Why is a mobile home any different than any other dwelling?
The answer to your question is contained in the definition of a mobile home that is found in the US NEC.
"Mobile Home. A factory-assembled structure or structures transportable in one or more sections that is built on a permanent chassis and designed to be used as a dwelling without a permanent foundation where connected to the required utilities and that includes the plumbing, heating, air-conditioning, and electric systems contained therein." Copyright 2002 The National Fire Protection Association
It is the permanent chassis that makes these buildings unique because that chassis serves as an equipotential plane under the mobile home. The equipotential plane will be at ground potential if the unit is properly installed. If any fault occurs in the wiring of a mobile home the chassis is likely to distribute that stray voltage and current over the entire shell and many of the fixtures and appliances of the mobile home. That characteristic is unique among dwelling places to mobile homes. The consequences of a wiring fault being so much more likely to result in electrical shock to persons living in or visiting a mobile home justifies the additional precautions required by the US NEC.
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Tom H
