PUP 50Amp upgrade?

Discussion in 'Power - Site Power/Batteries/Generators/Solar' started by DJO-PUPNEWBIE, Nov 11, 2018.

  1. SteveP

    SteveP Well-Known Member

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    Unless you're currently popping the 30 amp breaker in the campsite panel you could possibly meet your needs by adding an additional 15 amp breaker to the current panel in your pup and wiring one of the existing outlets directly to the new breaker.
     
  2. Toedtoes

    Toedtoes Well-Known Member

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    Perfectly legal. Folks plug their 30amp RVs into 50amp pedestals all the time because the 50 amp outlet is usually newer. You know how much power you can pull on 30 amps, so you just keep your usage there and you're fine.
     
  3. tombiasi

    tombiasi Well-Known Member

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    Then the main would be 100 Amps. You are only going to get what the breaker is rated for no matter how you take it.
     
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  4. Toedtoes

    Toedtoes Well-Known Member

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    You only get 50 amps.

    Most RVs are wired to use both sides (legs) of the 50 amp connection separately. In the RV, the system is split in half - with half the electrical power pulling from one leg and the other half pulling from the other leg. So, while you can power 50amps through each leg, you cannot combine those to pull a single 100 amps through half the system.

    There are a few new high end rigs that are set up for 50amp at 240v, but they are not common.
     
  5. BillyMc

    BillyMc Well-Known Member

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    The quickest cheapest way I've found to solve the need more power thing is connect the AC or space heater to a separate 20amp cord plugged into the 20amp outlet on the campsite hookup. Then use the current 20amp circuit to add some new outlets.
     
  6. tombiasi

    tombiasi Well-Known Member

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    You could show mathematically that the two legs are 180 degrees out of phase and the main supply would never see both legs at the same time. So much for math. One cannot design on reliance of the phase difference since the calculations would only be true with resistive loads or compensated loads and cannot be used in design.
     
  7. Balthisar

    Balthisar Active Member

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    You don't have to show anything mathematically. It's a split-phase, single-phase electrical system, just like we all have in our houses. These are 240 VAC circuits at 50 amps. You don't need 100 amp main breaker because it's not 100 amps. It's only 50 amps, at 240 VAC. You get 50 amps per leg, or 100 amps total at 120 VAC.

    Toedtoes is correct in saying you don't get 100 amps for any single device, but you have 50 amps + 50 amps = 100 amps available for multiple devices.
     
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  8. 1380ken

    1380ken Well-Known Member

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    Yes, math is useless.
     
  9. tombiasi

    tombiasi Well-Known Member

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    I never said or implied that.
     
  10. Toedtoes

    Toedtoes Well-Known Member

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    I think we've gone way beyond the subject of the thread - converting a 30amp system into a 50 amp system. ;)
     
  11. tombiasi

    tombiasi Well-Known Member

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    How would the circuit know if the load was from multiple devices or a single device? You don't have 50 amps "+" 50 amps you have 50 amps "or" 50 amps.
     
  12. 1380ken

    1380ken Well-Known Member

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    If you go look at your house fuse box. If you have any 220v device in your house like a stove or dryer. Look at the breaker. A 50 amp 220 volt breaker is really two 50amp 110 volt breakers. Two 50 amp 110v beakers out of phase equals a 220 volt 50 amp breaker. A typical house will have a 100 amp 220 volt service. Which is actually a 200 amp 110 volt service.
     
  13. Toedtoes

    Toedtoes Well-Known Member

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    A 50amp pedestal has one outlet for that breaker. The outlet has 4 holes: ground, neutral, hot and hot. Each hot is 50amps at 110v.

    The 50amp RV has a plug with 4 prongs: ground, neutral, hot, hot. Each hot is 50amps at 110v.

    The RV plug connects into the RV as 2 separate systems, each 50amp at 110v. If you look at the wiring, you will see that the electrical items are split. Usually, if there are 2 AC units, each will be on a separate system. The bedroom may be on the 1st system, the living room on the 2nd, the bathroom on the 1st, etc. Each system has a master breaker for the full 50amps. Within that, there will be smaller breakers that apply to various outlets, AC unit, water pump, etc.

    Regardless of how many items you plug into one system, it *will not* pull more than 50amps at 110v from the pedestal. Because the pedestal has a 50amp at 110v breaker for each leg (hot wire). If you plug in one item that requires 100amps, or you put several items on one leg that require 100amps total, the pedestal's breaker will trip. You can put one item, or several items, totalling up to 50amps on each leg. In addition, the RV's breakers will trip if you try to pull more than 50amps through either leg.

    Similar to at home: you have two outlets on separate breakers - you can pull up to 15/20amps from each outlet, but you cannot pull 30/40amps from either.

    Note: I say *will not* because I don't want to have someone argue about a power surge, etc. This is about the standard pull, not stuff like that.
     
  14. Balthisar

    Balthisar Active Member

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    Circuits don't know anything. You can have load(s) totaling 50 amps on one leg, and load(s) totaling 50 amps on the other leg, for a total load of 100 amps, i.e., 50 + 50, and not only 50 or 50. (Usual disclaimer about ideal circuits, no inductive reactance, breakers that don't heat up too fast, inrush current, etc.)

    Toedtoes provided a spot-on explanation.
     
  15. tombiasi

    tombiasi Well-Known Member

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    I give up. Please get back when you can draw 100 amps from a 50 amp pedistal.
     
  16. Toedtoes

    Toedtoes Well-Known Member

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    I think we're getting lost in semantics.

    You aren't pulling 100amps out of a 50amp outlet. You don't have 100amps.

    You do have two legs at 50amps each. You can only pull 50amps from each leg.

    What the 50amp outlet does is allow you to pull 50amps from one leg and 50amps from the other at the same time. Which is not the same as pulling 100amps.
     
  17. Matt Benoit

    Matt Benoit Well-Known Member

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    I think you're all getting lost on the OPs original post. Lol
     
  18. GreyFox

    GreyFox Well-Known Member

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    Well since we're now splitting hairs the nominal voltage of an unloaded source supply in both Canada and the US is 120 vac @ 60 Hz, not 110 vac, and an unloaded 50 amp RV service will measure 240 vac @ 60 Hz between the 2 hot legs, not 220 vac, also as many keep erroneously repeating. :wink:
     
  19. 1380ken

    1380ken Well-Known Member

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    220 221
     
  20. rabird

    rabird Howdy!

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    Back, 50A service can deliver up to 12,000 watts, that is 100A @ 120v. 6,000w per leg.
    The neutral is only as big as each hot cuz if both legs are being used the same there is no current on the neutral.
     

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