Field Experience with the Direct Buried Residential Transformer

Having made the assumption that a direct buried residential transformer was an economic necessity in unit residential installations, the next step was to determine its physical and electrical practicality. To accomplish this, it was necessary to gather engineering data. For this purpose a test installation equipped with cathodic protection and temperature test points was proposed. Installation procedures were developed to handle the field problems associated with direct burial. Methods of marking the field location were studied and the costs of converting a subsurface transformer to a direct buried unit were reviewed. Upon receiving favorable engineering data and confirmation of the anticipated economics, the direct burial concept was recognized as an acceptable approach. Now after three years of installation experience and the emergence of a direct buried transformer, methods have evolved into standards. Present installed units continue to be observed and evaluated with added interest in increased loading and multiple secondary services.