electrical continuity in the ground or ground check conductors the monitoring apparatus interrupts system power in connectors of known type which have joinder and separation directions aligned longitudinally with cables joined thereby provision is made for interrupting continuity first in the ground check conductor for this purpose there is provided a ground check line connector element having a male contact shorter in length than other male contacts and hence separable from its female contact before the separation of live and ground contacts on movement of a connector element housing fixedly supporting all male contacts connector 166 of fig1 provides for like interruption of continuity first in ground check conductor 164 and thereafter in other conductors such as 162 irrespective of the manner in which its flexible connector elements 168 and 170 are peeled from one another connector element 168 has contact strip 172 connected to conductor 162 with contacts 172a and 172b arranged successively outwardly from cable 160 in the pattern mf m for male f for female contact strip 174 is connected to conductor 164 and has contacts 174a 174d in pattern fmfm successively outwardly from cable 160 for contact strip 172 contacts 172a and 172b are each electrically connected.