© 2005-2011 Dr. Ray Franco, PhD., PE email@example.com
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For electrical current to flow, there must be a return path back to the source. For a home, the "source" is the power company's distribution transformer. The path for the return current is normally the power company's neutral. In the event of an open neutral, the current will seek the path of least resistance. Often this is a "sneak" path through the telephone company's ground or cable TV company's ground; both of which are tied to the power company's neutral.
In the case below, the path was the cable TV company's ground. The ground of the coax cable got so hot that it melted the wire insulation. Finally, the coax cable came out of the splitter breaking the "sneak" path.
With the Neutral Open, the Return Current goes through the Braid of the Coax Cable and uses the Neighor's Neutral to return to the Transformer.
When I touched the Ground, it shocked me. With the Meter removed,
the Ground was at 115 VAC with Respect to the Gas Pipe. (F08-023).
References: 1. 2008 Edition NFPA 921, "Guid for Fire & Explosion Investigators", Section 8.5.2.