Dave Solberg is a leading expert in the RV industry and author of the “RV Handbook” as well as the Managing Editor of the RV Repair Club. Today he discusses dogbone adapters and circuit breakers.
I have the 50-amp to 15-amp adapter which my dealer sold me. I run a good-sized 100′ extension cord from the adapter to my regular garage outlet (standard 110v outlet) that is on a 20-amp circuit. With this configuration, only half of my distribution panel works in the RV. That half has no outlets in the RV energized on it (including the refrigerator, microwave, TV) and the two batteries for the 5th wheel will NOT charge (but the A/C over the bed will work and the washer-dryer plug).
I use the 50-amp shore cord provided by Mesa Ridge (Jayco) with an adapter to a 30-amp cord, and another adapter from the 30-amp cord to a 15-amp male. I plug the same extension cord into the 15-amp adapter, then into the same outlet in my garage. Like presto magic, everything is energized in the RV including the refrigerator, TV, Micro and the batteries will now charge!!
My electrician was puzzled by this.
He said the only remedy would be to swap the two main electric wires coming into the distribution panel, so the half with the outlets (refrigerator, batteries, etc.) will work. I called my dealer and checked on the Mesa Ridge/Highland Ridge owners forum and everyone said the same thing; the 50-amp adapter to 15-amp should energize both sides.
I am really confused. I have tried two different brand 50-amp to 15-amp adapters, different extension cords and other outlets all with the same result. Also, I replaced the GFCI in the RV thinking that was the problem.
This is my first 5th wheel and my first 50 amp. My travel trailer had a 30 amp. I used an adapter straight off the trailer with no problem. My trailer is out in front of my house. —Gena
(Gena and I have talked several times since this first question came my way and we were able to get a little more information, as this was something new to me, as well.)
First, the 50-amp power cord has two “hot” wires that supply 120-volt power to each breaker in the distribution center.
Two-poled circuit breaker
Notice the “AC In Hot 1” and “AC In Hot 2” in the red square with the wire from each going to the representing circuit breaker circled in red. These circuit breakers are two-poled, which means there is a bar going across the tabs so if one side trips, they both trip.
However, when using a “dogbone” that reduces from 50 amp to 15 amp, like you suggested, it eliminates one hot side and only provides one to the “AC In Hot 1” side—therefore your issue with only half the panel working.
Note: I would never suggest using this type of extension cord without verifying it is at least 15 amps or more!
Distribution center has two breakers
I verified with Dennis from Progressive Dynamics that their 50-amp distribution center has the two breakers, and if you are using the typical “dogbone” reducer/adapter it will only power one side.
So, why does the 50-30-15 configuration work? After doing research and getting a close up photo of what Gena was using, we can see the 50-30 amp reducer has a “jumper” wire that provides power to both L1 and L2 of the 50-amp plug going to the coach!
This configuration will work; however, it requires leaving two expensive cords out in the open, the 50 amp and the 15 amp, plus creates a cord length that is dangerously long. It is best not to go past 50 feet if possible and use the correct gauge wire/cord. A 50-amp cord is 6 gauge, 30-amp is 10.
Note: Much better 15-amp extension cord!
After more research and talking first with Jim at Northern Wholesale Supply, who referred me to Brad at Park Power, he suggested the model 1550 ARV, which plugs into the side of the rig. Your 15-amp extension cord can go straight to that.
According to Brad, this adapter will split the power to both wires on the 50-amp plug and therefore supply power to both circuit breakers. Keep in mind it will only provide 15 amps total, so you are very limited to what can be run. Do not run the roof air conditioners as they can draw up to 14 amps each. The refrigerator will draw 8-9 amps and will also draw 12-volt power from the house batteries which in turn will kick in the converter or inverter/charger that will draw another 8-9 amps. I would suggest getting a Kill A Watt® meter and plugging it into your outlet, then plug in the extension cord to see what you are actually drawing.
Also, make sure the outlet you are plugging into is not “ganged” with any other outlet and the cord is not too long so as to create a power drop. In my opinion, it is best to install a dedicated 30-amp circuit for your rig if possible.
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