Isolation of Trolley Bus Negative Return To Prevent Stray Current Corrosion^★

When a rail transportation system is converted to trolley bus operation, there is a tendency to continue the use of rails for negative return. In two Ohio cities—Akron and Youngstown—where this was done, the resultant problems, corrosion and otherwise, finally led to abandonment of rail return and isolation of the negative return from ground.

The experience in these cities is reported from the standpoint of two utilities, Ohio Edison Company and The Ohio Bell Telephone Company, whose underground structures were involved. This paper compares corrosion conditions before and after the isolation. The problems which arose during the conversion and those which became apparent after the isolation are discussed.