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Fig- 5Lamp relay set KFB 15301(right) with cover removedinsulated telephone cable (EKKX), in which 6 wires constitute the return circuit.All lamp indicators should be connected in parallel, and the cable can suitablybe drawn from indicator to indicator without having to pass through terminalboxes. The voltage drop in the circuit should not exceed 10 % at maximumload. On long circuits it might therefore be necessary to combine the EKKXcable with a heavier feed cable (EKKP).Absence IndicatorPaging signals will, of course, be of no use if the called party is away fromthe office. To avoid paging to no purpose, the system can be supplementedby absence indicator equipment. When the operator keys the number of aperson who has marked himself absent, the signal is blocked by a specialrelay set {KFB 15313) in circuit with the keyset. A signal is at the same timereturned to a time indicator panel, mounted at the switchboard, which informsthe operator of the time at which the person is expected back or that he willbe away all day. These indications are marked by the person himself on anabsence indicator panel at the main office entrance. Every person to beaccommodated on the system has his own knob on the absence indicatorpanel, which he turns to the required setting whenever he enters or leaves theoffice. The knobs are electrically connected to the relay set and to the timeindicator panel at the switchboard. The absence indicator panel accommodatesequipment for 3 1 persons.The general layout of the system is shown schematically in fig. 6.3 -IFig. 6x2200Block schematic of systems with keysetKEM 3294 and absence indicator1 keyset KEM 32942 lamp relay set KFB 153013 lamp indicators4 transformer5 absence indicator relay set KFB 153136 absence indicator panel at main entrance7 time indicator panel at switchboard6 lOOO o"o"|yy