A safer 50-amp to 20-amp adapter
Just because you can buy something on eBay doesn't make it safe!
Don’t overload your extension cords with the wrong adapter
I’m not 100% comfortable using a 50-amp to 30-amp dogbone adapter to plug a 30-amp RV into a 50-amp pedestal outlet. Yes, I know there’s dozens of manufacturers who make them. And yes, the 50-amp outlet on a pedestal is often in much better shape than the worn out 30-amp outlet. But technically it’s a code violation since this is a 10-gauge shore power cord rated for 30-amps of current that’s plugged into a 50-amp circuit breaker.
However, the 30-amp main circuit breaker in your RV should be able to limit the current flow in the shore power cord to 30-amps and prevent overheating and a possible fire. So while it’s technically a code violation, it’s probably safe for your RV shore power cord.
Danger, Will Robinson…
But I’m seeing more people using a 50-amp to 15-amp adapter to power things like picnic tables full of slow cookers and electric griddles. And in this case, with a few adapters you can easily create conditions where small extension cords rated for less than 15 amperes can be connected to carry up to 50 amps. That’s a guaranteed meltdown and possible fire!
A safer solution!
A better and safer solution is a 50-amp adapter cord that includes a pair of 20-amp circuit breakers for the Edison outlets. That way if you accidentally overload it with an air fryer or electric griddle it will just trip the 20-amp circuit breaker, not start a fire. But you still need to use 12-gauge extension cords for your air fryer and griddle.
I found this adapter on Amazon HERE.
Let’s play (and stay) safe out there…. Mike
Along the same idea that Brian mentioned in his comment why is it no different than plugging in a 16 or 18 gauge extension cord into a 15 or 20 amp outlet. Or plugging in a light or small appliance or such that has an 18 gauge cord. In those examples I believe the thought process is that the connected load won't overload the cord and the ocp device protects the cord in case of a fault.
Thanks for giving a safe option. If I had a 50 amp rv, I would have one of these in my "tool" drawer