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Canadian_Rainbi's avatar
Jan 20, 2017

UPDATE Splicing 30A plug to 50 amp cord

First of all, don't tell me to buy a new 50A plug. We are in southern Mexico and there are none to be had.

On Amazon US I have seen them for under $20.00. On Amazon Canada the Camco 55255 Power Grip was $87.59 plus $26 shipping IN CANADA! :E

A friend in the park here has a relative flying down in a couple of weeks from Montreal. However I am NOT going to pay that kind of $$$ I am waiting to hear back from a Canadian RV shop, but she leaving for a few weeks. If the plug goes up in smoke I will have to do something. Need the AC here in the 30+C temps.

Here is the problem; The 50 Amp plug on the shore power cord AND the receptacle on the 50-30 amp dog bone adaptor are hot when running the air. The plug on the 50 A cord is showing signs of extended heating--rubber pulled away slightly from the metal prongs on both hots and the neutral. The U ground is OK. The 50A cord is hot only for the foot or two nearest the plug. With the AC running the plug reaches 100F, the 50A cord a foot away is 82 or so and several feet further is at 77 which at the moment is ambient. All cords and plugs are in the shade of a high brick building and never see the sun.

I tried cleaning the plug contacts to shinny brass and using a brand new dog bone adaptor with little change.

What I want to do is cut off the male 50A plug from the cord and the 50A receptacle from the dog bone and splice the remaining part together essentially, putting a three wire 30A plug on the 4 wire 50A cord. When we get up into the USA on our way home. I'll buy a new plug and socket and wire thing back correctly. There won't be many RV parks down here with 50A outlets anyway.

So here is the question: Do I splice the red and black from the 50A to the black on the 30A OR do I just not connect the red?

I am reasonably competent electrically, having completely wired the sub panels and branch circuits for both my work shop and ham radio shack and both passed the Electrical Inspectors eyes.

I have my soldering gun and tools with me--No self respecting Ham would RV without them :B, and will solder and heat shrink the connections.
  • Canadian Rainbirds wrote:

    So here is the question: Do I splice the red and black from the 50A to the black on the 30A OR do I just not connect the red?

    If you splice them together, then (in theory) you could pull 100A @ 120V. Hopefully the breaker at the monument won't let that happen.

    If you don't splice the 2, some of your AC circuit will be dead and your second A/C unit will not operate.
  • Yes splice both the red and black from the 50 amp cable to the black wire on the 30 amp cutoff adapter
    White on white
    Green on green
    That's what the adapter does internally

    I would suggest fridge on l.p. And water heater off or l.p.
    Batteries should be charged so A/C should be only load
  • Very simple
    Duplicate what the adapter does.
    Get your meter out and measure which on 50 side is 30 on the other.
  • yes- red and black tied together, but.... that 50 amp plug is nothing special to RVs- it's a commonly used one.
  • Both L1 and L2 wires (black and red hots) to the hot side (brass side)of the 30a plug.
    Then Neutral to Neutral and Ground to Ground.

    You may have trouble getting one and especially two #6 wires properly attached to the terminals in the plug. May need a box to reduce the wires to #10. I think I would get a new adapter or home make an adapter over lopping off the 50a plug.

    Plug may still get hot and melt. Try to reduce your load with less electric and more propane.
  • Assuming the red and black on the 50 amp side are the two hots (which they should be), then yes, just splice them together and connect to the one hot from the 30 amp side. If you did not connect the red, you would be missing power to half of your 120 vac circuit breakers in the RV.

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