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Faults at Centrum Jan.—June 1956.Table 3Out-of-adjustment faults 71Dirty contacts 19Burnt contacts 4Sticking armatures 2Opens 16Shorts 39Leakage 4Soldering faults 13Installation faults 4Parts out of position 31Burnt-out coils or resistors 18Wear 1Defective components 22Other faults 22Total 266Faults at suburban exchanges Jan.—June 1956.Table 4Out-of-adjustment faults 39Dirty contacts 3Burnt contacts 0Sticking armatures 4Opens 10Shorts 20Leakage 1Soldering faults 3Installation faults 1Parts out of position 23Burnt-out coils or resistors 12Wear 1Defective components 5Other faults 5Total 127The time spent on maintenance, including supervisor's time, at the Centrumand suburban exchanges during the first six months of 1956 was as follows:Centrum4.229 hoursSuburban exchanges .... 2,447 »The numbers of lines at the Centrum and suburban exchanges are 20,000and 12,000 respectively. On the assumption of similar conditions during thesecond six month period, the time spent on maintenance per subscriber's lineand year would beCentrum0.43 hourSuburban exchanges 0.41 »Routine tests are still retained to a certain extent at the suburban exchanges.When this procedure is discarded, and tests are only made as required, themaintenance time at the suburban exchanges will undoubtedly be considerablyreduced.The working hours at Centrum are from 7 a.m. to 4.15 p.m. on weekdays,7 a.m. to 1 p.m. on Saturdays. The suburban exchanges are unattended.Technicians are called in the event of serious trouble outside workina hours.5