Fourteen Years of Data on the Operation of One Hundred Ungrounded 240-and 480-Volt Industrial Distribution Systems

A discussion is given of the data found over a fourteen-year period of 240-and 480-volt ungrounded industrial distribution system operation at Kodak Park Works, Eastman Kodak Company. An advantage of the ungrounded system over the grounded system is the higher degree of reliability that is attainable. One drawback of the system is the problem of locating a ground when it occurs. Practical and successful tracing of grounds with power on are possible and, when combined with systematic detecting and clearing, the ungrounded system may offer further advantages over the grounded system.