習知由直流電車系統的漏電對地下管道有可能會產生電性腐蝕（電蝕），爲防範電蝕首先須對其洩漏電流，洩漏電阻有十分的資訊。這資訊並不可能由理論推導而必須根據實測而來。以往對這些電流或電阻值的測試吾人並無經驗，筆者於本文裡參考國外的經驗與資料加以分析，檢討其可行性，並儘可能列出如要在台灣實測時的可能需要的實際電路與數據供參考。

The leakage current from dc electric train to undergrourd metalic conduits might introduce serious corrosion problems. For the purpose of preventing corrosion problems, the leakage impedance from grounded rail to earth should be estimated. This impedance could not get from theoretical calculation. Unfortunately, up to now we have very few experiences of such measurements. In this paper, I will introduce a measuring method proposed in the literature.