The injurious effect of stray railway current has been a problem to utilities for many years, particularly to the gas distribution systems having electric railways crossing through or bordering their territory. The necessity for proper control of these vagabond currents is very important. This is particularly true at locations where the underground structure becomes positive to the DC negative. The complexities of a gas distribution system in a stray current area are multifold, as the system is usually crosstied to the water system as well as having stub ends, high resistant joints, and other grounds. The piping often is of diverse ages, sizes, and coating conditions which add to the problem.
Up until a few years back, there were only a few devices that were available for installation for proper control of stray currents. Such instruments were not reliable as maintenance and constant inspection were expensive. The older switches did...
