Ques. What is a petticoat insulator?
Ans. An insulator which has one, two or three deep flanges or "petticoats" around the base for the purpose of increasing the leakage path from the line to the pin.
Both glass and porcelain insulators may be the double or triple petticoat type which may be cast or moulded solid, or made in two or more parts which are subsequently cemented together.
Service Connections and Loops.—Whenever it is necessary to tap an overhead conductor for service connection, the method of connection will depend upon the character of the circuit. In the case of a parallel circuit, an extra insulator must be placed on the cross arm so as to prevent the service main putting a side strain on the main line conductor. In the case of a series circuit the main line conductor is usually dead ended at the nearest pole and a loop taken to the point of service, as shown in [fig. 972].
Fig. 972.—Method of making a series "loop" service connection.
Fig. 973.—Parallel service connection. Service wires tapped to the main wires, are run to insulators on an auxiliary cross arm, thence to insulators on the side of the building, and through the drain tube to the service switch.