Originally Posted by NXR
The easy way but not free: https://www.homedepot.com/p/GE-RV-Pa...32SS/203393689
If I was just installing one, I'd do a 50 and use an adapter, which you may already have. That, in fact, is what I did although I needed 50. I figure if we buy a smaller RV it's an adapter.
That will require two side by side breaker slots and heavier wire, though.
When we had a 30 amp travel trailer, I installed a 30 amp RV box on the side of the garage (separate from the house). Then we decided to park the camper in a slightly different spot. So, I installed a second 30 amp RV box. Then we ended up with a 50 amp fifth wheel, and ended up removing the 2nd 30 amp box and installing one like pictured above from Home Depot, except ours came from Menards. I did have an electrician install it, as they used (I think) 6 gauge wire. But the nice thing is, we now have 50, 30, 20, and a second 30 amp box. Yes, it cost a pretty penny, but the joy of being able to use the camper at home all Summer and all Winter is worth every penny spent.
Here's a photo of the first 30 amp box and on the electric panel board, on the end, you can see the second 30 amp box before it was swapped out for the 50/30/20.
So, if I can give you any advise, let it be this... install, at least, a 50 amp box and use a step down dog bone for 30 amp and spare the expense of having to install again later when you switch over to a 50 amp RV. You'll be kicking yourself then, if you do only the 30 amp now.
Another reason why I went with this specific 50/30/20 amp box is because it had the breakers right in the box with the plug-ins. I looked at several 50 amp only boxes, and none had a breaker or a cut-off switch with the box.
You do know, when plugging in your camper, you should always flip the breaker first, then plug the camper in. When unplugging, you flip the breaker off first, then unplug. This keeps your plug on your camper from arching and getting pitted, and eventually wearing loose and become a fire hazard.
The 50/30/20 box above is wired into the panel on a dedicated line. Inside the panel, it's wired to a 70 amp breaker. The box itself has a 50, 30, and a 20 amp breaker. To reach the 70 amp breaker would require unscrewing the panel door every time I plugged in or unpluged the camper.
That is something you really should consider also. If you get the 30 amp box and it has no cut off switch or breaker in the box itself, you'll need to run to the main breaker panel where that box is wired to in order to flip the breaker on and off every time you plug in and unplug the camper. THIS IS SOMETHING YOU REALLY NEED TO CONSIDER. Where is the breaker? in the RV box, or on your garage or house electric breaker panel?