30 amp 240 volt mistake!!

[mxdad777]

I recently bought a 2018 Rockwood 5th wheel with a 50 amp service. I have a 240 v 50 amp outlet in my RV cover that I’ve used for years to plug my motorhome into. Since I still have my motorhome and it’s parked in the RV garage I decided to hook up my 5er temporarily to my 30 amp 240 volt welder outlet. I had no idea that RV 30 amp cords were 120v only. Long story short, after connecting my 30 to 50 adapter I sent 240 volts down one leg of the buss bar. So everything on that side of the bus bar received 240 volts while the other side received zero. My question now is what will I need to replace? My refrigerator, GFCI, rooftop A/C were all on that side. The A/C seems to be working fine, but the fridge isn’t and the GFCI is smoked. Although I’ve wired up many homes, I certainly learned something about RV’a and their wiring today. I’m hoping just the circuit board on the fridge can be replaced. Anyone else have any experience with this? I’m sure this can’t be the first time this has happened. Stupid me!!

[westernrvparkow]

cavie wrote:

mxdad777 wrote:

BB_TX wrote:
If you used a standard 50/30 dogbone adapter be aware that the adapter connects both hot legs of the coach together. Meaning you put 240 on both hot legs, not just one.

That’s what I used, however when I tested both buss bars only one had 240v. The other bar was dead.

You did not have 240 on 1 buss bar, you had 120 on the buss bar and 120 on the neutral. 240 between hot and neutral.

You are new to these forums. You will soon discover that with all the misinformation about electrical service it is a wonder that natural selection hasn't cleaned out the well meaning, but erroneous posters. You are absolutely correct in your diagnosis, but it will be lost in a sea of erroneous posts.

[BB_TX]

cavie wrote:

BB_TX wrote:
If you used a standard 50/30 dogbone adapter be aware that the adapter connects both hot legs of the coach together. Meaning you put 240 on both hot legs, not just one.

You can not put 240 volts down both legs. A 30/50 adaptor takes the one 30 amp 120 volt leg and puts that 120 volt leg on the 2 120 volts legs of the 50 amp cord. 120 volts @ 30 amps down both legs.

A 50/30 adaptor takes just 1 50 amp leg and put in down the 1 hotleg of a 30 amp cord.

you can not get 240 volts on one leg of a service in the US and Canada. That only happens in european countries.

An adapter to connect a 50 amp RV to a standard 30 amp outlet connects the 30 amp hot leg to BOTH of the 50 amp RV hot legs. The two hot legs are connected internally in the adapter. Otherwise if you connected a 50 amp RV to a park 30 amp outlet you would only have 120 vac to half the RV. And that just ain’t how it works. And that type adapter is what he said he used. I said 50/30. Thank you for the correction to 30/50.

[cavie]

mxdad777 wrote:
I changed the welder receptacle to one that would fit my RV. My mistake was thinking both the 30amp and 50amp RV outlets were both 240v. I knew everything in the RV ran off of 120v, but figured it was the same configuration for both 30 and 50. When I tested the buss bars in the panel, I indeed had 240v on one leg and zero volts on the other. I checked the glass fuse on the fridge circuit board and unfortunately the fuse is good. My guess is the circuit board is toast. Since the microwave and AC unit seem to be working fine, I’m hopeful the only damage was to the fridge. I think my converter should be fine, because it’s fed off the buss bar that had zero power going to it.

Your gonna fix the welder outlet like it was RIGHT!

[cavie]

mxdad777 wrote:
I changed the welder receptacle to one that would fit my RV. My mistake was thinking both the 30amp and 50amp RV outlets were both 240v. I knew everything in the RV ran off of 120v, but figured it was the same configuration for both 30 and 50. When I tested the buss bars in the panel, I indeed had 240v on one leg and zero volts on the other. I checked the glass fuse on the fridge circuit board and unfortunately the fuse is good. My guess is the circuit board is toast. Since the microwave and AC unit seem to be working fine, I’m hopeful the only damage was to the fridge. I think my converter should be fine, because it’s fed off the buss bar that had zero power going to it.

You did not have 240 one leg. You had 120 on one leg and 120 on the neutrals.

[cavie]

mxdad777 wrote:

BB_TX wrote:
If you used a standard 50/30 dogbone adapter be aware that the adapter connects both hot legs of the coach together. Meaning you put 240 on both hot legs, not just one.

That’s what I used, however when I tested both buss bars only one had 240v. The other bar was dead.

You did not have 240 on 1 buss bar, you had 120 on the buss bar and 120 on the neutral. 240 between hot and neutral.

[DougE]

Scary reading. A lot of ignorance here! A 240v fully wired outlet is 120v, 120v, neutral, ground (4 wires). From there you can drop down to pretty much anything you want with the correct adapters.

[cavie]

BB_TX wrote:
If you used a standard 50/30 dogbone adapter be aware that the adapter connects both hot legs of the coach together. Meaning you put 240 on both hot legs, not just one.

You can not put 240 volts down both legs. A 30/50 adaptor takes the one 30 amp 120 volt leg and puts that 120 volt leg on the 2 120 volts legs of the 50 amp cord. 120 volts @ 30 amps down both legs.

A 50/30 adaptor takes just 1 50 amp leg and put in down the 1 hotleg of a 30 amp cord.

you can not get 240 volts on one leg of a service in the US and Canada. That only happens in european countries.

[mxdad777]

BB_TX wrote:
If you used a standard 50/30 dogbone adapter be aware that the adapter connects both hot legs of the coach together. Meaning you put 240 on both hot legs, not just one.

That’s what I used, however when I tested both buss bars only one had 240v. The other bar was dead.

[mxdad777]

I changed the welder receptacle to one that would fit my RV. My mistake was thinking both the 30amp and 50amp RV outlets were both 240v. I knew everything in the RV ran off of 120v, but figured it was the same configuration for both 30 and 50. When I tested the buss bars in the panel, I indeed had 240v on one leg and zero volts on the other. I checked the glass fuse on the fridge circuit board and unfortunately the fuse is good. My guess is the circuit board is toast. Since the microwave and AC unit seem to be working fine, I’m hopeful the only damage was to the fridge. I think my converter should be fine, because it’s fed off the buss bar that had zero power going to it.

[BB_TX]

If you used a standard 50/30 dogbone adapter be aware that the adapter connects both hot legs of the coach together. Meaning you put 240 on both hot legs, not just one.

[cavie]

mxdad777 wrote:
I recently bought a 2018 Rockwood 5th wheel with a 50 amp service. I have a 240 v 50 amp outlet in my RV cover that I’ve used for years to plug my motorhome into. Since I still have my motorhome and it’s parked in the RV garage I decided to hook up my 5er temporarily to my 30 amp 240 volt welder outlet. I had no idea that RV 30 amp cords were 120v only. Long story short, after connecting my 30 to 50 adapter I sent 240 volts down one leg of the buss bar. So everything on that side of the bus bar received 240 volts while the other side received zero. My question now is what will I need to replace? My refrigerator, GFCI, rooftop A/C were all on that side. The A/C seems to be working fine, but the fridge isn’t and the GFCI is smoked. Although I’ve wired up many homes, I certainly learned something about RV’a and their wiring today. I’m hoping just the circuit board on the fridge can be replaced. Anyone else have any experience with this? I’m sure this can’t be the first time this has happened. Stupid me!!

Happens all the time with DIY electricians and some real electricians when it comes to RV's because they do not read the information printed right on the plugs and receptacles.

1st, you adaptor should not have fit into a 30 amp 240 volt outlet. Seems that you have the wrong outlet and cord for your welder. The problem usually comes when a electrician or DIY wire 240 volts to a 120 volt RV receptacle. Which sounds like what you have done with your welder. I would start by fixing that first. A 120 volt 30 amp RV male plug cannot physically fit into a 30 amp 240 volt female outlet. You didn't run 240 down one leg but you did run 120 down the neutral leg.


Fridge, Furnace, Water Heater all have circuit boards that can be replaced. Fridge will have a glass fuse in back that may have blown and saved the fridge. Microwave also has an internal fuse.