This paper reviews the test methods and results of an investigation of several explosions on an industrial oxygen piping system. Suspected causes of the explosions included interference from overhead HVAC power lines, phase-to-ground fault currents, and lightning strikes both on the power lines and on above ground piping appurtenances. Investigative procedures included computer modeling of the power line grounding system, measurements of grounding grid effectiveness, and induced AC testing. Keywords: underground, pipeline, piping, oxygen, explosion, induced AC, grounding, isolation, lightning