the optical fiber may be connected and a guiding means adapted to guide the optical fiber, wherein the at least one of the mounting means and the guiding means is arranged in the interior of the box; a detecting means arranged in the interior of the box adapted to detect a first signal from the interior of the box, wherein the first signal is at least one of a light and a smoke; wherein the interior of the box is substantially shielded from a second signal from an exterior of the box, and the detecting means is suitable to detect the second signal in a same manner as the first signal.