This report study the possibility of monitoring the condition of the link boxes in a cross bonded cable line. The study is focused on how the condition can be determined from an impedance measurement, in order to make the method available, line impedance measuring equipment is used. The measuring technique is improved to gain high sensitivity in respect
to screen circuit faults. This is achieved, using ungrounded voltages sources and increased measuring frequency. A DIgSILENT simulation model of the cable line FRT-NOR is developed and verified against field measurements. The simulation model is used for simulation of four study cases, which represent possible link
box faults. From the study cases the largest detectable fault resistances are determined to 39-68 Ohm according to the type of fault. Finally there are given suggestions of how the impedance method could be used at cable lines consisting of more than one major section. It is recommended to make strategic chosen link boxes easy accessible, when construction new cable lines.