Method for detecting line faults in a hazard detection system, in particular having a detector line which connects a plurality of detectors (8, 11) via a connecting line, the detectors (8, 11) comprising, in particular, a switch for connecting or disconnecting the connecting lines, which switch can be used to connect through a supply voltage to a further detector, having the following method steps of: a. applying a supply voltage from a voltage source to a first detector (8, 11), the switch of which is open, b. measuring a first terminal voltage (U 1) in the first detector (8, 11) during a time in which the detector loads the voltage source with its quiescent current (I 1), c. loading the voltage source with an increased defined current (I 2) by means of the detector (8, 11) and simultaneously measuring a second terminal voltage (U 2) in the first detector (8, 11), d. determining a comparison voltage (U min) from the first and second terminal voltages (U 1, U 2), the current difference (I 2 -I 1) and a maximum inrush current (I max) which is assumed to be known, e. closing the switch in the first detector (8, 11), as a result of which the voltage applied to the first detector (8, 11) is connected through to the next section of the connecting lines and the supply voltage is therefore applied to a second/further detector, in particular, f. measuring a third terminal voltage (U 3) in the first detector (8, 11) after the switch in the first detector (8, 11) has been closed, g. comparing the third terminal voltage (U 3) with the comparison voltage (U min) determined in step d., h. opening the previously (in step e) closed switch if the third terminal voltage (U 3) falls below the comparison voltage, or repeating steps b to h with each further available detector (8, 11), the second/further detector then assuming the function of the previously first detector (8, 11). a. applying a supply voltage from a voltage source to a first detector (8, 11), the switch of which is open, b. measuring a first terminal voltage (U 1) in the first detector (8, 11) during a time in which the detector loads the voltage source with its quiescent current (I 1), c. loading the voltage source with an increased defined current (I 2) by means of the detector (8, 11) and simultaneously measuring a second terminal voltage (U 2) in the first detector (8, 11), d. determining a comparison voltage (U min) from the first and second terminal voltages (U 1, U 2), the current difference (I 2 -I 1) and a maximum inrush current (I max) which is assumed to be known, e. closing the switch in the first detector (8, 11), as a result of which the voltage applied to the first detector (8, 11) is connected through to the next section of the connecting lines and the supply voltage is therefore applied to a second/further detector, in particular, f. measuring a third terminal voltage (U 3) in the first detector (8, 11) after the switch in the first detector (8, 11) has been closed, g. comparing the third terminal voltage (U 3) with the comparison voltage (U min) determined in step d., h. opening the previously (in step e) closed switch if the third terminal voltage (U 3) falls below the comparison voltage, or repeating steps b to h with each further available detector (8, 11), the second/further detector then assuming the function of the previously first detector (8, 11).