50A RV electrical

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  #1  
Old 05-31-07, 02:29 PM
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50A RV electrical

How can a 120/240V 50A RV plug be able to adapt to a 120V 30A receptacle? I haven't gotten inside one to see its panel, but I know my Fluke Voltage Detector shows voltage on the the single hot on the 30A side and both hots on the 50A side of the adapter. These are common adapters.

They use a NEMA 14-50 configuration for the 120/240V 50A and a non-nema 120V 30A RV-only config for the other side, the same as my 120V 30A RV, that can also be adapted to 15 or 20A 120V.

If there were no 240V loads possible, I can see it working. The adapter can put both busses in parallel. The neutral would be carrying the sum of the two hots instead of the inbalance, but it would still be limited to the single-pole 30A breaker, so that could work. When not on an adapter, the busses would be on the opposite sides of the phase, and the neutral would act normally.
 
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Old 05-31-07, 02:39 PM
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> If there were no 240V loads possible, I can see it working. The adapter
> can put both busses in parallel.

That's the only way I can see it working without a transformer. Of course you'll have to exercise smart load management to not exceed 3,600W.
 
  #3  
Old 05-31-07, 06:14 PM
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There's definitely no xformer in the loop. You can pull the plug out of a 14-50R and put it right into the adatpter and right into a 30A 120V receptacle.

As far as remembering not to overload it, you have to do the same thing with the much more common 30A to 20A adapters for the 120V campers.
 
  #4  
Old 06-01-07, 12:19 AM
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Is there a question here?

Of course the two legs of the 240/120 are paralled to work in the 120 outlet, how else would it work? And of course any 240 loads are inoperable.
 
  #5  
Old 06-01-07, 12:37 AM
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Well I guess the question was whether or not we were guessing correctly.

Glad to see it was obvious enough that we should feel stupid.

I've never owned an RV with a 50A service. I don't know if they even have 240V loads.
 
  #6  
Old 06-08-07, 01:47 PM
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MAC, you might want to ask this question on the open roads forum on rvnet, under technical issues.

this type of question is often discussed there.
 
  #7  
Old 06-08-07, 02:04 PM
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Not worth it now. Apparently, it was a dumb question and unworthy of some of the experts' times.

Guess I'll stick to industrial 3-phase.
 
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