50 amp plug for a 30 amp unit

[CHS]

I have a dedicated 50 amp RV receptacle in my garage where I keep my 30 amp unit. I use a 50 X 30 adapter to plug RV in.
My question is, is it necessary to change out the one breaker being used for the single leg feeding the RV since I'm using it for a 30 amp unit.

[Bob Nodine]

Originally Posted by CHS

I have a dedicated 50 amp RV receptacle in my garage where I keep my 30 amp unit. I use a 50 X 30 adapter to plug RV in.
My question is, is it necessary to change out the one breaker being used for the single leg feeding the RV since I'm using it for a 30 amp unit.

No, double pole breakers should be tied together so if one line exceeds the breaker rating it will trip and also take the other breaker with it thus opening both lines. In many two phase applications current travels between the two phases thru the load. An RV 50 amp application connects devices between a phase and ground so unless their is an open ground the current travels between the phase and ground (110VAC) thru the load.

[CHS]

Originally Posted by Bob Nodine

No, double pole breakers should be tied together so if one line exceeds the breaker rating it will trip and also take the other breaker with it thus opening both lines. In many two phase applications current travels between the two phases thru the load. An RV 50 amp application connects devices between a phase and ground so unless their is an open ground the current travels between the phase and ground (110VAC) thru the load.

First let me update my last post. I already have a double pole breaker (sorry for the confusion. My mistake.

So would it be advisable to change the breakers to be 30 amp (double pole)
I'm just concerned the 50 amp is too high, but then while in garage, it is only used to keep the refrigerator and/or the converter running. I guess the 30 amp main breaker and the 15 amp ones in the RV panel would cover those items.

[10scDust]

Originally Posted by CHS

First let me update my last post. I already have a double pole breaker (sorry for the confusion. My mistake.

So would it be advisable to change the breakers to be 30 amp (double pole)
I'm just concerned the 50 amp is too high, but then while in garage, it is only used to keep the refrigerator and/or the converter running. I guess the 30 amp main breaker and the 15 amp ones in the RV panel would cover those items.

My opinion here.

If you are only going to use the outlet for the RV from here on out. If it would comfort you better, make you more at ease. Then change out the outlet as needed, drop out the one leg not needed for 30A (disconnected & capped off at each end), and put in a 30A breaker. Save the components for if you want to switch back to the traditional 50 amp set up. The wire used for the 50A is no problem for the 30A it will be carrying. Going the other way, 30A to 50A is another story.

I believe Bob is saying it will be okay and work for you the way you are doing it, plus your own deduction of the RV breakers in line for the just in case.

When I made my RV parking spot, w/carport, I ran capability to upgrade to 50 amp from 30 (the extra leg there & breaker slot, inside the conduit, etc) so if I ever traded up to an RV that needs it.

[EA37TS]

Originally Posted by CHS

First let me update my last post. I already have a double pole breaker (sorry for the confusion. My mistake.

So would it be advisable to change the breakers to be 30 amp (double pole)
I'm just concerned the 50 amp is too high, but then while in garage, it is only used to keep the refrigerator and/or the converter running. I guess the 30 amp main breaker and the 15 amp ones in the RV panel would cover those items.

Keep the 50 amp as is and adapt down to 30. You can always adapt down to 30 with no problems at all. You can’t increase from 30 to 50 without major effort.

Been there, done that and it cost me to make the change.

[16ACE27]

Originally Posted by Bob Nodine

No, double pole breakers should be tied together so if one line exceeds the breaker rating it will trip and also take the other breaker with it thus opening both lines. In many two phase applications current travels between the two phases thru the load. An RV 50 amp application connects devices between a phase and ground so unless their is an open ground the current travels between the phase and ground (110VAC) thru the load.

Not quite: The multi-use 240v/120v outlet has current flow from a phase to NEUTRAL (not ground) in the 120 VAC application in the breaker box in the RV. No current should flow through ground unless there is a fault.

[Bob Nodine]

Originally Posted by 16ACE27

Not quite: The multi-use 240v/120v outlet has current flow from a phase to NEUTRAL (not ground) in the 120 VAC application in the breaker box in the RV. No current should flow through ground unless there is a fault.

Of course, that is what I meant. My poor choice of words and I do know the difference between ground and Neutral. In fact their are many kinds of grounds and one should never confuse Neutral with any type of ground. My bad. I have been working in the electronics and electrical field for over 55 years and at 77 still work on 3 phase variable frequency motor drives.

[Bob Nodine]

Originally Posted by CHS

First let me update my last post. I already have a double pole breaker (sorry for the confusion. My mistake.

So would it be advisable to change the breakers to be 30 amp (double pole)
I'm just concerned the 50 amp is too high, but then while in garage, it is only used to keep the refrigerator and/or the converter running. I guess the 30 amp main breaker and the 15 amp ones in the RV panel would cover those items.

As others have stated the downstream breakers in your RV will take care of protecting things. Your RV should have a 30 amp main breaker in the distribution box and 20 and 15 amp breakers downstream form that for individual outlets and appliances. The wire between that 30 amp breaker and the 50 amp RV outlet breaker in your garage is the only wire that is being fused at 50 amps. The main reason for the ampere rating is to protect against fire hazards due to overheating wire at steady state continuous current. It is not very likely that you will have a continuous current flow at 50 amps in the #10 wire that is rated for 30 amps because the 30 amp main breaker in your RV will trip before the wire has time to sufficiently heat to cause a fire.

In other words what you are doing is ok.

[CHS]

Originally Posted by Bob Nodine

As others have stated the downstream breakers in your RV will take care of protecting things. Your RV should have a 30 amp main breaker in the distribution box and 20 and 15 amp breakers downstream form that for individual outlets and appliances. The wire between that 30 amp breaker and the 50 amp RV outlet breaker in your garage is the only wire that is being fused at 50 amps. The main reason for the ampere rating is to protect against fire hazards due to overheating wire at steady state continuous current. It is not very likely that you will have a continuous current flow at 50 amps in the #10 wire that is rated for 30 amps because the 30 amp main breaker in your RV will trip before the wire has time to sufficiently heat to cause a fire.

In other words what you are doing is ok.

Thank you. Going to leave as is.