Sorry it took so long... I forgot to take pics during my Aug trip.
I used a 120/240 50A even though my TT as most do, connects and runs from a 120V 30A. The reason is since most campgrounds use split phase transformers and one leg can become disconnected, I can test for this. (I've had this happen.) In other words the 30A receptacle may work but only one half of the 240V will. This is a problem since under a load the transformer can become unbalanced and the voltage can get dangerously low or high depending on the problem on the other leg. If you know there is a problem on one leg, I strongly advise again plugging into the other. Though this can be difficult to discern at parks that feature only 30A outlets.
Enough with the physics. I test prior to plugging my unit in. And I'll test after storms and if I think there's something wrong. As you can see I use the dog bone to test the 30A receptacle. I used a 50A replacement plug I found on clearance (reason #2 I made a 50A tester), a pair of banana plug to banana plug test leads that had a cut in the middle of the sheathing, and some heat shrink tubing.
I can use this tester to test an combinations of hots, neutral, and GND in 120/240 or 120/208 systems in parks.
2008 F150 FX4 5.4L & 3.73s
2014 PTM Tracer 3200BHT
Yes...I've finally made it to Prime Time!