Critical inside dimensions for power cable manholes

The three basic approaches to manhole design are: duplication of existing design; modification of existing design to eliminate certain known defects or inadequacies; and new design based on recently developed methods of predicting cable sheath life. This paper deals primarily with the latter, but it is well to keep in mind that existing design has been given a field test, whether formal or informal, and that the lessons learned from experience are extremely valuable. Since manholes and allied underground structures are of so many different sizes and shapes depending on the purpose which they serve, it has been necessary to limit the scope of this paper to power cable manholes and in particular, to the manholes along the route of transmission or express circuit cable lines.