Originally Posted by Summer2Go
My extension cord is 13 amp at home. Isn't that close enough?
The best thing to do is, if possible, not use an extension cord at all. The shorter the wire, the better. If you can, put the adapter directly on your 30A RV cord and plug it into the pedestal.
If you HAVE to use an extension cord....get a better one.
In your scenario, the pedestal will be 20A, your trailer will be 30A, and your wiring will be 13A. You never want your wiring to be the weak link. It'll possibly catch on fire before your breakers will trip. Adding 25-50 feet of cord makes that worse, as the smaller cord will warm up due to resistance.
Now, if all you were doing is running lights and such...not so much of a problem. Try to run your AC or microwave, etc. and you may very well put yourself at risk of a really bad time.