If you are talking about plugging your 30 Amp RV into a 50 Amp plug at an RV campground, then yes you can safely do it. All you need is a 30 Amp To 50 Amp Adaptor which has a 120 volt 50 Amp male end and a 120 volt 30 Amp female end. You just plug your 30 Amp RV cord into the female end of the adaptor and plug the male end into the campground's 50 amp service plug.
If you are talking about plugging your 30 amp RV into a 220 volt 50 amp Welder plug then no that will not work. Read the answer I gave to the question below to find out why.
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