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Old 04-20-2015, 06:36 PM   #15
NN5I
Carl, nn5i
 
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Join Date: Sep 2011
Location: Tallahassee, FL
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Actually it can happen to an RV with a 30-amp hookup. It depends upon where the neutral is open.

If the neutral is open, for example, at the camp's distribution panel, or somewhere between that panel and the pedestal, then the voltage at the pedestal can go wild. The reason is that the camp is wired for 120/240, with some 30-amp RVs on one side, some other 30-amp RVs on the other side, and 50-amp RVs on both. In that case, to understand it, look again at the two schematics and in your mind substitute RVs, instead of lamps, for the resistors.

Why is this worth understanding? Because, understanding it, someone may some day save his very own personal skin by testing for it before hooking up. Open neutrals in distribution panels are far from rare.
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