. Mechanical Contracting & Plumbing January-December 1909. ch are in contact with the ground,through the ground and such metallicconstructions in it as offer the least re-sistance to the flow, and after flowingthrough these (gas pipes, water mains,lead-covered cables, etc.) towards thestation, will return through the ground,back to the rails to return conductors inthe vicinity of the power house. Thesestray currents cause electrolytic action,that is, wherever current passes from apipe or cable to ground, or to another pipe or cable, corrosion of the metal isset up; holes and pittings are produ
. Mechanical Contracting & Plumbing January-December 1909. ch are in contact with the ground,through the ground and such metallicconstructions in it as offer the least re-sistance to the flow, and after flowingthrough these (gas pipes, water mains,lead-covered cables, etc.) towards thestation, will return through the ground,back to the rails to return conductors inthe vicinity of the power house. Thesestray currents cause electrolytic action,that is, wherever current passes from apipe or cable to ground, or to another pipe or cable, corrosion of the metal isset up; holes and pittings are produced,causing bursting and leaking of pipes,eating away of the lead-covering on tele-phone and other cables, rendering themuseless. This corrosion may be veryrapid and depends on the intensity of thestray currents passing through. If the rails in a track system werecontinuous and the current density inthe rails kept low, with rails well con-nected to the power house, the railswould offer such a good return path forthe current that street piping, cables and. Electrolysis of City Water Mains. other metallic structures would he prac-tically immune from electrolytic damagedue to stray currents. However, as therails are not continuous but made up inlengths, they must be jointed by copperbonds possessing such mechanical andelectrical properties as will secure per-manent and efficient electrical continuityof the rails between sections. If suchbonding does not exist, and if returnfeeders connecting the rails to the powerhouse are inadequate for the purpose, theamount of leakage current must be greatand electrolysis is bound to exist. Theimmunity of street piping and other met-allic structure from electroyltic damagedue to stray currents demands that eleo- 19 trie railway companies adopt such meth-od of construction for their track returnsas will minimize the danger and the rail-way companies must maintain the effici-ency of such construction through sys-tematic inspection and repair. In
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