§ 81. Mr. Harold Walker
asked the Postmaster-General what is the effective life of a telephone exchange with regard to its equipment; and how many exchanges now in service are older than that.
§ Mr. Benn
The effective life of telephone exchange equipment depends on a number of things. For instance the amount of use made of the equipment, the atmospheric conditions, the technical design and the facilities it provides. In genera], 30 years is regarded as the average effective life and this figure is taken for capital depreciation. About 250 automatic exchanges out of a total of 5,500 have some equipment over 30 years old.