Design data in rural distribution lines

The available data relating to the detail design of rural distribution lines are very limited and scattered, and only to be found by prolonged search through numerous technical journals, manufacturers´ lists, and the usual textbooks. They refer primarily to individual fittings, or alternatively to basic principles. Although the principles involved are in the main simple, the calculations are often in their practical application lengthy and tedious. All overhead transmission or distribution lines in this country must be designed to comply with the Regulations for Overhead Lines El. C. 53, prescribed by the Electricity Commissioners for securing the safety of the public. Thebasic factors of design are therefore common to various types of construction, even though the detail design may vary considerably. The prime purpose of this paper is to present information relating to the detail design of overhead lines for rural distribution, in a form which it is hoped may prove easy of application, and thus obviate many of the tedious calculations above referred to. An attempt has been made to simplify and clarify the application of basic principles by means of a series of tables and graphs, which enable one to determine at a glance the final results, in much the same way as the complexities of the properties of steam have been clarified in the entropy diagram, or the effect of money rates operating over a number of years, as readily seen in interest or discount tables. The form of presentation of much of the data is originaland no attempt has been made to include the usually accepted formulae or fundamental principles, details of which may be found in any reliable textbook. Similarly, details of the official regulations relating to overhead lines are not included, as they are covered in the Electricity Commissioners´ Regulations El. C. 53 and Explanatory Memorandum El. C. 53A. The paper is divided into two parts, the first being a series of tables and graphs covering various- aspects of line design, the second describing a number of practical details of design which have proved efficient in service. It is hoped that the form of presentation may appeal to the busy engineer, and in particular to those who may be responsible for the design and erection of both high and low-voltage overhead distribution lines.