50 amp fiver - 30 amp service

http://www.americanrvcompany.com/Camco-55025-Power-Maximizer-50A-Camper-Trailer-RVHere it is. It does say it won't work with GFI breakers, now very often found on the 20 Amp outlets. Keeping in mind that an RV doesn't really use the 240 volt application from a 50 amp outlet, rather, it uses each "hot" as a 50 amp 120 Volt line separately. Using this gives one 50 amp side 30 amps, and the other 20 amps. I understand well the point of keeping usage low during these hookups. The point of the story is that, unrestrained, a load that is typical or "normal" in a 50 amp rig will overload a 30 amp outlet. Even more so, using this rig, anything significant on the other leg will trip the 20 amp side. However, this adapter DOES provide a total of 50 amps to a plug that expecting 2x50. In that case it's better than the above-described adapter that puts both sides together on a 30 alone. If you can find a non-GFI 20 amp.
Bottom line: If you have a 50 amp rig, use a 50 amp outlet whenever possible.